Submitted by Christy Belvin

Tomatoes Horticultural Hint (printable pdf version)


 The tags in tomato sets have helpful, informative labels, and some of our local garden centers have a master sheet with descriptions of the varieties they carry.

 Whether the plant will grow as a vine (Indeterminate) or grow more like a bush (Determinate),

  • What size fruits it will produce (cherry to large)
  • How many days from planting until the fruits mature,
  • Resistance it may have to specific diseases, and something about its flavor.

Two Distinct Growth Habits:  Determinate  and  Indeterminate. 


The mature size is limited. It grows into a bush about 3 ft. tall, and all the fruit ripens at approximately the same time.

  • Helpful if you want a large quantity all at once for canning or freezing.
  • Since many Determinate plants stay under 3 ft. high, they can also be ideal for the small-space gardener or for growing in containers.
  • To get several nice harvests, you can combine Determinate varieties that bear early, mid, and late season crops.

 Some Determinate names and days to maturity: Beaverlodge/55, Ultra Sweet/62, Northern Delight/65, Patio Picnic/65, Patio Princess/68, NH Surecrop/78, and Roma75.


  • The majority of tomato varieties, including most heirlooms and most cherry types, are Indeterminate.
  • The plant is a vine that keeps growing indefinitely throughout the growing season and produces tomatoes over an extended period.  
  • At any one time there can be fruit maturing and new flowers forming.
  • Because the plant gets so tall, it requires sturdy support like a stake, trellis or cage.
  • The tomato expert at Johnny’s Seeds recommends pruning an Indeterminate tomato plant to 2 main leaders (or main stems) on either side of the first flower cluster.
  • Then every week or 10 days during the growing season, continue to prune out all suckers in the leaf axels between the main stem and a branch when they are 2-3 inches long.
  • Pinching out the suckers increases fruit yields and gives better air circulation.
  • Another recommendation is to pinch off the growing tips about 30 days prior to the first frost.  This puts the plant’s energy into fruit development rather than more leaf growth.
  • Note that most Indeterminate tomatoes require tall support systems, but even Determinate varieties can benefit from support even though they generally top out at three feet.


Because of their smaller size and growth habit, Determinate varieties are better suited to container culture. You can grow Indeterminate tomatoes in containers, but they will need support and pruning.  And use container/potting mix, not regular garden soil which will compact in a container.

Some Indeterminate names and their dates to maturity:  Jet Star/72, Cherokee Purple/72, Green Zebra/75, Big Boy/78, Brandywine/78, Rutgers/78, Beefsteak/80, and the cherry types Sun Gold/55+ and Sweet 100/70. 

Semi-Determinate:  Early producing varieties like Celebrity and Early Girl with 72 days to maturity are also Indeterminate. However since they tend to mature earlier and die back before the end of the season, they are sometimes labeled Semi-determinate.

Heirlooms or Hybrids:  Heirlooms are flavorful older varieties, usually Indeterminate, and open-pollinated with seeds that can be saved from one season to the next.  Hybrids are generally faster growing and more disease resistant than older varieties.

Days to Maturity: 

Each variety has a specific number of days between the date you plant the set and the date the first fruit will ripen.  It can be as few as 55 days to as much as 90 days.  In New Hampshire where our growing season is relatively short, you may want to look for varieties with shorter days to maturity.

 Disease Resistance: 

Tomatoes are subject to a great number of diseases and insect pests.

You may see the letters V, F, and/or N on the plant tag, especially in hybrid varieties.  This means that the variety has been bred for disease resistance to Verticillium Wilt, Fusarium Wilt, and/or Nematodes.



 Soil: rich, fertile, well-drained soil with plenty of organic matter.  Preferred pH of 5.8-7 (slightly acid).

 Exposure:  Full sun,  8-10 hours!!  with good air circulation, but out of strong winds.

 Temperature:  The nighttime air temperatures should be consistently above 50 degrees F, and the soil temperature should have warmed to at least 55 degrees F before you plant your sets.

 Crop Rotation:  Move annually.  Don’t plant tomatoes where you’ve grown tomatoes, peppers, eggplant, or Irish potatoes in the previous two years because of soil borne disease.


Keep the soil evenly moist so the roots never dry.  If the soil dries out completely, the roots become unable to access calcium in the soil which is a cause of blossom end rot.  Plus wide fluctuations or inconsistency in watering can cause tomatoes to split open.  Water in a way that avoids wetting the foliage.


Tomatoes are heavy feeders, but if they get too much nitrogen they will produce more leaves and less fruit.

Use tomato food or 2 cups of half-strength fish emulsion every two weeks once the flowers start forming fruit.

With commercial fertilizers, look for N-P-K numbers like 5-10-5 or 5-10-10.  Organic fertilizers will have N-P-K numbers like 3-4-6, 5-6-5, or 5-6-6.


Mulch of straw, salt marsh hay, compost, paper or plastic applied once the soil has warmed up will help suppress weeds and conserve moisture.  Mulch prevents soil borne disease organisms from splashing up onto the leaves during rain storms

 Ways to Avoid Spreading Disease:

Avoid wetting the foliage when watering.

Don’t handle tomato foliage when the plant is wet.

Use mulch to keep disease spores from splashing up from exposed soil onto foliage.

Have good air circulation.

Sterilizing previously used supports and ties,

Use crop rotation.

There is an excellent book in the Amherst Library — “Rodale’s Vegetable Garden Problem Solver” by Fern Marshall Bradley that gives in-depth descriptions of disease and insect symptoms and solutions.

Choosing sets:

Avoid root-bound seedlings, ones with yellow leaves, or ones that are already starting to flower.  These plants are stressed.  Buying tomatoes in 4” pots or larger may help avoid this problem.  Small sets will easily catch up to larger ones once planted if the soil conditions are right.


Bury the stem all the way up to the first set of true leaves.  New roots (“adventitious roots”) will form underground from those little bumps you see along the lower sections of the stem before you bury it.

Putting a protective collar around the stem will help protect it from cutworms that may be living in your soil.


Install your stake or cage right away at planting time to avoid damaging the plant once it has begun to grow.  It is advisable to disinfect previously used stakes or cages by washing them with a 1:10 ratio of bleach and water.

Monitor the plant weekly and use soft ties as necessary to support the vine.

Pruning:  Pinch out suckers on Indeterminate varieties.  Little or no pruning is advised for Determinate varieties because you may be removing the fruiting branches (called “flower trusses”).  On either type, pinching out the set of leaves directly below the flower truss can improve air circulation.

You can watch a helpful video on Pruning Tomatoes and other topics on

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