Dwarf Indeterminate Tomatoes are Ideal for Home Gardeners
Feb 6, 2022
The newest category of tomatoes, dwarf indeterminate, provides home gardeners with smaller-sized tomato plants that are ideal for patio or deck. Before sharing more about this tomato variety, it’s helpful to understand the three major categories of tomatoes: 1) Determinate, 2) Indeterminate and 3) Dwarf indeterminate.
Three Varieties of Tomatoes
Determinate tomato varieties have a determined height and after a certain point, they stop growing. They have a compact bush habit and will usually grow from 2 to 4 feet tall depending on the variety and growing conditions. These varieties also have a determined fruiting period because they produce flowers and fruit mostly at the tips of their branches. After blooming they will not get any taller, and most vegetative growth will stop. They tend to produce a large crop over a short time period, usually around 3 to 4 weeks. After the main harvest, only an occasional fruit is produced, and the plants tend to die off.
Determinate types are never pruned because it would drastically reduce the harvest. Determinate tomatoes are popular with home gardeners as they can readily grow these tomatoes in large containers or in small gardens. Staking may be needed to support a large crop. Commercial canners also enjoy these tomatoes because the fruit tends to ripen all at once for more efficient harvesting. Favorite determinate varieties include ‘Celebrity’, ‘Bush Early Girl’, ‘Bush Beefsteak’, ‘Roma’, ‘Principe Borghese’, ‘Silvery Fir Tree’, and ‘Tiny Tim’ (a very short variety).
Indeterminate tomato varieties are tall. Their size is not determined and the vines will keep growing taller throughout the growing season. The production period is not limited to a brief burst of production; the tomatoes produce all season. Vines may grow to be 6 or 8 feet tall, or more. They should be tied to a substantial stake or supported with a stout cage. Indeterminate tomatoes may be grown in large containers, but again, they need to be staked or caged to support the vines and fruit. Some gardeners choose to prune to keep the vigorous vines within bounds.
Favorite indeterminate varieties include ‘Brandywine’, ‘Big Beef’, ‘Mountain Magic’, ‘Delicious’, ‘Matt’s Wild Cherry’, and ‘Sun Gold’. The number of indeterminate tomato varieties available is much larger than that of determinate varieties. The indeterminate varieties have a large and wonderful range of colors, shapes, sizes, and often intense, unique, complex flavors (especially in the heirloom or old-time varieties). However, their large unruly vines make it a challenge to grow in the small garden or on the patio.
Dwarf indeterminate tomato plants are unique in that they have a very thick central stem, leaves that are usually dark green and crinkly (rugose), and very compact growth. To me, they look as if a giant hand squished a larger tomato plant to a smaller size. The spaces between the leaves (internodes) are very short. Some people call these varieties tree-type tomatoes or indeterminate short internode (ISI) tomatoes. Height varies from 2 to 4 ½ feet. Their fruiting habit is similar to the indeterminate varieties in that they will continue producing tomatoes until frost kills the plant. The fruit yield may not be as much as the true indeterminate tomatoes, but dwarf indeterminates may be grown closer together and in large size pots (5 gallons or larger).
Dwarf indeterminates should be staked because good fruit production tends to make these plants top-heavy. Pruning is not recommended. By growing different dwarf indeterminates you can get good production and an increasingly large choice of colors, sizes, shapes, and fine flavor. The dwarf indeterminate tomato varieties are not yet widely available in nursery centers. If you want to try some dwarf indeterminates this year, your best bet might be to grow your own. Varieties worth trying include ‘Perth Pride’, ‘Dwarf Wild Fred’, ‘Sleeping Lady’, and ‘Rosella Purple.’
The History of the Dwarf Indeterminate Tomato
In 1850 Alexander Livingston founded one of our nation’s first seed companies. Up to that time, tomatoes were considered poisonous by most of the general public. Livingston helped to popularize the tomato in this country, introduced one of the first reliable tomato varieties, ‘Paragon,’ in 1870, and went on to introduce 30 additional tomato varieties.
In a field of Livingston’s ‘Acme’ tomato, one unique plant was discovered and introduced as ‘Dwarf Champion’ by the Maule Seed Company in 1889. ‘Dwarf Champion’ produces 3 to 8-ounce fruit on tree-like, four-foot plants. In 1896 Livingston himself listed the plant in his catalog and described it as follows:
“A single plant of it was found some ten years ago (1886) in a field of our Acmes. It is well adapted for forcing in vegetable houses, because of its dwarf and compact growth, the plants growing stiff and upright, with stiff-jointed stems, the foliage of an unusually dark green color, thick and corrugated.” Tomatoville forum
‘Dwarf Champion’ was crossed with the largest tomato variety known at that time, the ‘Ponderosa,’ a red, meaty, 1-2 pound beefsteak variety. The result of this cross was the ‘New Big Dwarf.’ Fruit on the ‘New Big Dwarf’ weighs up to one pound and the dwarf, bushy plants are two to four feet tall. ‘New Big Dwarf’ was introduced in 1915.
These varieties are the first of an entirely new class of tomatoes, the dwarf indeterminates – they keep producing fruit continuously and grow like the indeterminates, but are not nearly as tall. Up until just recently, very few dwarf indeterminates were discovered or developed. Then in 2005, Patrina Nuske-Small of Australia corresponded with North Carolina tomato expert Craig LeHoullier. They considered the possibility of crossbreeding the existing dwarf indeterminate varieties with heirloom (indeterminate) varieties to produce new types of dwarf indeterminate varieties. The Cross Hemisphere Dwarf Tomato Breeding Project was born.
Flowers on a dwarf indeterminate plant are pollinated with pollen from an heirloom indeterminate plant. The resulting hybrid first-generation plants (called F1 plants by scientists) are all very uniform in all characteristics and are non-dwarf. It is not until the second generation, or F2 generation, that genetic characteristics start segregating out. The dwarf characteristic is a recessive (hidden) trait so, in the F2 generation, about 25% of the plants will be dwarf. Because other traits that the breeders are looking for may be dominant or recessive, continued selection goes on during each growing season. It takes from 7 to 10 generations to stabilize a new variety from the hybrid cross so that the seeds produce plants that are reliably true to type.
Dwarf Indeterminate Tomatoes Today
Dwarf indeterminate tomato seeds are now exchanged across the globe and two crops of tomatoes are grown each year. Volunteers worldwide are involved in breeding, carefully selecting the best plants, and working to stabilize the new varieties. Volunteers in the Northern hemisphere make selections of the most promising plants during the summer. Seeds from these selections are grown out in the Southern hemisphere during our winter, more selections are made, and the new seeds are sent north again. Volunteers are permitted to name promising varieties that they select. The cooperation cuts the development time for a new variety in half.
Over time, more than 250 volunteers have become involved. Today, crosses in varieties have been made, promising results have been selected and grown, and more than 30 new dwarf indeterminate varieties have been developed. They are all non-hybrid (open-pollinated) varieties. You may save seeds from any of this year’s dwarf indeterminate fruit to plant next year and the plants will grow true to type. The project continues and new varieties are expected to be introduced each year.
If you don’t find exactly the type of dwarf indeterminate tomato that you want, try your hand at creating your own. Remember, the dwarf tomato breeding project is all volunteer – no professional horticulturists or botanists are involved. Just regular tomato lovers and avid gardeners, like you and me.
If you have limited growing space, consider the dwarf indeterminate tomato. Below are additional resources to get you started:
Tomatoville.com is the command center for the dwarf tomato breeding project and all things tomato.
Nctomatoman.weebly.com is Craig LeHoullier’s website with information on new releases from the dwarf tomato breeding project.
Dwarftomatoproject.net is about the dwarf tomato project in Australia.
Epic Tomatoes by Craig LeHoullier is about all things tomato and serves as an excellent, well-written resource.
Plant Breeding for the Home Gardener by Joseph Tychonievich is a well-written starter book on plant breeding.
Breed Your Own Vegetable Varieties by Carol Deppe is a resource for more advanced gardeners. It addresses genetics and includes a list of excellent references.
Joe Baltrukonis (with thanks to my editors Jennifer Porwit and Marge Hols)
Ramsey County Master Gardener Volunteer
Illustration by Laine Porwit