Out In The Greenhouse: These Warm-Season Crops Will Thrive

The list of food crops and flowers that do well in a greenhouse is endless. Seriously, it goes on forever. Being a first-time greenhouse grower, I’m just getting my feet wet, but so far, I’m amazed by how much my ‘she-shed’ has transformed my short growing season.

If you have a heated greenhouse, the world is your oyster, and there’s no shortage of what you can grow. Growers will cool greenhouses can take advantage of the free warmth from the sun during the late spring, summer, and early fall. Then, when temperatures dip, cool-season crops can take over. 

For now, here’s my list of five food crops that thrive in a warm greenhouse (from personal experience).

Are you looking for an easy crop to grow in the greenhouse? Look no further than tomatoes! These babies are super rewarding too, and if cared for properly, will deliver bountiful yields all season long. 

Many northern growers only harvest tomatoes from mid-July through August (in a good year). With a greenhouse, expect to extend the harvesting period by a lot, especially if the greenhouse is heated. My plants were loaded with green tomatoes by early June. 

The fun thing about tomatoes is there are so many varieties you can choose from that suit different greenhouse setups. You can grow them in raised beds, containers, grow bags, and hanging baskets. 

Depending on the size of the greenhouse, you might want to select more compact or determinate tomato varieties, so things don’t grow out of control. When the environment is right, tomatoes can quickly overtake a space. 

Be sure to water greenhouse tomatoes frequently and don’t leave them out until nighttime temperatures are warmer than 13°C (55°F).  

Peppers

Together, greenhouses and pepper plants are a beautiful thing. Never in all of my gardening years have I had peppers so early. I’m talking before July, and in my short growing season, that’s saying a lot. I owe it all to the head start they got in the greenhouse.

Whether growing bell or chilli peppers, they’re an excellent choice for pots and grow perfectly sitting on a greenhouse bench too. Be sure to keep them well-watered and give them a balanced fertilizer before they set fruit. 

Peppers are prone to aphid and whitefly infestations; the second you see one, get the plant out of the greenhouse to protect your other crops. 

Cucumbers

Cucumbers grow like a weed in the right environment. We had a couple of heatwaves in June, and my greenhouse cucumbers grew leaps and bounds in just a few days, especially compared to the ones I have outdoors.

This crop is perfect for the greenhouse because they can grow vertically. Put them next to a trellis and watch them reach for the sky.

They need temperatures of 25°C to germinate, and after that, temperatures should never dip below 15°C. It’s a good idea to choose a cucumber bred explicitly for greenhouse growing, and avoid planting more than one variety to prevent cross-pollination. 

Keep the greenhouse well-ventilated to avoid issues with powdery mildew. 

Eggplants

Having grown eggplants outdoors in a short growing season, I can tell you there’s a big difference when moving this crop into a greenhouse. The foliage is lush, and I have more flowers on each plant than ever before. I had little fruit starting to show before July, thanks in part to some scorching weather. 

Eggplant loves the warmth and sun. I’ve placed mine in dark 5-gallon pots against the hot windows, an environment that seems to be a recipe for success. Most varieties are low and bushy, making them perfect for smaller spaces.

Remember; eggplants need temperatures of 25°C to germinate and thrive in warm soil. 

Beans

Is there anything easier than growing beans? Most varieties don’t even need pollination to deliver high yields!

Like tomatoes, I love experimenting with the different varieties of beans out there. This year, I’ve chosen “Dragon Tongue”, a high-yielding bush variety that does very well in containers and is thriving in my greenhouse. 

It doesn’t take long for them to sprout. Plant a seed and expect to see it emerge within a few days. You can start beans in the greenhouse at the end of the winter to harvest by the spring. 

Plant a succession crop every few weeks. Beans grow in both warm and cool greenhouses, so expect to enjoy them for months to come. 

EDITOR’S NOTE: These two resources are with me through all of my greenhouse growing ventures:

The Greenhouse Gardener’s Manual (Roger Marshall)

Greenhouse Vegetable Gardening (Inger Palmstierna)