I Want Larger Tomatoes

Q. I have a tomato garden 4x8x1 foot deep. Ever year I put in 3 new plants of early girl, champion, roma.  I redo soil every year and plants get very big with lots of flowers and tomatoes. My problem is tomatoes only get about 2 inches in diameter what am I doing wrong?

Celebrity and Beefmaster from a reader in the Mojave Desert

A. Remember to rotate your tomato family of plants to new locations each year. Try to replant in the same area every five years if possible. Do it AT LEAST every three years to minimize potential disease problems. To learn more about rotating vegetables in the garden go here.

All three varieties of tomatoes are solid producers for the desert. There are several things you can try to get larger fruit. Varieties of tomatoes will have a maximum fruit size dictated by the variety. Heavy crop loads lead toward smaller fruit.

Soil enrichment

Make sure the soil is amended, biologically active and easy to work before planting. A good quality compost goes a long way to improve the soil in all of these regards. When planting, it should be easy to insert a garden trowel into the soil. No digging with a shovel should be necessary after it has been amended.

Fertilizer applications

Fruit size can be affected by fertilizers. Use a pre-planting phosphorus application to the soil at the time of planting. One pre-plant application of phosphorus each growing season should be plenty. Don't forget potassium. Phosphorus is frequently high-end compost but potassium is oftentimes low. Having a little extra potassium in the soil will not cause problems like high amounts of phosphorus can. 

Use light, monthly applications of nitrogen to the soil as a side dressing to boost performance and keep growth at its peak. I like to tell my students, when the soil is giving to the plants, you must give to the soil. When you take from the plants, give something to the plants. Light, continual applications of fertilizer will maximize production.

Bone meal is high in phosphorus

Water

This is a very important limiting factor in fruit size. Smaller fruit are frequently more intensely flavored than larger fruit coming from the same variety. However, we are conditioned to think that bigger is better. If plants are water stressed when the fruit is gaining size, it will result in smaller fruit. This can be good or bad.

Of course soil moisture monitoring is important but what can even be more important is the use of mulch on the soil surface when air temperatures start reaching about 80° F. I don't like straw much because it's hard to work into the soil at the end of the growing season. A light covering, no more than half inch, is all that you need. 

Pine shavings dissolve into the soil quickly and are not a problem when intensely gardening.

I like things you can apply to the surface that dissolve into the soil easier like shredded newspaper, rice hulls, pine shavings used for animal bedding, etc. yes, they can rob the soil of nitrogen but if you're constantly feeding your vegetables it won't make any difference.