Growing tomatoes in a cold-climate without a greenhouse

Added on 07 May 2021

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Growing tomatoes in a cold-climate without a greenhouse

As the majority of gardeners in America are planting their seeds and enjoying time in their gardens, many of us are cooped up in our houses, snow falling outside, as we continue to pour over seed catalogs and dream of warm weather. Living in a short-season/cold climate might make you feel like you can't grow tomatoes without a greenhouse. We used to think that ourselves. We live in the high-altitude Rockies, where we have a 10-12 week growing season frost-to-frost, and our nights during the summer regularly dip down to the 40s Fahrenheit. But over the years we have learned through trial and error, and ideas from others, that it is absolutely possible to grow and enjoy tomatoes from a short-season/cold climate garden without the use of a greenhouse.

Harvested tomatoes by Kat Ludlam

Pick the Right Varieties

The first step to success is to choose good varieties for your climate. It is so easy to get caught up in the beautiful seed magazine and want to try a little of this and a little of that. You can try different varieties, just make sure you are picking the fastest-to-harvest varieties that tolerate the colder temperatures. We have found that the varieties that originated in Siberia and Russia are a good place to start and they generally do very well for us. Our favorite varieties include Mount Roma, Mother Russia, Russian Yellow, and Long Keeper. Seeds Trust has a great selection of tomato varieties for cold climates.

Start Indoors

When you have a very short growing season, starting your plants indoors is a necessity. We found that using a light shelf unit worked much better than our windows. My husband was able to build us one pretty easily and it saved us a lot of money. I start our tomatoes indoors about 10 weeks before our average last frost.

Start indoors with plant lights by Kat Ludlam

Once they have their first set of real leaves, we transplant them to bigger containers and continue to keep them under the lights.

Fragile seedlings by Kat Ludlam

A week before they are going to be planted outdoors, we harden them off. To do this we wait until the sun is up and warm and then we place them outside in a splotchy shaded area. The first day they stay out for about 30 minutes, the second day an hour, and so on as we work them up to being able to handle a full 8-hour day out in the splotchy shade. We bring them in if the weather is windy, or it starts to rain. And when they come in, they are no longer under the lights, they are just next to windows in the house. By doing this they will become "hardened off" and thus be able to survive outdoors better.

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