I am always leery of any list that starts off with the word “best.” The reason being is that “best” is a subjective term that may or may not apply to the unique situation that we each face. As such, the word “best” in this blog is applied based on circumstance.
In this article, we’ll cover what greenhouses are good for, common problems, and what are the best vegetables to grow in a greenhouse. Let’s get started.
The Role of a Greenhouse
A greenhouse is a tool. How you use that tool determines what kinds of foods will grow the best inside of it. Many of us use our greenhouse to:
- Start seeds before the last frost-free day
- Grow and develop seedlings until they are ready to harvest
- Shelter fragile plants that need a specialized environment
- Extend harvest of plants that would either not survive the turn of the season from summer to autumn or from autumn to winter
What your growing goals are is the first hurdle we come to when determining which types of plants are best for your greenhouse.
Growing Goals and Growing Obstacles
In my house, the garden’s growing goals are all about food production, and those range from starting seeds to extending harvests. I practice successive planting which is a little gardening trick many gardeners use to get the most production out of a plot of land.
It works by making sure that there is a viable crop ready to go into the ground as soon as you harvest whatever is growing. Successive gardening is a practice that cuts down on the days needed before a harvest and makes a perfect example of how I use my greenhouse.
So, time is one obstacle others usually include:
- Your location
- Seasonal variations -temperatures, etc.
- Growing season length
- Plant sensitivity
- Gardening space
What are the growing obstacles that you face throughout your growing season?
Late Last Frost-Free Day
Greenhouses are perfect for starting your seeds indoors before it is safe to plant seedlings outdoors. Doing so gives you a jump start on the growing season. However, you must harden off the plants so that the transfer in temperature does not kill them.
The best plants to grow in a greenhouse are those plants that take the longest to reach harvest. For example, tomatoes work better than do lettuce or radishes. The latter are both very fast crops, though you could plant all three.
Tomatoes work better because they take much longer to produce a harvest. You can get a jump start on the growing season; the following plants are the best to grow in a greenhouse if you want to shorten your harvest times.
Vegetables to Start in a Greenhouse
If you want to get ahead of the seasons and start your crops early, these are the best vegetables to do so:
- Collard Greens
Certain crops work better in a cold frame rather than a greenhouse, and those include:
- Salad greens such as lettuces
- Carrots, which do not transplant well
- Herbs that like cool weather
If you are planning to grow the entire crop in the greenhouse, then these plants work too. Plants that are wind-pollinated, such as corn might not produce much though. If you are building a greenhouse vegetable garden, then be sure to consider the challenges of pollinating when you choose a greenhouse design.
A greenhouse is a perfect tool for successive planting. As such, you can use your greenhouse to start seeds 4-8 weeks before you want to plant. Here, in zone 8A, we start tomatoes in mid-March so that they are healthy seedlings about a foot tall. They go from the seed trays where they spout to four-inch containers.
With heirloom tomatoes, we start the seeds eight weeks before the anticipated planting date, and they make it all the way to one-gallon pots before we transplant them into the ground in mid-May or early June.
When you apply successive gardening, you anticipate the harvest date for plants and then plan for your next crop while the current crop is still growing and maturing. The goal is to utilize the smaller growing space of a pot to start your next crop.
What you are doing is growing two gardens at once, but because the next set of plants are small, they require less room. What you gain is about a 6-8-week reduction in time between one harvest and the next.
So, a greenhouse is a tool that helps you increase the total harvest or yield throughout your growing season. As such, most plants that you would grow in your garden are the “best” plants to grow in a greenhouse if your goal is successive gardening. The exceptions are those plants that do not transplant well, such as carrots.
Growing Crops in Cold Climates
In many areas around the world and the US, the growing season is either short, and the winter is very harsh. For both of those situations, growing vegetables in a greenhouse is the perfect workaround.
However, not every type of plant grows well in a greenhouse during every season of the year. Some plants need more direct light than do others, but you can offset those lighting needs by using grow lights to extend the season on your greenhouse vegetable garden.
Grow lights were first used by the aquarium industry to grow corals and plants for home aquariums. Because of changes to the legal status of marijuana, grow lights are now available almost everywhere and at more affordable prices.
What this means is that even for places where the growing season is short, you can offset the drop in sunlight by using artificial light.
Colder growing climates are also affected by shorter days and less light. For many plants, it isn’t just the drop in the light that causes problems, but the drop in temperature. For those reasons, a greenhouse becomes a tool to offset both the reduction in lighting and the reduction in warmth.
In both cases, the best plants to grow in a greenhouse are those that need additional light and a warmer growing climate. Those can range from citrus trees in pots, to vegetables that you want to grow year-round.
For year-round growing, you want to choose plants that do well in lower light during the winter months and where those crops will not be transplanted outdoors.
Best Vegetables to Grow in Winter
If you’re hoping to grow greens during the colder months, then stick to the following vegetables:
- Lettuces and greens
- Roots such as carrots, potatoes, and other cool loving plants.
- Brassicas such as broccoli, kale, and cauliflower
Another way to offset the cooler temperatures in late fall, winter, and early spring is to utilize a heating system with your greenhouse. A lot of people do this to grow a bountiful crop of winter vegetables. Doing so allows you to grow plants that are very sensitive to drops in temperature such as basil.
People use a variety of heating sources to warm their greenhouses and protect tender plants. Solar radiation is the natural way to keep your greenhouse warm. However, when the sun goes down so does the temperature in the greenhouse.
Water is a heat sink, and it warms slowly and cools slowly when not exposed to outside forces. In a greenhouse, a row of plastic jugs filled with water can be all that you need to keep your greenhouse warm during the night.
As the grower, if you want more control over the internal temperature of your greenhouse, consider adding a heating system. Electric or gas heaters are both examples of systems that allow you to have more control over the temperature fluctuations in your greenhouse.
People also use heat lighting systems but those can be expensive too, and unless you have a generator, anything electric will fail during a power outage.
There are many DIY types of heating projects that work well. Inverted flower pot radiator heaters are simple to build and candle-powered. Old cast iron wood stoves are also a great tool and easy to install.
The bottom line is that you have options when it comes to heating a greenhouse and that means you can utilize the benefits of a greenhouse in many adverse climates.
So, What Should You Grow in a Greenhouse?
The answer to that question is highly subjective. If you are considering a greenhouse as part of your food production and food storage system, then start the process by considering what your growing goals are and how to apply a greenhouse as a tool to increase harvest yield.
Check out the BDS post “The 13 Best Staples To Consider For A Survival Garden This Spring” for some ideas on what to plant or “High Yielding Crops For The Prepper Garden”.
Greenhouses come in all sizes from small to commercial. There are many greenhouse kits available on the market and as many if not more DIY options.
In closing, a word of caution. Be sure to consider the environment in which your greenhouse will be located. Whichever type of greenhouse you choose, make sure that it is structurally sound enough to stand up to heavy winter conditions. Snow is heavy, and under its weight, roof supports bend and break.
The wind is strong, and if your greenhouse is not assembled correctly or anchored accordingly, the wind can damage it. Also, consider drainage and flooring options carefully so that rain and flooding are not an issue.
Regarding the warmth for your plants, be sure to insulate your greenhouse and make it as energy efficient as possible. You want to make sure seams are well-sealed so that internal heat does not bleed off into the outdoors.
Like any tool, a greenhouse must be in good working order for you to obtain all the benefits the come with it. These are excellent tools that help to increase food production and enable you to take more control over the food you consume today and the food that you store for tomorrow’s usage.
What have you done to improve your vegetable crop? For some great greenhouse kit options check out this post.