My tomato plants are on deck, waiting to be planted, because it hasn’t warmed up to their liking yet. This last week’s nights still dipped into the 30s in my yard, we’ve got more rain this weekend, and a shift to consistently dry and warmer weather isn’t in the forecast.

Which gives me time to choose my planting sites. As I think back, most of my best tomato plants have grown where no tomatoes had grown before: they were growing in new dirt. So this year I’m going to plant many of my tomatoes in new dirt to see if I can’t get many plants that are deep green and bubbling with fruit.

Examples of tomatoes in new dirt

I remember a Sungold cherry tomato plant that I placed between some large rocks. It grew so massive that it was like entering a jungle to pick fruit from the interior.

And I remember a Blue Cream Berries plant (a Wild Boar variety) that I placed at the dripline of a large Valencia orange tree. The plant grew out of the top of its cage, climbed into the canopy of the orange tree, and dripped blue and yellow cherry tomatoes for us endlessly.

So I went searching for photos of those plants but I couldn’t find any!

What I could find were photos of the incremental degradation of my tomato plants when I put them in the same old dirt summer after summer, even after adding ample nutritious compost.

Decent tomatoes in old dirt in 2020.
Struggling tomato plants in old dirt in 2021.

Why did this happen? Why do tomatoes love new dirt?

Why tomatoes love new dirt

It might be that the populations of tomato pests and pathogens are low or non-existent in new dirt. It might be that the nutrients that tomatoes need are abundant in new dirt.

What to do

1. If you have garden space, rotate and rest. Don’t grow tomatoes in the same spots summer after summer. Rather, rotate in crops that are very different from tomatoes.

I’ve found that corn, sunflowers, wheat, and brassicas (cabbage, cauliflower, broccoli, mustard, kale) rotate well with tomatoes, insofar as a spot where a tomato pest or disease is appearing, those crops are unaffected. In contrast, I’ve found that peppers, eggplants, and potatoes do not rotate well with tomatoes, as they share many pests and diseases.

The more time between rotating in a tomato crop, the better.

(More on rotations for tomatoes from the University of California here.)

2. If you are limited on space, be sure to keep fertility high through adding compost and appropriate fertilizers, and do your best to identify any pests or pathogens that are holding your plants back so that you can select the most suitable varieties.

For me, it has been a build up of root-knot nematodes that have prevented some varieties of tomatoes from performing well in my “old dirt” spots. However, varieties that are resistant to RKN still do fine in those spots.

A good plant tag or seed packet should list the disease resistance of a variety.

RKN-resistant varieties, Mountain Fresh Plus and BHN-1021, growing well in the same old dirt in 2022.

3. If you are growing in containers, you don’t need to use a totally new mix each year but you probably should change out some of it. My old neighbor used to grow excellent tomatoes year after year in the same half-wine barrel while just adding about half new mix.

I would incorporate at least some new mix each year (or rotate crops/containers), and be sure to keep the fertility high with compost or fertilizers. And if you don’t like your results, try using all new mix or a different mix. All potting soils are not of equal quality.

(See this post where I compare four mixes.)

New dirt is welcomed by all crops. I’ve grown awesome corn and pumpkins and lettuce and watermelons in new dirt too. But in my experience, tomatoes (and peppers) respond most positively to growing where they haven’t grown before. So in the next couple weeks I’ll definitely be planting some of my tomatoes in dirt that’s never seen a tomato root.

And I might try this hybrid approach that I saw last summer, where a gardener put tomato plants in new dirt (not potting mix) into five-gallon containers and then sunk the containers in the ground wherever convenient. From the looks of the plants, it was obviously working.

He told me the surrounding dirt in that area has nematodes but somehow they don’t affect his tomatoes if he plants this way, even if he grows heirloom varieties that have no resistance.

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