Growing tomatoes

By Steve Reiners, Professor and Chair, Horticulture Section, Cornell University, Cornell AgriTech. This is part of a series of columns that he wrote about vegetable gardening during the pandemic that ran Spring-Summer 2020. Read more articles from 2020 | Read later articles in this series.

May 8, 2020

This week we’re talking tomatoes, and I thought I’d start the column with a question: Is a tomato a fruit or a vegetable?  Go ahead, ask your in-house expert.  The answer is below.

Tomatoes are the most popular vegetable grown by gardeners.  And why not?  They’re easy to grow, prolific producers, and taste great.  They do well in containers on patios and decks.  You could harvest 15 to 25 nice slicing tomatoes from a single plant or hundreds of small cherries.

Tomatoes love warm temperatures. So, it’s still too early to plant outside, unless you plan to cover them and protect from cool nights.  Although we’re getting close to our frost-free date, usually around May 15 to 20, tomatoes won’t grow well when night temperatures fall into the 40’s.


As far as varieties, you have thousands to choose from.  They vary in color, fruit and plant size, earliness, disease resistance and many other factors.  Good varieties for this area include:

  • Cherry types such as Sungold.
  • Grapes such as Juliet and Sugar.
  • Large fruited-types like Better Boy, Big Beef, Celebrity, and Supersonic.
  • Heirlooms like Brandywine and Cherokee Purple.

Heirloom varieties are traditional varieties that have been preserved by gardeners for generations and often have great flavor.

New to the market in 2020 are the Galaxy Suite of grape tomatoes, bred by my Cornell colleague, Phillip Griffiths. They include five varieties with unique shapes and colors, and all have great taste.  Certainly worth a look in your garden.

Over the last ten years, we’ve been dealing with a fungal-like disease called Late Blight.  It’s the same disease that caused the Irish Potato Famine 170 years ago. It’s still with us today and is just as devastating to tomatoes.  If we have a sunny, dry and hot summer, we won’t have a problem.  But if it’s cool, cloudy and wet – watch out.  You might want to include some tomato varieties that are resistant to this disease as well as other common diseases.  Cornell breeder Martha Mutscher-Chu and Plant Pathologist Meg McGrath have bred and trialed some excellent new varieties.  Iron Lady was one of the first but Stellar and BrandyWise have improved flavor.

Acquiring plants

Unless you started tomatoes indoors 6 weeks ago, you will need to purchase your plants at a local garden center this spring.  Fortunately, most are open in NY and are carefully following social distancing recommendations.  You won’t have the huge number of varieties to choose from that you would if you started the plants yourself, but you will find dozens to choose from.

Tomatoes are identified as either determinate or indeterminate types.  Determinates are smaller more compact plants that take up less room.  Indeterminates are big plants that usually produce more fruit but will likely need to be pruned to keep under control.

Varieties in seed catalogs always include the days to harvest (DTH).  That is the number of days from transplanting until you get the first ripe fruit.  A 75-day variety planted June 1, will theoretically produce ripe fruit 75 days later, around August 15.  The DTH is useful in comparing varieties but it assumes perfect tomato growing conditions.  Often that 75 day tomato could take 80 or 82 days in cooler weather.


Tomatoes are unique in that they can develop roots all along the stem.  When transplanting, dig a hole at least twice the size of the root ball and sprinkle in compost.  Plant the tomato either horizontally or vertically in the soil, with only the top two leaves above the ground.  Remove the leaves below. Water the root ball with a soluble fertilizer that’s high in phosphate (the middle number on a fertilizer label).  Space the plants at least 18 inches apart in the row, two feet is even better.  Leave four feet or more between rows.

We’ll talk more in future columns about staking and pruning tomatoes.  But for now, think about supporting the tomatoes on stakes or cages to keep them growing upright rather than sprawling on the ground. You will get better production and less disease when you keep the plants up off the ground.

Right now in the garden, there is still time to plant spinach and peas.  All the root crops can be planted, as well as cole crops like cabbage and broccoli, and salad crops like lettuce and Swiss chard.  Normally sweet corn could go in by now, but our soil temperatures are still too cold, so let’s wait a week for that.

Fruit or vegetable?

Now back to the “are tomatoes a fruit or vegetable” question. In 1886, an importer named John Nix landed a load of West Indian tomatoes in New York.  The Customs agent levied a 10% duty, as specified by the Tariff Act of 1883.  Nix claimed his tomatoes should be duty free as the tariff applied only to vegetables.  By the botanical definition, a tomato is a fruit since it contains seeds.  The case finally reached the Supreme Court in 1893 when Justice Horace Grey said, “Botanically speaking, tomatoes are the fruit of the vine, just as cucumbers, squashes, beans, and peas.  But in the common language of the people, all these vegetables are usually served at dinner, in, with, or after the soup, fish or meat, which constitute the principle part of the repast, and not, like fruit, generally as dessert.”  Nix paid up.