Clay soil; not many leaves, blossoms, or fruit on tomato plants

by June
(Spanish Fork, Utah, USA)

Q. I planted my tomatoes sometime ago. I have 12 plants. Three are growing and have leaves and blossoms. I had little green tomatoes almost as soon as I planted my tomatoes. They grew for awhile but now are not growing, have few leaves, blossoms, or fruit. They look like they are half dead. We have had a lot of rain this year. However, our soil is heavy clay soil here in Utah. We worked in new topsoil in the spring. What can I do?

A. Tomatoes can be grown successfully in clay soil. But clay has two characteristics working against it to produce healthy tomato plants:

1. Compaction. Clay tends to hold water. Retention prevents the water and nutrients from moving through the soil.
   
2. Alkalinity. Clay soil tends to be alkaline, not acidic (alkaline soil has a pH over 7.0). One reason is that clay retains water which prohibits nutrients from leaching away. Tomatoes are best grown in slightly acidic soil with an optimum pH between 6.5 and 7.0. So alkaline soil will not lend itself to healthy tomatoes.
   

Take these options to grow a successful tomato crop when you have clay soil.

• Grow tomatoes in raised beds with open bottoms. This is by far the best recommendation for those gardeners with heavy clay. Fill the raised bed with a healthy combination of compost, top soil, peat, manure, and bone meal. Tomatoes have large root systems and will use the space below the raised bed. With open bottoms, the organic matter and its nutrients will eventually seep downward and amend the soil. The raised bed will give tomatoes a chance.
  
• Grow tomatoes in containers. Tomatoes in pots are most productive in a soil-less medium.
  
• Test your garden soil. Check different nutrients. Also use a simple pH test to test the soil's pH. Determine its acidity or alkalinity. Amend appropriately. To lower your soil’s pH, work sulfur into the soil. To raise your soil’s pH, work lime into the soil. An appropriate pH is an important component to preparing the soil for planting tomatoes.
  
• When planting tomatoes in the garden, vigorously amend the soil in each hole you prepare for each tomato plant. As the saying goes, "Dig a twenty-dollar hole for a two-dollar plant." Then add a generous scoop each of compost, manure, and wood ashes to each hole. Work them in well and add water before planting.
  
• Or, drastically amend your tomato patch's soil each spring with a significant amount of compost, peat, and/or manure to prevent compaction.
  
• Make sure your plants are on a systematic watering and fertilizing schedule.
  

Here is some excellent information about preparing your soil for tomatoes in the home garden.

With some intentionality, you can grow delicious, healthy tomatoes in clay soil. Stick with it!

Good Luck and Happy Gardening!
Your friends at Tomato Dirt