Greenhouse Tomato: So Many Tomatoes, So Little Space

Posted on March 26, 2021 | Categories: greenhouse tomatoes

greenhouse tomatoesGreenhouse tomato growers are rightfully confused when they see so many kinds of greenhouse tomatoes for sale. Karen Olivier, independent tomato breeder from the Secret Seed Cartel, estimates there are 20,000 kinds of tomatoes listed right now and she is adding to that number by breeding new tomatoes every year.

Olivier specifically likes heart shaped, multi-coloured, flavourful greenhouse tomatoes and her Northern Heart series of tomatoes are enjoyed across Europe and in high-end restaurants in San Francisco. If Covid sees you growing at home and missing travel, these tomatoes give you an exotic taste and appearance but from your own back yard.

I ordered and am starting forty kinds of tomato seed but when Ted buys some “crazy expensive” Tasti-Lee seeds he texts me right away. “Do I have room for one more plant?” As a gardener with limited space, I should say no. As a greenhouse grower with a wild enthusiasm for everything different, I say yes.

Tasti-Lee Tomato from West Coast Seeds

I have a big greenhouse, 16’ wide and 20’ long with a bed down each side. So, if I space plants a foot-apart I can squeeze in 40 plants, one of each kind. If I put the bush plants in pots outside or in hanging baskets, I can space out the indeterminate types or grow a few more. But there are just so many tomatoes available, it will take willpower to say no.





The greenhouse tomato is a passion for so many people. They bring memories of youth and dinners out and shared patio dinners with friends. Cherry tomatoes, like Super Sweet 100, sliced in half and served with Bocconcini cheese, fresh basil and olive oil reminds us of dinner with friends. Or large Heirloom tomatoes like Aussie, sliced into thick slabs and served on a toasted piece of bread reminds us of summer picnics. Making spaghetti sauce with one of the many Roma tomatoes or snacking on fresh-picked tomatoes right off the vine is divine.

Regardless of what you want to grow or why, March is the month to start your tomatoes in Northern regions. In a greenhouse you can start them a bit sooner but it is a combination of light and heat that yields the best fruit because tomatoes are a warm season crop and they prefer heat.

Here are some of the steps to success with tomatoes in your greenhouse. And if you want to try Karen’s Northern Hearts or Karma series tomatoes wherever you grow, order them from Artisan seeds:

Karen was a guest on my podcast so if you want to hear more about her breeding efforts and success, you can listen in here https://donnabalzer.com/s2-episode-6-breeding-new-tomatoes/

tomato gardening

Timeline for Growing the Best Greenhouse Tomato:

  • Start seeds mid to late March on a heat pad
  • Move plants 6” below grow lights after they sprout (in less than a week)
  • Transplant tomatoes when they get their first true leaves
  • Start fertilizing as soon as the tomatoes are transplanted
  • When the greenhouse temperature is reliably above 10 degrees C day and night move plants into the greenhouse (you can use a heater to push up this date.)
  • If the plants are leggy, too tall or floppy, remove the bottom leaves and plant them deeper into greenhouse pots or soil beds.
  • Like multivitamin pills for people, tomatoes like a number of nutrients in their fertilizer. I like a fertilizer with kelp and micro-nutrients and I mix it at half strength and water it in once a week.
  • Ideally, plants will be short and stocky. It they are thin they are either too hot, too overwatered, or under-fertilized. They may also need air movement so add a fan if all other ideas are considered and dismissed.
  • Once indeterminate plants are staked or tied to a string, side shoots can be removed and by the end of September, the top of the plant is also removed.
  • Gradually remove leaves below the fruit trusses. By the end of October, the plants should be almost leafless but with trusses of tomatoes to the top of the plant.

For more great tips from Donna, visit www.donnabalzer.com.

You can also read Donna’s gardening books: No Guff Vegetable Gardening with Steven Biggs and her just released Gardener’s Gratitude Journal:  Part Diary, Part Personal Growing Guide.

donna balzer