Can You Grow Vegetables Year Round in a Greenhouse?

Gardeners know there is nothing like biting into a BLT made from tomato and lettuce from a garden. Produce tastes best when grown with one’s own hands, planted into the ground outside your window.

But for many throughout the nation, the outdoors is off-limits for months each year. The allure of freshly grown produce does not wane in the winter. A ripe tomato may become even more irresistible when snow and ice accumulate.

But can you grow tomatoes year-round in a greenhouse? Can you have a year-round greenhouse? Let’s explore.

Vegetables growing in a greenhouse

Gardeners Can Grow Vegetables Year-round in a Greenhouse

If you are ready to take on the financial investment, and labor of greenhouse gardening, you can feast on seasonal produce throughout the year wherever you live.

Let us look closer at:

  • Rotation planting for the highest greenhouse success
  • Growing vegetables out of season in your greenhouse
  • How much longer growing season you can expect from your greenhouse
  • Greenhouse tips for even the coldest climates

How to Grow Vegetables in a Greenhouse Year-round

Now that we know this is possible, there is a lot of research to do before you can start growing vegetables year-round.

When you’re attempting to cooperate with nature, there are a lot of conditions to consider and balance, including climate, sunlight, ventilation, pests, and more.

Find Your Growing Zone

With any gardening endeavor, it is paramount to analyze the growing zone where you live. Zones were established to provide a conservative estimate of the lowest prolonged freeze your home garden may need to endure. 

The United States Department of Agriculture established the USDA Plant Hardiness Zone Map to help horticulturalists plan their gardens. For example, a Zone 4a gardener should choose plants that can withstand a year-round low temperature of about 30 below. 

As someone who used to live in that zone, I can tell you this is accurate! However, these low temperatures are uncommon and not usually prolonged. Therefore, any permanent outdoor plantings should be selected for their ability to survive an occasional extreme cold snap.

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Freezing Temperatures

Often, these freeze temperatures are exaggerated to help gardeners with the “better safe than sorry” approach to choosing plants. In places with more temperate climates like Florida or Texas, the Zone map helps to determine permanent plantings like landscaping or large farms.

If you establish a greenhouse on your property, consider this building like other permanent outdoor plantings. While the vegetables are not sown directly into the ground, the outdoor conditions must be tracked to influence heat, humidity, and light levels within the greenhouse.

Once you have determined your growing zone, you will have an accurate depiction of the type of conditions you will also need to endure year-round.

Vegetables grown in a greenhouse year-round must be tended, even if the temperature is unpleasant outside!

Greenhouse with vegetables growing in a garden

Finalize Greenhouse Purpose

If the conditions around you make it prohibitive to have a greenhouse year-round, you can still get a lot of practical use out of a winter greenhouse.

Consider starting your seeds in a greenhouse setting to save money and jump-start your outdoor garden beds with mature plants.

Waiting for the last frost to recede can take forever, but your seedlings will be happy inside the warm, humid greenhouse.

Tomatoes and peppers receive a helpful head start in a greenhouse, where seeds have the precise conditions necessary to grow into strong plants.

While some plants take the seed-starting well, some are too delicate to survive a transplanting from greenhouse to garden bed.

Cucumbers, corn, peas, and all root vegetables, should be sown directly into the ground instead of a seed-starting process.

A greenhouse is also a great utility player on your property because it can offer a staggered harvest. Sow seedlings in batches with a few days or a week in between.

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This will help extend your harvest by offering a fully mature plant’s bounty as an older plant is starting to wind down.

Gather Supplies

There are countless free do-it-yourself greenhouse building plans online to help you with building your ideal outdoor growing space. Many times, you can repurpose materials you already have, like old windows, treated wood boards, and plastic sheeting.

While much of a greenhouse can be cobbled together, setting the interior conditions is a precise science. Greenhouses, especially ones used for year-round growing, must artificially establish the correct growing conditions inside the greenhouse. This is done using heaters and fans.

If you’ve ever entered a greenhouse, you know these are hot and humid environments. Establish an artificially tropical environment using oscillating fans to promote ventilation and encourage pollination and space heaters to maintain a consistent, high temperature.

These climate enhancements are the largest ongoing investment in your year-round greenhouse project. Especially in cool climates, maintaining a tropical environment can cost thousands each season.

If you are looking for ways to save money in the greenhouse, consider composting inside the greenhouse structure. Compost gives off considerable heat, which your plants will love.

This nutrient-rich soil is also perfect for providing the robust dirt plants need to grow to their potential.

Start Planting

Whether you decide to plant year-round in your greenhouse, it is always a good idea to follow a seasonal planting schedule. These planting schedules are not only recommended for the air temperature, but also for sunlight strength and other seasonal factors.

Efficient greenhouse plants to help you get started include many vegetables that thrive in cooler conditions. This way, you don’t have to fret about establishing a perfect tropical environment when just getting started with gardening this way. Look for these vegetables:

  • Brassicas (broccoli, cauliflower, Brussels sprouts)
  • Alliums (onions, garlic)
  • Greens (lettuce, spinach)
  • Root vegetables (beets, potatoes, carrots)
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Once you feel confident about your greenhouse, you can move to fussier vegetables. The next step is vegetables that thrive in summer conditions, like tomatoes, peppers, and green beans.

The only vegetables you should skip are the huge ones, like corn.

Greenhouse FAQ

Can you grow out of season in a greenhouse?

Yes! Gardeners can grow out of season and many do. Elaborate heating, ventilation, pest control, and lighting systems will be needed to promote healthy plants. 

How long does a greenhouse extend the growing season?

Depending on where you live and the amount of investment you want to make, you can extend your growing season year-round.

Can you have a year-round greenhouse?

Yes. Year-round greenhouses are possible for most people, no matter where they live. Depending on your climate, extensive ventilation, heating, and lighting may be needed.

Can you grow vegetables in a greenhouse in the summer?

Yes. If you have the proper growing environment established within your greenhouse, you can grow vegetables in a greenhouse during summer. Do your research to understand the humidity, lighting, and heat conditions needed for success.

Can you grow tomatoes year-round in a greenhouse?

Yes. Tomatoes can be grown year-round in a greenhouse. However, these are one of the most finicky plants to grow this way. Often called “hot-house plants” tomatoes need a considerable warm environment to thrive.

Can you grow vegetables in the winter in a greenhouse?

Yes. Depending on where you live, you can have success growing vegetables in the winter in a greenhouse without much effort. However, cold climates must be able to regulate ventilation, heat, and light sources to nurture plants.