Everything about tomatoes speaks of summer—their tart flavor, juicy texture, ripe, red color—oh, the joy! But before northern gardeners get to the first big, fat slice of tomato, they must plant, prune, water and care for their tomatoes. Over its 150 years of publishing garden information, tomatoes have been a frequent—sometimes controversial—topic. Here are some of our favorite tomato tips from the archives:
Remember: Tomatoes need sun and air circulation. Way back in 1899, August Wittmann of Merriam Park in St. Paul described his tomato techniques to achieve his goal of “early, smooth and large-sized fruit for the market.” Plenty of air and sun are necessities, he said. He planted his seedlings lower in the ground than they were in the pots in order to get a stronger root system.
Don’t rush planting. Whittmann never planted tomatoes out of their cold frame before May 20, and Duluth gardener Homer Hall recommended in 1951 that gardeners in northern Minnesota wait until at least June 1 to plant, possibly June 15 for best results. A tomato in cold ground will only sit and sulk, so don’t rush them.
Fertilize, but not too much. Whittmann set his tomatoes in a garden space that had been given “a liberal dressing of manure—8 bushels per 100 square feet—and each plant received a dose of 5-10-5 fertilizer at planting.
Mulch to reduce disease and keep plants moist. In MSHS’ “Good Gardener” series of books from the 1990s, Lawrence Rule recommended gardeners mulch their tomatoes to prevent them from going from over-wet to over-dry conditions (often a precursor to blossom end rot). He also recommended you not hoe around tomatoes after the first week because the plant has shallow feeder roots.
Choose varieties for a longer harvest season. Our season is short and some writers in MSHS publications recommended never choosing a tomato variety that takes more than 75 days to mature. We think you can push that, but the idea of choosing several tomato varieties with different maturity dates is a good one. Pick an early season tomato, such as a cherry or Stupice; two or more that are mid-season and maybe one or two big, long season varieties. Looking for some great tomatoes to try? Here’s a list from several years ago of heirlooms that do well in our climate and
With pruning the question is yield vs. quality vs. disease. Over more than 20 years, Dr. T.M. Currence periodically wrote about his studies of tomatoes that were pruned and staked vs. those that were not. In an article in 1961, he described results of three groups of tomatoes: one group was pruned and staked, one was staked but not pruned, and one was not pruned or staked. You can read it for yourself here, but the upshot was that there isn’t much difference in yield with staked and pruned vs. unpruned tomatoes, but staking tomatoes did seem to increase the size of fruits. Overall, pruning had little effects on the plants.
Prune heavily in small spaces. An article in Minnesota Horticulturist recommended that even in a very small garden, tomatoes be spaced at least 1 foot apart. Doing this, however, requires that the plants be pruned to a single stem. Remove all side shoots or branches before they are more than 4 inches long, and use a support strong cord that can be woven around the tomato to hold it steady.
Rotate tomatoes in the garden. Tomatoes are somewhat disease prone and many of the diseases are soil-borne. So it’s a good idea to move them around, according to Lawrence Rule. I have my tomatoes on a three year rotation so that they are never in the same space more than once every three years.