Articles by Jim Gainan

As published in the Billings Gazette

Proper care of your tomato plants yields bumper crop!

July 21, 2013 12:00 am

Our Garden Center tells me that they have been getting questions on tomato care and problems, so here is a brief summary on caring for one of the most popular plants grown by the home gardener.

Watering and Cultivation

Consistent watering is absolutely key with tomatoes once they are producing fruit. Tomatoes have a relatively shallow spreading root system, so you need to water a wide area around your plants as well as the immediate area to ensure that the entire root system is getting water.

A good layer of mulch spread around the plant will help keep the soil evenly moist and reduce the amount of water lost through evaporation. It will also help to control weeds, minimizing the need for cultivation that could damage the roots of the plant. Root damage could cause wilting, poor fruit set, small fruit and blossom-end rot.


Tomatoes need to be fertilized throughout the growing season. An application of fertilizer at the time of planting should be enough to feed the plants until they begin to set fruit. At this time, apply an additional fertilizer, such as a 5-10-5, monthly or according to package directions. When the tomatoes begin to mature, stop fertilizing.

Common Problems

Problem: Little or no fruit development on a vigorous plant

Possible Causes: Inadequate water; inadequate sunlight; inadequate number of pollinating insects; feeding with a high nitrogen fertilizer

Solutions: Monitor the amount of water being given to plants and the moisture of the soil. Try using a pollination aid such as a blossom set spray to encourage fruit set. It may be too late this season, but think about planting companion plants that attract bees. Use a fertilizer that has a low nitrogen to phosphorus ratio -- like the 5-10-5 recommended above.

Problem: Growth cracks -- cracks in the fruit often radiating from the stem end and possibly encircling the fruit

Cause: Extremely rapid fruit growth which may be brought on by abundant rain or irrigation after a period of drought and high temperatures

Solutions: Monitor the amount of water and apply a layer of mulch around the roots of the plant to help retain moisture.

Problem: Blossom-end rot -- brown/gray/black leathery rotten spot on the blossom end of the tomato

Possible Causes: Calcium deficiency in the plant due to fluctuations in soil moisture; heavy applications of high nitrogen fertilizer; root damage

Solutions: Monitor the level of moisture in the soil and apply a layer of mulch around the roots of the plant to help retain moisture. Avoid root damage by not cultivating within a foot of the base of the plant.

Problem: Sunscald -- pale yellow to white spot on the side of the fruit facing the sun

Cause: Fruit is over-exposed to the sun due to lack of leaf cover -- whether leaves have been damaged due to disease or insects or even us if we over-prune the plant

Solution: Be observant and proactive when it comes to defoliating insects and disease. Do not over-prune the plant. Shade the plant to reduce the exposure to the sun.

Problem: Catface -- misshapen fruit with scars and holes in the blossom end

Possible Causes: Cold temperatures when in blossom; applications of high nitrogen fertilizer; uneven watering; exposure to an insecticide/herbicide

Solution: Avoid setting transplants out too early in the season or use protection when cold temperatures are expected. Maintain even soil moisture and apply a layer of mulch to help retain moisture. Be cautious if applying insecticides and/or herbicides in the area around tomatoes.

Jim Gainan is President of Gainan's Flowers and Garden Center in Billings.