How to Stop Blossom End Rot on Potted Tomato

Blossom end rot on tomatoes

keep tomato plants warm

self watering pot

potted tomato plants

mulch kit with self watering pots

luscious red fruit

Why did rotten brown spots suddenly appear on my tomatoes? It was late June in USDA garden zone 4. The disease resistant tomato plants from my local garden center had doubled in size and several tomatoes appeared on the stems. They seemed happy in large pots on my sunny driveway until the rotten brown spots appeared. I had blossom end rot! Here's how to solve the problem.

Purchase disease resistant tomato plants. Your local garden center will help you pick the best quality plants for your USDA gardening zone. This doesn't prevent blossom end rot, but helps prevent bacterial, viral and insect related problems.

Keep your new plants warm. Cool soil and chilly night temperatures are hard on tomatoes. Wait a couple of weeks after the last frost date before planting. In zone 4 tomatoes need to be protected until around June 1. Purchase your plants when there are good selections to choose from and put them outside on sunny days. Bring them indoors at night. consider how warm and humid the greenhouse is compared to the spring weather and really baby young plants.

Self watering pots help prevent blossom end rot. They have a well below the soil pan that holds up to four gallons of water. The plant will draw water as needed during hot dry weather. Lack of soil moisture is the number one reason for blossom end rot.

Plant one plant in each planter. Some companies suggest you can plant two in each pot but that reduces available soil moisture for the roots.

Add time release fertilizer when you plant. Choose a product recommend for tomatoes.

Mulch top to keep the roots cool and slow evaporation of soil moisture. Use shredded paper, straw or purchased mulch like cocoa shells. Paper bio-degrades and doesn't get moldy. Wood chips draw nutrients out of the soil as they decompose but can be used as well.

Uneven watering is the number one reason for blossom end rot. Tomato plants grow extremely fast in the spring and thrive with even soil moisture - not too soggy but never dry. The roots and leaves draw available soil moisture first leaving the baby tomatoes to suffer if the soil gets dry. Scientifically, the cells are damaged when calcium in the soil cannot draw up into the fruit during a period of waterstress. A newly planted tomato plant has a very small root system and needs watering from the top until established. Even a few dry hours promotes blossom end rot.

Remove any blighted tomatoes. Once blossom end rot develops the fruit will rapidly deteriorate. While it doesn't spread, affected fruits are in-edible and you want to direct the plant's energy to setting new fruits. Don't fret, blossom end rot is usually a condition of the first crop because of shallow roots and rapid growth. Once the roots fill the pot there is less risk if you keep your planter watered.

Tips:

Keep an eye on the well, self watering plants cannot walk to the hose to get a drink!

Ask a neighbor to check your plants if you will be away.

Use clean potting soil every year to prevent harboring tomato diseases or pests.

Place your pots in a sunny position with good air circulation.

Keep new plants warm and watered.

Companion plants such as basil, marigold, nasturtium or parsley are compatible with tomatoes, but will compete for space and moisture in a pot.

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