Can You Grow Vegetables Year Round in a Greenhouse?

As the seasons change, those of us who are new to greenhouse gardening may have questions about what growing vegetables looks like year-round.

To grow vegetables year round in a greenhouse, you’ll need to adjust your lighting, temperature, watering, and what types of vegetables you grow. However, you’ll need to adjust your greenhouse conditions depending on the time of year, how much sun your greenhouse gets, your growing zone, and what vegetable varieties you want to grow.

This may seem like a lot of work, but by the end of this post, you’ll have all the information you need to keep up a successful greenhouse all year long!

Getting Started: Pick Your Vegetables

The best place to start is to decide which vegetables you want to grow. I’ll discuss seasonal vegetables later on, but the most important thing here is that you’re growing things you like–and varieties that’ll grow best for your conditions & time of year. You’ll be more successful if you’re growing things that you enjoy eating. If you plan to sell your produce, ask your customers what they’d want to buy.

Once you pick out your vegetables, you can group them together based on how they thrive. If you plant vegetables that grow best in similar conditions, you’ll have an easier time controlling your lighting, heating, humidity levels, and amount of watering.

Although eating and growing seasonally has recently become trendy, it’ll also help you maximize your greenhouse each season. If you grow vegetables that thrive in the season you’re experiencing, you’ll spend less on heating, cooling, and lighting.

Below are some examples of different vegetables that grow best during each season:

This list is not exhaustive, and there are many vegetables that can thrive in several seasons.

The important thing is to optimize each growing season by choosing vegetables that naturally thrive during those specific times of year. Since you’ve already made your list of what you want to grow, you can research those vegetables’ growing seasons and then group them accordingly.

Containers and Soil

Once you have your vegetables picked out, you can select your containers and your soil.

You’ll want to make sure your containers can drain excess water and that they are spacious enough for your plants to grow in unobstructed. The type of growing container will directly depend on which vegetables you have chosen to grow and whether or not you will plant them directly into the ground or pot them.

If you’re just starting out, potting is a good way to go because it does not require additional building. You can buy potting trays into which you can place your pots for easy transportation, and the kind of pot you buy is up to you. Fiber, plastic, biodegradable wood—it’s really about preference! So long as your plants have room to grow, you have picked the right pot.

You’ll also want to use good, fertile soil–preferably with compost mixed in. Compost not only adds fertility to your soil, but it also holds heat in the winter, which will help you save on the cost of heating!

Controlling the greenhouse environment: lighting, temperature, humidity, and watering

From here, you can start preparing your greenhouse for seasonal changes by monitoring lighting, temperature, humidity, and watering.

Lighting

First up: lighting. In the summer, you will rely mostly on the sun for lighting, so you can keep your lighting system turned off or wait to install it until the days start to get shorter. In fall and winter, your lighting system will be key for your plants’ success.

The first step is to take advantage of the natural light you do have available. Position your plants in places where they will receive the most sunlight during the day—even on cloudier days, the plants will still benefit from natural light. Then, you will rely on your lighting system to give your plants the extra light they would receive naturally during the summer.

I’d recommend installing LED lights because they are low cost but high output. Especially if you live in a place with few sunny days during the winter, you’ll want to have an effective lighting system without breaking the bank. You can also purchase warming lights that will provide the plants with both the extra light they need and the extra heat.

Monitoring temperature in your greenhouse

Next up is your greenhouse’s temperature. Keeping a good thermometer in your greenhouse—one that records the temperature inside the greenhouse and outside—is the easiest way to make sure things are as they should be. It’ll help you monitor the temperature, and then you can  increase heat or cool your greenhouse as needed, which will be really important for the health of your plants!

In the winter, you’ll need extra heat, and depending on where you live, you may need heat your greenhouse during colder parts of fall and winter. Some gardeners choose to have a cooling system as well for the summer, but many people just use vents during the warmer months to circulate the air. In the winter, though, you will want to make sure you have a heating system in place.

Installing insulation will help you save money on electrical heat. You can use bubble wrap along the walls of your greenhouse for insulation. From here, depending on how cold it gets where you live, you will likely want to use a heating system as well.

Like I mentioned above, if you grow vegetables seasonally you won’t need to rely on a ton of heat in the winter, because your vegetables will thrive in cooler weather.

The general idea is to keep your greenhouse cooler in the summer and warmer in the winter, just as you would with your own house.

Humidity

Next: humidity. The amount of humidity your plants need will depend on the type of plant and the climate in which you live. If you live somewhere dry, it’s best to grow plants that thrive in dry weather so you won’t have to create so much humidity. The same goes for living in a humid climate—since the air will already be humid, it will make it easier on you if you grow plants that thrive in humid climates.

Misting is the easiest way to provide humidity. As the seasons change, you’ll notice the need for more or less humidity just by feeling the moisture on the plants and with your own senses. Trust me: you’ll know if your greenhouse is too humid just by spending a few minutes inside!

Watering

Last but not least is watering. Your plants will need more water in the summer and less in the winter. So, if you have an automatic watering system, you can just adjust it accordingly.

If you plan to water manually, you’ll notice that you need to water less in the winter months. The best way to know if your plants need water is to touch them! Feel the soil, and if it’s even damp, the plants have enough water–basically, if you touch the soil and your finger has bits of soil on it, you don’t need to water.

It’s also important to remember that different plants need different amounts of water.

This is one advantage of manually watering: you will be able to give each plant the amount it needs.

However, automatic watering systems do save time and there is less responsibility on your shoulders to keep track of watering. If you’re using an automatic watering system, choosing vegetables that need similar amounts of water, or adjusting the water for separate zones will solve this problem for you!

You’re ready to grow!

You’ve just absorbed a lot of information, but the main idea is that you’ll be most successful if you work with the environment you live in and use the different climates where you live to your advantage.

Gardening year-round takes practice, and the best way to become a great gardener is to try things out, make mistakes, decide what to change, and keep moving. The more mistakes you make, the more lessons you learn, and the better things will turn out when you try again!

Related Questions

What are the best materials for a year-round greenhouse?

If you’re just beginning the process of building a greenhouse or are updating your current greenhouse, the materials you choose will make a big difference. If you get a lot of precipitation where you live, weather-proof materials will last longer and be more cost-effective in the end. Both glass and thick treated plastic are great options for longevity.

How do I make a growing schedule?

I’d recommend planting your winter plants in December or January, your spring plants in March, your summer plants in April and May, and your fall plants in July and August. Generally, plants that thrive in cooler weather will have longer germination periods than warm weather plants.

Knowing when to start planting will be one of your keys to greenhouse gardening success. After you’ve picked out which vegetables you want to grow, do some research on their germination periods. This will help you decide when to start planting.

How do I protect my plants from frost?

You can blanket your plants in one or two layers of horticultural fleece through the night, making sure to remove it in the morning so the plants don’t overheat. You can also use horticultural fleece as part of your regular heating plan to save money on electricity!

Your heating system should protect your plants during most winter nights, but on particularly cold nights you may want some extra protection.