Pollination in Greenhouse Gardening [Hometown Structures]

By far the most common question I get about growing vegetables in my Hometown Structures greenhouse is “but how do the plants get pollinated?” And as with most things in gardening, the answer just isn’t that straightforward. Of course, it is an important consideration when planning what you will grow in your greenhouse garden! The truth is, I don’t rely on pollinators in my greenhouse the same way that I do in my outdoor vegetable garden, and there’s a few reasons for this - as well as a few techniques I use instead to ensure my flowering plants are being manually pollinated by hand so they can produce the harvests I want them to. While there’s certain limitations in pollinating a greenhouse garden, most of them are easily overcome, allowing you to grow a wide variety of fruits and vegetables in your greenhouse with very little extra time and attention.

The role of pollinators

Without getting too science-y on you, pollinators play a crucial role in a garden by transferring pollen from the male part (stamen) of a flower to the female part (pistil). This process is essential for the fertilization of plants and the production of seeds and fruits. Pollinators ensure that plants can reproduce and continue to exist. A diverse population of pollinators supports a wide variety of plant species in a garden. Many of the fruits and vegetables we eat rely on pollinators for their production, and pollinators contribute to the overall health and balance of the ecosystem in a garden. Common pollinators in gardens include bees, butterflies, moths, hummingbirds, and bats. But of course, these creatures can have a difficult time finding and entering your greenhouse!

How do bugs pollinate plants in the garden?

Bugs have a few clever tricks to spread pollen from one flower to another. As they buzz around, pollen sticks to their furry bodies. When they visit another flower, some of this pollen can rub off, fertilizing the plant. Some bugs have long tongues that they use to suck nectar from flowers. As they do this, pollen can get stuck to their tongues and be transferred to other flowers. Other insects can vibrate their bodies to shake pollen loose from flowers. This helps to ensure that the pollen is spread effectively to many different plants.

How does pollination affect yield and fruit production?

When a pollinator successfully transfers pollen to the female part of a flower, it can lead to fertilization. Fertilization results in the development of seeds, which are essential for the reproduction of plants. In many cases, the development of seeds triggers the growth and maturation of fruits. These fruits often contain nutrients and are attractive to animals (including us humans!), which can help disperse the seeds. Without pollination, many plants would be unable to reproduce, leading to reduced yields and fewer fruits.

In a greenhouse, it is often a closed environment which pollinators cannot enter. Even in a backyard greenhouse with open windows and doors throughout the season, it is less likely that you will see a large population of pollinators inside, simply because it is not an organic environment or as much a part of the local ecosystem. While companion planting pollinator friendly varieties may help, we need to consider this when choosing what to plant and pick varieties that have self pollination features, or can be hand pollinated.

Which vegetable plants need pollination?

Many vegetable plants require pollination to produce fruit. However, this does not mean they need pollinators in order to do it, since many are what is called self-pollinating. Some common examples include anything in the Cucurbits family which includes squash, zucchini, pumpkins, cucumbers, and melons as well as the Solanaceae family of plants which includes tomatoes, peppers, eggplants. Legumes such as beans and peas and many fruits such as apples, berries, cherries, and peaches also require pollination.

How does biodiversity affect pollination?

A diverse ecosystem with a variety of plant species and pollinators can lead to more efficient and effective pollination. Some pollinators have evolved to specialize on particular plant species. A diverse ecosystem can support a wider range of specialized relationships, ensuring that more plants are pollinated. When multiple pollinators are available, they can visit more flowers, increasing the chances of successful pollination. It really is a numbers game! A diverse ecosystem is more resilient to disturbances, such as habitat loss or climate change, which can affect pollination rates. A diverse ecosystem can also support genetic diversity among plants, which can make them more resistant to pests and diseases.

What is self pollination?

Self-pollination occurs when pollen from a plant's own stamen (male part) is transferred to its own pistil (female part). This can happen in the same flower or between different flowers on the same plant. While self-pollination can ensure that a plant reproduces, it can also lead to inbreeding depression. This is when offspring inherit harmful genetic traits from both parents. To avoid inbreeding depression, many plants have evolved mechanisms to prevent self-pollination, such as having separate male and female flowers or releasing pollen at different times. However, self-pollination can be beneficial in certain situations, such as when pollinators are scarce or when a plant is isolated such as in a greenhouse.

What plants are capable of self pollination?

Many vegetable plants can self pollinate, making them a good choice for a greenhouse garden. Some examples include:

Tomatoes: While they can also be cross-pollinated by bees, tomatoes are primarily self-pollinating.

Peppers: Similar to tomatoes, peppers can self-pollinate, but cross-pollination can often lead to higher yields.

Eggplants: Eggplants are also self-pollinating plants.

Squash: Many varieties of squash, such as zucchini and yellow squash, are self-pollinating.

Cucumbers: While cucumbers are typically cross-pollinated, some varieties can self-pollinate.

Beans: Beans are self-pollinating plants.

Peas: Peas are also self-pollinating.

What is cross pollination?

Cross pollination occurs when pollen from one plant is transferred to the pistil of another different plant. Insects, birds, bats, and other animals can transport pollen from one plant to another as they gather nectar or pollen for food. Wind can carry pollen from one plant to another, especially in plants with small, lightweight pollen grains. In aquatic plants, pollen can be carried by water currents. Cross-pollination can lead to genetic diversity among offspring, as they inherit traits from both parents. This can make them more resistant to pests, diseases, and environmental changes.

How can you pollinate plants by hand in a greenhouse?

Pollinate greenhouse plants with hand pollination:

First differentiate between male and female flowers based on their structures. Male flowers typically have stamens (pollen-producing organs), while female flowers have pistils (ovary-containing organs). Gently touch the stamen of a male flower to the pistil of a female flower. This will transfer pollen grains, potentially leading to fertilization. Perform this process for multiple flowers to increase the chances of successful pollination.

Pollinate greenhouse plants with fans:

Place fans within the greenhouse to circulate air and disperse pollen. This can help simulate natural wind and increase the likelihood of pollen reaching different plants. Experiment with different fan speeds and placement to find the optimal conditions for pollen dispersal.

Pollinate greenhouse plants by shaking plants:

Gently shake or tap plants to dislodge pollen and facilitate its movement. This technique can be particularly effective for plants with dangling or pendulous flowers.

Pollinate greenhouse plants using a small paintbrush:

Gently brush a small paintbrush against the stamens of male flowers to collect pollen. Apply the pollen-laden paintbrush to the pistils of female flowers.

Timing pollination correctly successful fruit production.

Look for flowers that have fully opened and are displaying their reproductive organs. Some plants exhibit color changes in their flowers when they are ready for pollination. For example, tomato flowers often turn yellow.

Ensure that the plant is healthy and growing vigorously. A stressed or unhealthy plant may not be receptive to pollination. Provide the plant with sufficient nutrients to support flowering and fruiting.

Many plants have optimal temperature ranges for pollination. Research the specific requirements of your plant species. High humidity can promote fungal growth and interfere with pollination. Maintain adequate ventilation in your greenhouse or garden.

If you are relying on pollinators, monitor their activity around your plants. When you see them visiting flowers, it's a good sign that the plants are ready for pollination.

If you're unsure, try pollinating a few flowers at different stages of development to see what works best.

Looking for a high quality pre-made greenhouse in Massachusetts? Hometown Structures offers the finest craftsmanship with custom designs in a wide variety of sizes perfect for the home gardener to give your plants the perfect climate to thrive in a protected environment, keep pests away from your plants, grow plants and food that don’t otherwise exist in your area/climate and extend your season with options including 8mm twin wall polycarbonate for optimal insulation, venting and windows. Every custom shed greenhouse comes with 50-Year LP Siding and 30-Year Collapse From Snow Warranty.

Tap here to visit their website to learn more and book a design consultation today.

How To Control Greenhouse Temperature [Hometown Structures]

Why is temperature control in greenhouse gardening important?

Plants are fussy - and while we can do everything in our power to work with nature and not against it by planting things in season that love the heat or cold, there will always be times in owning a greenhouse where you want to control the temperature. Thankfully when I designed my greenhouse with Hometown Structures we were able to implement a lot of features that help to keep things cool in the summer and warm in the winter, but since different plants have specific temperature requirements for germination, growth, flowering, and fruiting, maintaining these conditions with every available tool is important to ensure healthy development. 

Extreme temperatures can cause stress, leading to stunted growth, reduced yield, and susceptibility to diseases and pests - while on the opposite end of things consistent temperature management results in better flavor, color, and nutritional value in crops. Which means happier plants and more food in your harvest basket.

If you’re growing food in a greenhouse with a focus on keeping things low maintenance, then it’s even more important to get your temperature under control, since many diseases and pests thrive in extreme temperature conditions which cause plant stress. Maintaining optimal temperatures can help prevent disease outbreaks and precise temperature control allows for efficient use of heating and cooling systems, reducing energy consumption and costs.

What are the challenges of excess heat in a greenhouse?

High temperatures can be harmful to many plants because extreme heat causes plants to lose water faster, making them wilt and dry out. This can slow down or stop the process that plants use to turn sunlight into food, which affects their growth. Hot weather also makes it harder for plants to get nutrients from the soil, which can weaken them, can cause flowers and fruits to fall off before they're ripe, and can burn plant leaves. These conditions also encourage pests and diseases to thrive. Not to mention, to cool down plants, air conditioning systems need to work harder, which increases energy costs.

What are the challenges of excess cold in a greenhouse?

Cold temperatures can als be a big problem in a greenhouse. When it's cold, plants may grow much slower, and very cold temperatures can damage or even kill plants. Cold weather also delays the start of flowering and fruit production. Cold air holds less water, which can lead to plant diseases, and to keep plants warm, you need to use a lot of energy, which can cost a lot of money unless you use natural, energy efficient techniques.

Natural greenhouse Ventilation Techniques

Natural ventilation helps keep greenhouses healthy by letting fresh air in and old air out. But it can also help you regulate the temperature of your greenhouse. Two main parts of a greenhouse that help with this are vents on the top and sides, called ridge vents, and special side panel vents called louvered side panels. You can also strategically place doors and windows to take advantage of cross breezes.

Ridge vents are located at the very top of the greenhouse roof, while side vents are on the walls. How these vents are placed is important for good airflow. Since hot air rises, the top vents should be positioned to pull hot air out like a chimney. The side vents should be on the side where the wind usually comes from to let cool air in. Together, these vents create a draft that helps to keep the greenhouse air fresh.

Side panels with louvers have adjustable slats that let you control how much air comes into the greenhouse. By changing the angle of the slats, you can decide how much air to let in based on the weather and what your plants need. This helps you keep the greenhouse at the perfect temperature and humidity level.

Manual and automated ventilation options:

Manual ventilation involves opening and closing vents by hand based on weather conditions. While labor-intensive, it provides precise control. You can also use automated ventilation, which has sensors that monitor temperature and humidity levels, triggering the automatic opening and closing of vents. This method offers convenience and energy efficiency.

Shade Cloth To Keep Things Cool

Shade cloth is a mesh-like material that reduces solar radiation entering the greenhouse. It comes in different percentages that define how thick the material is and how much light can still get through.  The ideal shading percentage depends on several factors - different plants have varying light requirements, and solar intensity varies by region.Light levels also change throughout the year. But generally, shade cloth percentages range from 30% to 90% with 30-40% being the most common.

During peak summer months, higher shading percentages may be necessary to prevent overheating. As daylight hours shorten and solar intensity decreases in the fall and winter, shade cloth can be removed or replaced with a lower percentage.

Exterior sunscreens are installed on the outside of the greenhouse to reflect solar heat before it enters. These can be painted on and typically wash off over the course of a year or so naturally. Some are also made of reflective materials like aluminum or acrylic coatings that deflect a portion of the sun's rays, preventing them from entering the greenhouse and contributing to heat buildup. Reflective sunscreens can also help protect plants from intense UV radiation.

Evaporative Cooling Systems

Evaporative cooling is a common method to reduce greenhouse temperatures, particularly in dry climates. It works by taking advantage of the cooling effect of water evaporation. Wet wall or pad systems are a popular choice for evaporative cooling in greenhouses. These systems involve a porous material, often made of cellulose or synthetic fibers, that is saturated with water. As hot air is drawn through the wet pad, the water evaporates, absorbing heat from the air and cooling it down. This cooled air is then circulated through the greenhouse.

Installation typically involves mounting the wet pads on one or more sides of the greenhouse. A water distribution system is required to keep the pads constantly wet.   

Proper maintenance includes regular cleaning of the pads to prevent clogging and ensuring adequate water supply. It's essential to monitor water quality to prevent mineral buildup and damage to the pads.

Misting and fogging systems spray tiny drops of water into the greenhouse. This helps cool specific plants or areas by making the air around them humid. It can also help some plants by adding moisture to the air. But too much mist can cause plant diseases, so it's important to be careful.

Evaporative cooling systems can make greenhouses cooler, but how well they work depends on things like how humid it is, how hot the air is, and how much air is moving around. It's important to think about these things when setting up and using an evaporative cooling system.

Greenhouse Temperature Management Through Watering

Water can help cool down a greenhouse in addition to keeping plants hydrated. Using cold water to water your plants can slightly cool the soil and plants, which can help the whole greenhouse feel cooler. However, this cooling effect is small and works best when used with other cooling methods.

Drip irrigation delivers water directly to the root zone, minimizing water loss through evaporation. This reduces soil moisture levels, which can help lower soil temperature and subsequently, air temperature. Soil moisture sensors can be used to optimize watering, preventing excessive moisture that can lead to increased humidity and potential disease issues.

Wetting pathways and floors can be effective in small greenhouses or during short periods of extreme heat. However, excessive moisture can create a humid environment, which is not ideal for all plants and can promote disease development. It's crucial to balance the benefits of cooling through watering with potential drawbacks like increased humidity and disease risks. These techniques should be used in conjunction with other cooling methods for optimal temperature management.

Heating a greenhouse

Thermal mass and heat storage are effective strategies for harnessing solar energy to heat a greenhouse. By capturing and releasing heat strategically, these methods can significantly reduce reliance on traditional heating systems. You can use things like water, rocks, or bricks to store heat from the sun in your greenhouse. This helps keep it warm without using a lot of heat from other sources. These materials soak up the sun’s heat during the day and slowly release it at night.

As the greenhouse cools down at night, the thermal mass materials gradually release stored heat, warming the surrounding air. This helps to maintain a more stable temperature throughout the night.

Underground Cooling Pipes

While primarily used for cooling, underground pipes can also contribute to heat storage. During the day, excess heat can be transferred to underground pipes filled with water. The earth acts as a heat sink, storing the heat. At night, the warmer water can be circulated back into the greenhouse to provide supplementary heat.

Insulating a greenhouse

Insulation is crucial for maintaining a stable temperature within a greenhouse, especially during colder months. Insulation acts as a barrier, preventing heat from escaping the greenhouse. This helps to maintain a warmer interior even when outside temperatures drop. By reducing heat loss, insulation helps to lower heating costs. Insulation contributes to a more stable internal temperature, reducing fluctuations that can stress plants. A well-insulated greenhouse can better withstand sudden drops in temperature.

Common insulation materials for greenhouses include:

• Bubble wrap: Offers a cost-effective and lightweight solution.   

• Insulation blankets: Provide excellent insulation and can be easily removed when not needed.

• Reflective insulation: Helps to reduce heat loss and reflect sunlight.   

• Foam board insulation: Offers high R-value for superior insulation.

The choice of building materials significantly influences a greenhouse's ability to retain heat. Glass offers excellent light transmission but poor insulation. Double glazing can improve insulation. Polycarbonate provides good light transmission and insulation, especially twin-wall polycarbonate. Acrylic offers a balance of light transmission and insulation, but can be more prone to scratching.

For the greenhouse frame, metal conducts heat efficiently, so insulation is crucial to prevent heat loss. Wood provides better insulation than metal but requires proper sealing to prevent heat loss. 

For the greenhouse foundation, concrete has high thermal mass, storing heat during the day and releasing it slowly at night. Wood offers some insulation but may require additional measures for colder climates.

Gaps and cracks in the greenhouse structure can lead to significant heat loss. Proper sealing is essential.

Energy efficiency in greenhouse temperature control is crucial for several reasons. Efficient systems consume less electricity or fuel, leading to significant savings on energy bills. Energy-efficient systems often rely on renewable resources or consume less energy, reducing greenhouse gas emissions. Promoting environmentally friendly practices is essential for long-term sustainability. Energy-efficient greenhouses are better equipped to handle climate variations and extreme weather events.

Looking for a high quality pre-made greenhouse in Massachusetts? Hometown Structures offers the finest craftsmanship with custom designs in a wide variety of sizes perfect for the home gardener to give your plants the perfect climate to thrive in a protected environment, keep pests away from your plants, grow plants and food that don’t otherwise exist in your area/climate and extend your season with options including 8mm twin wall polycarbonate for optimal insulation, venting and windows. Every custom shed greenhouse comes with 50-Year LP Siding and 30-Year Collapse From Snow Warranty.

Tap here to visit their website to learn more and book a design consultation today.

What To Grow In a Greenhouse [Hometown Structures]

Benefits of growing food in a greenhouse

Greenhouses protect plants from cold weather, allowing you to grow crops earlier in the spring and later into the fall. You can even cultivate plants year-round in some cases. Since you can regulate temperature, humidity, and light levels, greenhouses are ideal for creating optimal growing conditions for specific plants. The enclosed nature of a greenhouse helps to shield plants from pests like insects and rodents, and also minimizes the spread of diseases that can be carried by wind or rain. Because of the ability to control the environment, you can grow a wider range of plants in a greenhouse than you could outdoors in your local climate. This includes exotic fruits, vegetables, and flowers that wouldn't normally survive in your area. Greenhouses safeguard plants from harsh weather conditions like hail, strong winds, and excessive sun exposure. This can result in healthier plants and higher yields.

Choosing the right plants for your greenhouse is absolutely crucial for its success. It's like having the perfect kitchen but picking ingredients that don't go together - you might end up with wasted time, effort, and resources. Different plants have specific requirements for temperature, light, humidity, and spacing. Matching these needs with your greenhouse's capabilities ensures the plants thrive. Imagine putting a cactus in a constantly damp environment - it wouldn't do well! Choosing plants suited to your greenhouse minimizes the extra effort required to maintain ideal conditions. You won't be constantly battling unsuitable temperatures or humidity levels for your plants. Selecting high-yielding plants for your specific greenhouse environment allows you to harvest the most vegetables, fruits, or flowers possible from your space. Plants under stress from unsuitable conditions are more susceptible to pests and diseases. Picking the right plants helps them stay healthy and fight off potential problems. By carefully considering your greenhouse's environment and choosing compatible plants, you set the stage for a thriving and productive greenhouse experience. But before you pick your plants, you need to know what climate you’re working with - and that’s where garden zones come in.

What are garden zones?

Garden zones, also known as plant hardiness zones, are specifically designed for gardeners to identify which plants are most likely to thrive in their local climate. Unlike climate zones, which are large geographic regions with distinct weather patterns, garden zones focus on a single factor: a region's average annual minimum winter temperature.

The most widely used system for garden zones is the USDA Plant Hardiness Zone Map, developed by the United States Department of Agriculture (USDA) Agricultural Research Service. This map divides North America into 13 zones, with Zone 1 being the coldest (average minimum temperature of -60 to -50°F) and Zone 13 being the warmest (average minimum temperature of 60 to 70°F). Within each zone, there are further subdivisions designated by the letters a and b. For example, Zone 7a has a slightly warmer average minimum temperature range (0 to 5°F) than Zone 7b (5 to 10°F).

By knowing your garden zone, you can choose plants that are more likely to survive and thrive in your local climate. This can save you time, money, and frustration in the long run. You can find your USDA Plant Hardiness Zone by entering your zip code on the USDA website https://planthardiness.ars.usda.gov/ or using a gardening app.

The best way to grow food in a greenhouse year round is by working with nature, not against it. Which means choosing heat loving, warm season crops in the summer and cold loving winter crops in the winter. Here’s a few of my favorites to get you started:

Warm-Season Food to grow in a Greenhouse

Tomatoes

There are many varieties of tomatoes that are well-suited for greenhouse cultivation. Determinate tomatoes ripen all at the same time so you can make all your sauces and salsas at once for preserving. They grow on compact bushes, so you probably don't need to stake these plants. Indeterminate varieties grow and produce fruit all season; therefore, you could use these tomatoes more regularly in salads and sandwiches. In between these two types are the semideterminate. As you might guess, they do both—produce a main crop that ripens at once, but also continue to produce up until frost. The really big, juicy tomatoes are probably slicer tomatoes, meaning they are thick and sturdy for slicing.

Some tomato varieties require pollination by bees or other insects. If you are not planning to introduce pollinators to your greenhouse, you will need to choose a self-pollinating variety. Many tomato varieties are now available that are resistant to common diseases such as fusarium wilt and verticillium wilt. Choosing disease-resistant varieties can help to reduce the need for pesticides in your greenhouse. Consider how long you want your tomatoes to take to mature. If you are growing in a cold climate, you may want to choose a variety that matures early.

Sun Gold Pole Cherry Tomatoes (Indeterminate)

Rare in grocery stores, 'Sun Gold's' plump, tangerine-colored fruits are a special treat at the peak of flavor in the garden-very sweet and juicy! Provide support for vigorous vines that easily reach 6' long. Pick a bit early and ripen indoors at room temperature. Low-acidity tomato. Disease resistant.

Green Zebra Pole Tomatoes (Indeterminate)

'Green Zebra' has excellent flavor and unique color—golden green with forest green stripes, developing a slight amber blush when ripe. The 2"–3" tomatoes have very smooth skin essentially free of cracks. Provide support for vines that reach 6' or more. More heat and drought tolerant than other varieties.

Brandywine Pole Tomatoes (Indeterminate)

Brandywines have been favored by tomato lovers for more than 100 years. Fruits often weigh around a pound but can weigh close to 2 pounds! 'Yellow Brandywine' turns golden yellow when ripe, with a balance of sweet and tart; 'Red Brandywine' has a rich, well-balanced tomato flavor.

Italian Roma Bush Tomatoes (Determinate)

An absolutely excellent heirloom tomato—firm, meaty, 3" oblong fruits with few seeds, on compact vines that are very productive. As a determinate type, most of the fruits ripen at the same time, which makes this tomato a good choice for canning. In areas with a long growing season, a second planting will double your harvest!

Cream Sausage Bush Tomatoes (Determinate)

True to name, these cylindrical, cream to pale yellow tomatoes are best harvested at 3"—when they start to look like little sausages! With a smooth, buttery, rich flavor, 'Cream Sausage' is ready to eat like an apple right off the vine, or save it for the kitchen to simmer into a yellow pasta sauce, create contrast in salsas, or slice up for a fresh salad. This highly productive cultivar is compact and perfect for containers.

Red Pride Bush Tomatoes (Determinate)

The blue ribbon winner! 'Red Pride' yields a bountiful harvest on vigorous, compact plants. Its reliable production of 10-ounce fruits combined with an excellent disease resistance package, including Alternaria stem canker, gray leaf spot, Fusarium wilt (1, 2), and Verticillium wilt, make it a winner for any garden!

Peppers

There are many pepper varieties that are well-suited for greenhouse cultivation, depending on several factors including your desired fruit size, flavor profile (sweet or hot), and plant growth habit (bush or vining).

Bell peppers are the most common type of pepper grown in greenhouses. They come in a variety of colors (green, yellow, orange, red, purple, and chocolate brown) and sizes, and have a mild, sweet flavor. Peppers are usually indeterminate plants, meaning they continue to produce new fruit throughout the growing season. Hot peppers come in a wide variety of shapes, sizes, and heat levels.

Shishito Chili Peppers

The 'Shishito' is finding its way into many restaurants as a popular appetizer. The 2"–4" slender peppers have a citrusy, slightly smoky flavor enhanced by grilling or sautéing, and can be the life of the party when an occasional hot one passes the mouth of the unsuspecting. Highly productive plants. 50–200 Scoville heat units (mild).

California Sweet Bell Pepper

An old-time favorite since 1928 for good reason! 'California Wonder's' large, uniform shape makes it ideal for stuffing. Delicious grilled, they are perfect for shish kabobs. Peppers left on the plant will turn a beautiful, bright red, and have more vitamin C than an orange! Good container variety, and dependable performer even in short season climates.

Habanero Chili Peppers

Prized by chile aficionados not only for its intense heat, but its distinct fruitiness, the habanero is used in sensational salsas and will turn a bland barbeque into a fiery feast! Habaneros are said to be 100 times hotter than jalapeños. 100,000-350,000 Scoville heat units (extremely hot).

Early Jalapeno Chili Peppers

Lots of bold flavor in a small, 3" pepper, 'Early Jalapeño' is better adapted to cooler climates than other jalapeños. Incredibly versatile, they're hot enough to add a little kick to your favorite dish, but mild enough for any meal. Enjoy green or allow to ripen to red for a sweeter, bolder flavor. Jalapeños rate 2,500–5,000 Scoville heat units (medium hot).

Most pepper varieties are self-pollinating, but some may benefit from hand pollination. Many pepper varieties are now available that are resistant to common diseases such as bacterial spot and powdery mildew. Choosing disease-resistant varieties can help to reduce the need for pesticides in your greenhouse. Consider how long you want your peppers to take to mature. If you are growing in a cold climate, you may want to choose a variety that matures early.

Eggplant

Eggplant is a great choice for greenhouse cultivation because it thrives in warm, controlled environments, and hates wind. Eggplant comes in many colors from dark purple to white and variegated stripes and shapes including round, elongated and large or small fruit. Earlier varieties are a good choice for colder climates.

Black Beauty Eggplant

A beautiful vegetable with lovely, lavender blossoms pretty enough to grow in the flower garden. 'Black Beauty' has set the standard since 1902 for large, high-quality fruit. Outstanding when harvested at their peak, the skin is tender, so no need to peel it. A widely used international food; there are countless recipes from Italy to China to Russia and beyond.

Long Purple Eggplant

This long, slender variety, not usually found in grocery stores, is flavorsome in countless recipes from Italy to China to Russia and beyond. Also called 'Italian Long Purple', this prolific heirloom will bring beautiful color to the garden and savory goodness to the table.

Jewel Amethyst Eggplant

‘Jewel Amethyst' is perfect for containers, with a tidy habit that makes harvesting a breeze. Glossy, oval, purple fruits are best harvested when about 3''–4 ½" long. Harvest regularly from this prolific plant and keep eggplant on the table throughout the season. Its firm texture and mild flavor make this mini eggplant ideal for roasting, frying, or glazing with a flavorful sauce.

Rattlesnake beans

Rattlesnake beans, like most beans, thrive in warm weather. But most beans stop producing when temps go above 90°F - rattlesnake beans don’t! They actually love the hotter temps, and a greenhouse provides a controlled environment where you can maintain the ideal temperatures (around 80-90°F) for them to flourish, especially if you live in a climate with cooler summers.

These beans are known for their extended harvest period. Greenhouses can extend the growing season for rattlesnake beans, allowing you to enjoy fresh beans for a longer time. Rattlesnake bean plants are vigorous growers and produce a high yield of beans. In a greenhouse, you can create optimal growing conditions that can maximize your harvest. Rattlesnake beans are vining plants, so they grow vertically and take up minimal floor space. This is a great advantage in a greenhouse, where space can be limited. You can easily train them to grow up a trellis or other support structure.

As mentioned earlier, rattlesnake beans are vining plants and will need some support to grow vertically. You can install a trellis, netting, or stakes in your greenhouse to support the vines. Rattlesnake beans are self-pollinating, so you won't need to worry about attracting pollinators to your greenhouse. Rattlesnake beans need consistent moisture, but avoid overwatering. Allow the soil to dry slightly between waterings. You can harvest rattlesnake beans when the pods are young and tender, or you can let them mature and dry the beans for shelling.

Malabar Spinach

Malabar spinach is a tropical vine that flourishes in hot and humid conditions. Greenhouses provide excellent control over temperature and humidity, allowing you to mimic its ideal growing environment year-round, especially in cooler climates. This vigorous vine can grow up to 10 feet in a single season. A greenhouse offers ample vertical space for it to sprawl and climb, unlike outdoor settings where it might be restricted. Malabar spinach produces leaves continuously throughout the growing season. Greenhouses can extend this period significantly, giving you a longer window to enjoy fresh harvests. Since it's sensitive to frost, greenhouses offer protection from chilly outdoor temperatures that can damage or kill the plant.

Provide a trellis, netting, or poles for the vines to climb. This encourages vertical growth and maximizes space usage. Malabar spinach prefers full sun to partial shade. If your greenhouse has limited natural light, you might need to supplement with artificial lights. Maintain consistent moisture in the soil but avoid waterlogging. The humid greenhouse environment might require adjustments in watering frequency compared to outdoors.

Cool-Season Crops

Lettuce

Lettuce prefers cooler temperatures. Most lettuce varieties mature quickly, within 30-70 days, meaning you can enjoy multiple harvests throughout a single greenhouse season. Lettuce plants are relatively compact, making them ideal for maximizing space utilization in a greenhouse. You can grow them in rows, beds, or even containers. There are many varieties of lettuce available, from crisphead to romaine to leafy greens, allowing you to cultivate a diverse selection in your greenhouse.

Buttercrunch Butterhead Lettuce

‘Buttercrunch' is a vigorous grower with a creamy yellow interior, buttery flavor and melt-in-your-mouth texture, pleasing palates since 1963. Small heads are perfect for a single-serve salad. The compact size makes it a good container variety, and it's also attractive in the flower-garden border.

Red Sails Leaf Lettuce

A favorite to use as baby greens, 'Red Sails' is ready to harvest after just 2 or 3 weeks and grows to a full head in just over 6 weeks. Very heat tolerant, the soft buttery leaves will grow well into warm weather without getting bitter. Contains more vitamins A and C than grocery-store lettuce! Attractive container variety, too.

Ice Queen Crisphead Lettuce

Ice Queen' dates back to 1883, and gets its name because it is cold tolerant, but also tolerates heat well and is slow to bolt. Also considered a summer crisp or Batavia, this bright, emerald green lettuce with frilly leaves has crisp texture and excellent fresh flavor. Also delicious as a baby green in as little as 21 days. You can harvest the outer, frilly leaves while waiting for the head to form.

Spinach

Spinach thrives in cooler temperatures, and most spinach varieties mature quickly, within 40-50 days from seeding. This rapid growth cycle allows you to have multiple harvests throughout a single greenhouse season. Spinach plants are relatively compact, making them good for maximizing space in your greenhouse. You can grow them in rows, beds, or even containers.

Bloomsdale Spinach

'Bloomsdale' is an early 1800's, dependable, open-pollinated variety. For growing tender, baby greens in as little as 28 days, you can sow seeds just 1" apart. Very nutritious—lots of vitamins A and C and iron. Grows great in a container too!

Kale

Kale is quite tolerant of a wider range of temperatures than some other cool-season crops. It can even handle frosts, adding to its resilience in a greenhouse setting. Most kale varieties mature within 50-70 days from seeding, allowing you to have multiple harvests throughout a single greenhouse season. Kale plants are not overly bushy, making them suitable for maximizing space utilization in your greenhouse. The three most common types of culinary kale include: curly (e.g., 'Redbor', 'Dwarf Blue Curled'), Russian (flat leaf with serrated edges, e.g., 'Red Russian'), and cavolo Nero (also called "dinosaur kale", the Italian lacinato type with dark, savoyed leaves, (e.g., 'Nero Toscana')

Redbor Kale

This kale has it all. Beautiful, ruffled leaves are tasty and have amazing color. Extremely cold tolerant, 'Redbor's' purple color and curliness intensifies, and flavor sweetens as temperatures drop in the fall; plants can last even through hard freezes. Sow with pansies, violas, and snapdragons for long-lasting fall color. Looks great in containers.

Red Russian Kale

Kale gets sweeter after the first fall frost. 'Red Russian', brought to North America in 1885, is sweet and tender all the time, making it excellent for mesclun, garnishes, and sautéing. The red veins, wavy margins, and foliage that resembles oak leaves make 'Red Russian' as attractive as it is delicious. Harvest baby greens in just 21 days.

Lacinato Kale

This tender kale is also known as black Tuscan kale, black cabbage, and black palm. Vigorous dark green to black leaves of this 18th century heirloom are favored by gourmets. Harvest the first shoots as tender young salad greens in just 21 days when 2"–4" tall, or achieve full-sized plants in 2 months.

Cabbage

The enclosed nature of a greenhouse helps shield cabbage plants from common outdoor pests like cabbage worms and aphids. It can also minimize the spread of diseases that can be carried by wind or rain. Consistent and cool temperatures in a greenhouse contribute to optimal head formation in cabbage. Fluctuating outdoor temperatures can sometimes hinder proper head development. Greenhouses safeguard cabbage from harsh weather conditions like hail, strong winds, and excessive sun exposure. This protection can result in healthier plants and potentially higher yields.

Red Acre Cabbage

Solid heads form early on small, compact plants making 'Red Acre' an ideal choice for small gardens. Resistant to splitting and cabbage yellows disease. Heads store exceptionally well in the refrigerator or root cellar.

One Kilo Slow Bolt Napa Cabbage

Also called napa cabbage, 'One Kilo Slow Bolt' has a delicate flavor, a soft texture in between that of lettuce and regular cabbage, and tight heads have a creamy yellow interior. Grows with ease in fall, and can be sown in spring if care is taken to protect young plants from temperatures of 50°F or below, which may cause plants to bolt. Grows best at 60°-65°F.

Carrots

Carrots can be grown in a greenhouse, but it requires more attention to detail compared to other vegetables. If you are a beginner greenhouse gardener, you might want to start with easier crops like lettuce or spinach before attempting carrots. However, with the right care and suitable varieties, you can enjoy fresh, homegrown carrots even outside the traditional growing season. Greenhouses protect carrots from cold weather, allowing you to plant them earlier in spring and harvest them later in fall, or even year-round in some climates. The enclosed nature of a greenhouse helps shield carrots from pests like carrot flies and root maggots, and minimizes the spread of diseases.

Carrots require loose, well-aerated soil to grow properly. Heavier, compacted soils can lead to deformed or stunted carrots. Amending your greenhouse soil with sand or other materials to improve drainage is crucial. Carrots need adequate sunlight for good root development. If your greenhouse has limited natural light, supplementing with artificial lights might be necessary. Carrots need proper spacing between them to allow for root growth. Overcrowding can result in stunted, misshapen carrots.

Choose carrot varieties suited for greenhouse cultivation. These varieties may be shorter or have slower bolting tendencies (going to seed) compared to outdoor varieties. Maintain consistent moisture in the soil, but avoid overwatering which can lead to root rot. The humidity levels in your greenhouse might require adjustments in watering frequency compared to outdoors. Carrots are cool-season vegetables, excessively high temperatures can negatively impact root growth.

Beets

Beets prefer cool weather. Most beet varieties mature within 50-60 days from seeding, meaning you can enjoy multiple harvests throughout a single greenhouse season. Beet greens are relatively compact, making them suitable for maximizing space utilization in your greenhouse. You can grow them in rows, beds, or even containers.You can harvest both the beet greens (tops) and the beetroot (bulb) for delicious and nutritious meals.

Touchstone Gold Beets

Not only does the color of this beet make it stand apart, but so does the flavor. Golden beets are known for being extra sweet and less "earthy" than their red counterparts. Best at 1"–3" round.

Scallions

Scallions prefer cooler temperatures. Most scallions mature quickly, within 40-60 days from planting. This rapid growth cycle allows you to have multiple harvests throughout a single greenhouse season, providing a steady supply of fresh scallions. Scallions are compact plants and don't require a lot of space. You can grow them in rows, beds, or even containers, making them ideal for maximizing space utilization in your greenhouse. You can harvest scallions at any stage of growth, using both the green stalks and white bulbs for adding flavor to various dishes. Scallions are generally quite resistant to pests and diseases, making them a low-maintenance crop to grow in a greenhouse.

White Lisbon Bunching Scallion

‘White Lisbon' is a green or spring onion, and sometimes referred to as a scallion or bunching onion. A popular variety since the 1700s because it produces dependably in widely varying conditions. It thrives in a wide range of soils, is heat and cold tolerant, and can be sown successively throughout the season. For the finest quality, pencil-thin onions, sow seed densely and do not thin seedlings.

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