Hi Patty,

It is exactly for the reasons you mentioned---both the depletion of nutrients from the soil and the accumulation of both diseases and pests in the soil and surrounding area.

While it would be nice to be able to rotate tomatoes to a brand new area annually on 3 or 4-year rotations, this is not easy for a home gardener to do, particularly if you also grow lots of other vegetables and/or flowers that are in the Solanum family (potato, pepper, eggplant, tomatillo, ground cherry, garden huckleberry, and the ornamental nightshades).

If rotating nightshade family plants to a new area where plants in that family were not grown the year before isn't possible, you can add a lot of compost and other organic matter to your soil every year to prevent nutrient depletion from giving your progressively weaker plants and poorer crops every year. This will work well and, as long as you can keep the soil healthy, it also will help prevent a serious build-up of soil-borne diseases in the soil. When you grow in the same soil every year, mulching heavily beginning when the plants are young and small is especially important because it can help prevent soilborne diseases from bring carried up onto the plant foliage by soil splash when it rains or if you use overhead irrigation.

Unfortunately, you may find that, in the absence of crop rotation, you do see a build-up of pests in a specific area because they have learned that the plants they like grow there. To help lessen that, it is important to remove all crop residue at the end of the season and either compost it or bag it up and have it carted off in the garbage. Then, if you will turn over the soil in the area in the winter a couple of times (either by hand or using a small rototiller or cultivator--I use my Mantis cultivator for this) during very cold weather, you will be exposing insects that overwinter in the soil to cold temperatures that kill them. I try to do this one time each in December, January and February, but in order for that to work, I cannot plant fall garden plants like kale, spinach or lettuce in those areas because they often survive the whole winter. Or, if I plant those plants there, I have to sacrifice them by removing them in December so I can work the soil.

Since we have chickens, I like to let the chickens go into the garden where they will dig and scratch their way through the freshly overturned soil, eating insects and even weed seeds as they go.

I have raised tomatoes, peppers, potatoes, and sometimes eggplants, in the same soil for 15 years without much crop rotation. Other than early blight, which is only bad in my garden in wet years, I generally don't have disease problems. I don't know that I can blame early blight on the lack of rotation either, because even when I put tomato plants in brand new soil-less mix and grow them far away from the veggie garden, they eventually get early blight too, though maybe a month or 6 weeks later than the plants in the big garden. If only I could grow all of them under a roof where rain never fell on their foliage, then they might never have early blight at all!

So, if you can't rotate plants in the nightshade family, I think that working to keep the soil healthy and to keep the pest levels low pays off.

This year, we built a new garden out back, and it is probably 300' from the front garden, or maybe a little farther away (I really should measure it and see). I planted leftover tomato plants there in early May as a test to see if those plants would stay healthier in 'virgin' soil than plants in soil where tomatoes had been grown for 15 years. Did they? Well, it likely isn't a fair test because native solanums (like Carolina horsenettle, but also some others) had grown there in that pasture for at least the whole time we've lived here and I know I have seen early blight on some of those plants in wet years, but the tomato plants out back didn't show any early blight until late July. If we'd had a drier summer instead of a rainier one, they might not have had it at all. The plants in the front garden had some minor early blight show up as early as latest May or earliest June, after two weeks of nonstop rain. It didn't kill the plants, but they haven't looked as good since then as they did before that. Still, they've produced more fruit than we can eat, so I don't fret about early blight too much. I remove the diseased leaves when I have time, and otherwise just pretty much ignore it. Once we're back to our usual hot and dry weather, the early blight doesn't advance too much.

The kind of diseases that exist in soil and which affect tomato plants that would worry me would be something like fusarium wilt, for example, or southern blight. The fungal diseases and bacterial diseases are something that you can fight if they show up, or you can prevent the fungal diseases for the most part by spraying your plants regularly with chlorothalonil regularly from the very first week they go into the ground. I don't use chlorothalonil because I prefer to grow organically, but if I had to use it in order to be able to raise home-grown tomatoes, I'd use it. We usually are so hot and dry down here about 7 or 8 years out of 10 that the fungal diseases aren't a huge issue most years because it is fairly easy to keep water off the plant foliage by using drip irrigation. You live in an area with a lot more rain most years, and a lot higher humidity too, so you might find it harder to prevent disease without the use of Daconil or something similar. Or, it might never hit your garden and be a problem for you. When I see early blight appearing on the native nightshades in our pasture, I always know then that it is about to appear in my garden. If you don't have native plants that harbor early blight in pastures around you, it might not be much of an issue for you. When I lived in Fort Worth in an old and well-established neighborhood with no 'wild' areas nearby, early blight was rarely an issue and I grew my tomato plants in exactly the same spot every year because it was the only full sun area in an otherwise extremely shady yard.

If you notice an increasing problem with fusarium wilt, that would be a sign you really need to not grow tomatoes in that area for a year or two in order to try to get that disease out of your soil.

The bacterial diseases common to tomato plants, like bacterial spot and bacterial speck, are only a problem for me in the rainiest of years and I generally just don't even worry about them at all. If they are an issue for you in your rainier and more humid climate, mulching would be the main way to try to prevent them, and then if they appear on your plants, you could use something like a copper spray to treat the plants in order to stop the bacterial diseases in their tracks.

So, since crop rotation is not easy to achieve in a home garden, just do what you can to address keeping the soil nutritious and focus on disease prevention or on treating them when they appear.

If you notice that your plants start having lots of disease issues and that treating them doesn't help, then you might have to move the tomatoes someplace else for a year or two in order to break the cycle of disease. You could do that, for instance, by growing tomatoes in large containers or grow bags. You might never have a disease build-up in the soil and might never have to rotate your plants out of your garden in order to address it.

One way to help keep soil-borne diseases from getting out of control in soil where rotation cannot be done is to solarize your soil under plastic, preferably in the hot summer months. The heat under the plastic can get hot enough to kill the disease organisms. I've only solarized my soil once---in the beginning when we moved here and don't find it necessary to do it here.

This year I am growing lots of ground cherries and garden huckleberries in addition to the usual tomatoes, peppers and potatoes, so have more nightshade plants than ever before. I only have one small garden area (the corn cage area where I grow corn because it has a fence that keeps the raccoons out) where I've never grown nightshade plants at all. I'm toying with the idea of growing tomatoes in the corn cage next year in order to give the soil a break, but I can't fit all the peppers, potatoes, ground cherries and garden huckleberries into the corn cage area too, so my garden won't exactly be free of nightshades.

If it was essential for a home gardener to rotate the nightshade crops, I'd be in trouble, and so would a lot of other home gardeners.

Hope this helps,

Dawn

Thank you, Dawn. I've been able to move them just a little bit every year so far but I surrendered to the evil Bermuda grass in one area now so it is not available anymore. I appreciate you giving so much information. I'm going to put a lot of compost in this fall. We'll see what happens next year.

Patty, You're welcome. You know, I have been thinking about this issue a lot. My dad's garden wasn't all that big until after we kids grew up and left home because he had to share the back yard with 4 kids, a dog and a cat. He never rotated his tomato plants, and I don't necessarily remember him having a lot of disease issues. He would have septoria leaf spot in a wet year, and spider mites in July and August of every year, but even after he switched to growing them in whiskey half-barrels so he could grow more corn, potatoes and onions in the ground, he didn't rotate. He just added a little new soil-less mix to his barrels every spring. He never dumped out all the mix and started fresh.

I think if someone has fusarium wilt or bacterial wilt in their soil, then rotating becomes essential.

I hate the evil Bermuda grass. I think I've done a pretty good job of controlling it better this year, but it always creeps in at all 4 corners of my big garden plot. I've also done a somewhat better job with controlling the Johnson grass, but Dallisgrass is driving me up the wall. I guess it always is something.

Dawn