What to Grow in a Greenhouse (Best Options for Year-Round Gardening)

A greenhouse is a great way to grow plants all year round, no matter what the weather is like outside.

It helps create the perfect environment for your plants by allowing you to control factors like temperature, light, and humidity.

This means you can grow a wider variety of plants and enjoy fresh vegetables, herbs, and flowers even during the colder months.

If you're curious about why every gardener should have a greenhouse—especially a raised bed greenhouse—check out our guide for more inspiration.

In this article, we’ll explore some of the best plants to grow in a greenhouse. These plants are easy to care for and will help you make the most of your space throughout the year.

Lettuce

Lettuce can be a bit challenging to grow in a greenhouse because it doesn’t handle temperature changes well.

If it gets too warm, lettuce “bolts” (which means it goes to seed), and the leaves turn bitter and less tasty.

To avoid this, try to keep the greenhouse temperature between 55–70°F. Lettuce doesn’t do well if it gets much hotter.

Some gardeners use shade cloth during hot weather. This helps keep the plants cooler and less stressed, so they grow better without bolting too quickly.

Another good tip is to pick the outer leaves regularly. This keeps the plant growing fresh leaves and lets you enjoy a steady supply of greens for longer.

By doing this, you not only get more lettuce but also help the plant stay healthy.

Cucumbers

Cucumbers grow really well in a greenhouse as long as you give them the right amount of warmth and moisture.

They thrive when the temperature stays between 75–85°F and require the soil to remain moist (but not soggy). If the soil dries out too much, the cucumbers can taste bitter, so watering regularly is essential.

Cucumbers do better when they have room to climb. If they are left to sprawl on the ground, they can develop mold or mildew because the leaves retain too much moisture.

Using a trellis or similar support for them to grow on works great. It improves airflow, helps prevent diseases, and saves space in your greenhouse.

Keeping the plants off the ground also helps with watering.

Like I said, they need moisture, but you don’t want the soil to dry out completely between watering (if it does, the cucumbers might end up bitter). 

Kale

Kale doesn’t need much attention but still gives you plenty in return. It grows really well in a greenhouse, especially when the temperature stays between 45–75°F.

It thrives in cooler weather, making it a great choice for those chillier days.

Kale grows better when you give it some space. If the plants are crowded, the leaves tend to be smaller because they don’t have enough room to spread out and grow.

One great thing about kale is that it keeps growing as long as you keep picking the outer leaves.

When you pick, the plant continues producing new leaves from the center, making it seem like it’s always ready to give you more. This means you can keep enjoying fresh greens for a long time.

Another advantage of kale is that it can grow all year round with proper care, so you can have fresh kale even in winter.

Kale is one of those plants that just keeps going with the right care. You don’t need to replant it each season, and it’s easy to look after while providing plenty to harvest.

Spinach

Spinach can be a bit sensitive, especially when the temperatures fluctuate a lot.

Gardeners sometimes let the greenhouse get too hot, which causes spinach to bolt (meaning it goes to seed and the leaves turn bitter).

It can be frustrating, but if you keep the temperature between 50–70°F, you’ll be fine. I’ve also read that spinach likes steady watering, but it’s important not to overdo it.

Just keep the soil moist, but not soaking wet (too much water can cause problems).

The biggest issue I’ve seen with spinach, though, is powdery mildew.

It’s challenging because it tends to show up when the air in the greenhouse is too still (the lack of airflow lets moisture build up).

You can improve airflow, and it really helps keep the mildew away. A simple way to do this is by making sure the greenhouse has good ventilation.

The good thing about spinach is that it grows pretty quickly (so you won’t have to wait too long for fresh greens).

If you take care of it and manage the temperature and moisture properly, you can have spinach ready to harvest in just a few weeks.

Radishes

Radishes are one of those plants that grow fast and are easy to take care of, and they do even better in a greenhouse.

When the temperature stays between 50–70°F, they can grow really quickly (sometimes in just a few weeks).

One thing you should know when growing radishes is that if you plant them too close together, they don’t develop properly.

The roots stay small and often end up misshapen (they don’t have enough space to grow the way they should). So, it’s best to space them out to give them room to grow.

Radishes also love steady moisture, but it’s important not to overwater them. If the soil is too soggy, the radishes can end up bitter (which is definitely not what you want).

If you get the spacing and watering right, radishes are a great crop to grow.

They’re perfect for a greenhouse where you can control the environment, and they’re ready to harvest before you know it.

Carrots

Carrots might be challenging to grow, especially when it comes to preparing the soil.

I’ve seen a lot of people get frustrated with deformed carrots, and it usually happens because the soil is too heavy and compacted (this makes it hard for the carrots to grow properly).

In a greenhouse, though, you have a much better chance to prepare the soil just right. The secret is loose, well-drained soil, and a greenhouse makes it easier to create that kind of environment.

Another thing I’ve learned about growing carrots is that thinning the seedlings is really important.

If you don’t thin them out, the carrots won’t have enough space to grow and will end up small or stunted (it might feel like a waste to pull up some of them, but it’s worth it for better carrots).

And don’t forget about watering. Carrots need consistent moisture to grow well.

If the soil dries out too much and then you water it heavily, the carrots can crack (which makes them look less appealing).

So, consistency with both soil and watering is really important to get the best results.

Tomatoes

Tomatoes are one of those plants that can either thrive or struggle, depending on how you take care of them in a greenhouse.

Some gardeners get really excited about their tomato plants, only to end up with weak plants because they didn’t provide enough light.

Tomatoes need full sun, so it’s important that your greenhouse gets plenty of light. If it doesn’t, you might need to use grow lights (this can help give them the light they need to grow strong).

Temperature is another critical factor to consider. Tomatoes do best when the temperature stays above 50°F. If it’s too cold, they won’t grow properly, and if it’s too hot, they won’t set fruit correctly.

You’ll need to find the right balance (which can be tricky, but it’s worth it once you get it right).

You’ll also want to give tomato plants some support. Without cages or stakes, the plants won’t be able to hold up the weight of the fruit, and they might break.

Using support helps keep the plants healthy and prevents them from falling over (so they can focus on producing fruit instead of struggling to stand).

If your tomato leaves are turning yellow, check out this guide for tips and solutions to prevent it.

When they’re well cared for, tomatoes can give you a great yield (it’s a bit of work, but the reward is definitely worth it).

Peppers (Bell, Chili)

Peppers are easy to grow as long as you provide the right conditions, but I’ve seen some people run into problems with them in greenhouses.

They need steady warmth, usually between 70–80°F, and they definitely don’t like sitting in waterlogged soil (so it’s important to make sure the soil drains well).

Peppers are heavy feeders, meaning they need plenty of nutrients to grow well.

So don’t hold back on the fertilizer (a little extra feed goes a long way). Some gardeners forget this, and their plants end up smaller or don’t produce as much as they could.

Peppers can be a bit slow to start, and it’s easy to get impatient when they seem to take forever to grow, but once they get going, they’ll start producing a lot.

And don’t forget to keep an eye out for pests. Aphids really like peppers, so it’s a good idea to check your plants regularly (catching pests early can save you a lot of trouble later).

Onions

Onions need a lot of light to form good bulbs, so it’s really important that your greenhouse gets plenty of it (without enough light, the bulbs won’t grow properly).

When it comes to temperature, onions are pretty flexible. They do well in a range of 50–75°F, so you don’t have to worry too much about getting the temperature just perfect.

The biggest problem with growing onions is overcrowding. If you try to fit too many onions in one space, they won’t have enough room to grow properly.

So, make sure you plant them far enough apart to give them room (it might seem like a lot of space, but it makes a big difference).

Watering is important too. Onions like consistent moisture, but you don’t want them sitting in soggy soil.

Once you get the spacing and watering right, onions are pretty low-maintenance. They just need enough light, the right amount of water, and space to grow.

After that, you’re good to go.

Herbs (Basil, Parsley, Cilantro)

I’ve read about many people having trouble with basil (it tends to bolt).

Too much moisture can cause mold and other issues, and basil really doesn’t like that (it can make the leaves unhealthy or even kill the plant).

Having good airflow and watering at the base of the plant (instead of getting the leaves wet) really helps prevent this.

Parsley and cilantro are a bit easier to grow, but they still need steady temperatures around 65–75°F and soil that drains well.

With cilantro, it tends to bolt quickly, so it’s a good idea to pick it early if you can (that way, you can enjoy the fresh flavor before it changes).

What’s lovely about herbs is how quickly they can fill your greenhouse with fresh flavors (once they get going, it’s amazing how much you can harvest).

They’re easy to take care of, as long as you provide the right care, and they’ll keep giving you fresh greens to use in cooking.

Broccoli

Broccoli loves a cool environment, and in a greenhouse, you can control the temperature to make it just right.

If it doesn’t get enough moisture, the heads won’t form properly (they’ll be smaller or loose, instead of nice and tight).

One thing to note when growing broccoli is that it needs enough space, just like the other veggies mentioned above. If you crowd the plants too much, the heads won’t form the way they should.

Broccoli might take a bit longer to grow than some other crops, but once it’s ready, it’s totally worth the wait.

You get those big, fresh heads that are perfect for cooking (and the taste is always better when you’ve cared for it well).

Brussels Sprouts

Brussels sprouts take time to grow, and they do best in a greenhouse where the temperature stays between 50–75°F.

They need a lot of space, so overcrowding is a big mistake.

Some people plant them too closely and end up with smaller sprouts that take forever to mature (they don’t have enough room to grow properly).

One great thing about Brussels sprouts is that they mature from the bottom up. This means you can start harvesting the larger sprouts first and leave the smaller ones to grow (which is great because you get to enjoy them bit by bit instead of all at once).

It’s a long wait, but if you’re patient, they’ll provide a steady supply of fresh sprouts throughout the season.

When properly spaced and cared for, they’ll reward you with plenty of sprouts to enjoy over time.

Garlic

Garlic takes its time to grow, but once it’s ready, you’ll get delicious bulbs.

The most important thing for garlic is the soil. It prefers soil that drains well (you don’t want it to get soggy).

If the soil stays too wet for too long, it can cause the garlic to rot, so water it regularly (but don’t overdo it).

Garlic also benefits from a little extra food. Using compost or a good fertilizer helps it grow strong (and gives you better bulbs).

Though it takes time, garlic is easy to care for once you get the soil and watering right.

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