Also known as paste, roma or sauce tomatoes, plum tomatoes (Lycopersicon esculentum) are a meaty, oblong fruit with few seeds. Varieties come in yellow and red and are often used for canning soups and sauces, but many varieties also offer great taste straight off the vine.
About Plum Tomatoes
Plum tomatoes come in both indeterminate and determinate varieties. While determinate varieties only grow to a certain size and produce a set number of blooms, indeterminate varieties grow for as long as weather conditions support growth. For areas with limited space, or for gardeners looking to can sauces, determinate varieties are the best choice. All fruits mature within a short time period, giving growers a large harvest an once -- perfect for preserving large batches of canned goods. Because determinate varieties do not grow very large, plants require only staking or no support at all. Do not prune determinate tomato plants unless there is damage, and then only cut off the damaged vine to the nearest healthy stem with pruning shears sterilized with an alcohol wipe. Because they only produce a set number of blooms, unnecessary pruning will reduce fruit production.
For gardeners who want consistent production, indeterminate varieties are a better option. These varieties grow from the time they are planted until the first frost, so a sturdy support system, such as a cage made of the wire that reinforces concrete, is required. Pruning indeterminate varieties is optional. Remove suckers -- the stem that grows in the crotch between the main stem and a branch -- to keep tomato plants from getting too big. Remove any damaged branches, or those that are sprawling on the ground, at the closest healthy stem. Always sterilize shears with an alcohol wipe between cuts to prevent the spread of disease.
The Plum Regal (Lycopersicon esculentum 'Plum Regal') is a determinate plum tomato that matures in 75 days. For gardeners who want to add some color to the garden, the Golden Fresh Salsa tomato (Lycopersicon esculentum, 'Golden Fresh') is a determinate option that matures in 70 days and offers prolific harvests. The large fruits of the indeterminate Big Mama paste tomato (Lycopersicon esculentum, 'Big Mama') make it a valuable addition to the canner's garden. This variety matures in 80 days.
Plum Tomatoes in the Garden
Select a location in full sun for tomatoes -- at least six to eight hours a day. This crop is a heavy feeder, so fertile soil and continued fertilization is required. Prepare a space by tilling or digging with a spade and remove all grass and weeds. Work 6-24-24 fertilizer into the top 6 inches of soil when the area is being prepared for tomatoes at a rate of 1 pound per 100 square feet.
Tomatoes like slightly acidic to neutral soil -- 6.5 to 7.0 pH. Use an at-home soil test to measure soil acidity. For soils that are too alkaline, lower the soil pH by 1 point by adding 1.5 pounds of elemental sulfur per 100 square feet. For soils that are too acidic, increase soil pH by 1/2 point by adding 3 pounds of lime per 100 square feet. Work sulfur or lime into the soil the when adding fertilizer, if needed.
Wait until the soil temperature reaches at least 60 degrees Fahrenheit to plant tomatoes. Place smaller determinate plum tomato varieties 24 inches apart and indeterminate varieties at least 36 inches apart in rows 4 to 5 feet apart.
Water tomatoes thoroughly after planting and give them 1 to 2 inches of water a week throughout the growing season.
Fertilize plum tomatoes three times after they are planted: when the first fruits are about one-third grown, again two weeks after the first ripe tomato and once more one month later. Side-dress tomatoes by spreading fertilizer between the rows of tomatoes. Add 5 pounds of 10-10-10 fertilizer per 100 feet of row of tomatoes during each fertilization period. Work the fertilizer into the top inch of soil.
Expect the first harvest of plum tomatoes in 70 to 80 days, depending on the variety.
Harvest tomatoes when they are full red -- or yellow for golden varieties -- and when they are firm but not solid. If tomatoes are soft, they are overripe and should be composted.