Growing Tomatoes

I’ll Meet You in the Garden with Shellie Wise

Tomatoes have two growth habits – determinate and indeterminate.

Determinate varieties are typically your paste tomatoes like Roma or San Marzano, but can include specific beefsteaks. They have a bush-like growth habit that continues until they reach a specific height (usually around 4-5 feet). Once they’ve reached their determined height, all energy is put into producing fruit. All fruit is produced at the same time then their growing season is over.

Indeterminate varieties keep growing, setting new flowers, and bearing fruit indefinitely unless stopped by the gardener or frost. They include many varieties across all types of current, grape, cherry, paste, beefsteak, and heirloom tomatoes. Big Boy, Brandywine, and Cherry Blend are indeterminate as is the paste tomato, Polish Linguisa. They grow very tall and become heavy. They need strong staking to prevent the stems from snapping.

The best way to protect your tomato investment is with good gardening practices.

WATERING: Consistent watering will help with a good harvest. Tomatoes need around 1” per week. Do not overwater as it reduces nutrients and flavor and can cause cracking. Avoid watering the leaves or splashing soil onto the leaves. Using mulch will keep soil moisture levels consistent and aid in keeping the tomato leaves dry.

FERTILIZING: Tomatoes benefit from an application of a balanced 5-10-5 fertilizer a few times throughout the growing season. Avoid using those high in Nitrogen (the first number) as they can encourage excessive leaf formation.

PRUNING/SUCKERING: Pruning tomatoes is a hot topic. There are pros and cons on both sides. Look at the diagram to see where the suckers grow. These side shoots grow in the joint between a leaf branch and the main stem. Those are the parts that you may decide to prune (pinch out). Some gardeners only prune indeterminate varieties and don’t remove all the suckers from a plant. Determinate varieties do benefit from removing all suckers below the first flower cluster as it creates a stronger main stem.

PROS to pruning:

• limits excessive leaf production
• increases airflow within the plant
• reduces the chance of disease & insect damage
• earlier first harvest
• prolongs harvest
• larger fruits
• reduces the total weight of the plant making it easier to maintain
• individual plants can be planted closer together since they take up less room

CONS to pruning:

• fewer leaves can restrict photosynthesis
• fewer leaves can make the plant more susceptible to sunscald
• reduces the amount of fruit

SUPPORT: Tomato plants are heavy! They require sturdy support to keep from falling over, splitting, or snapping off. Cages, stakes, towers, and ladders are all available. Cages supported by bamboo poles, wooden stakes, or rebar provide a lot of support. Pruning your plants will reduce the amount of support needed and make them easier to maintain.

PREVENTING DISEASE: Leaf Spot & Early Blight are two fungal diseases common to tomatoes. Leaf Spot spores live on infected plant debris in the nightshade family – potatoes, tomatoes, eggplants, and weeds like Datura, horsenettle, and black nightshade. They also survive on equipment like pruners, plant cages, and stakes. The fungus appears as numerous brown spots on the leaves. The leaves eventually turn yellow, then brown, and then die.

Early Blight spores live on infected plant debris and in the soil. They appear as irregular dark spots that continue to grow and are surrounded by a yellow ring. Eventually, the entire leaf blackens and dies. The fungus attacks all parts of the plant including the stems and fruit. The fruit eventually rots.

Both appear during warm humid weather and are exacerbated by long periods of rain or poor watering practices. Both begin on lower leaves & stems and spread upward. Both are spread by gardeners, tools, water, wind, and insects. Prevention is key because once your plants have fungus they cannot be cured. Once it takes hold, extra measures are consistently required to prevent the diseases from spreading. All of the garden practices mentioned above help reduce the spread of disease.

• Keep foliage dry. Water the soil and not the plants to keep water and splashing soil off the leaves.

• Improve air circulation by staking/caging and pruning out excessive leaf growth. You want the sun and wind to dry the foliage quickly after rain.

• Follow proper spacing guidelines to increase airflow between plants. Avoid putting plants too close together.

• Use mulch at the base of tomato plants. It limits soil and fungal spores from splashing up onto the plants and helps maintain soil temperature and moisture.

• Rotate your crops each year as the fungal spores overwinter in the soil.

• After using, wipe down your hands and pruners with alcohol-soaked wipes to limit the spread of the disease from one tomato plant to another.

Last updated November 9, 2021