Are garlic and tomatoes prone to the same diseases?

September 16, 2026

“Can you follow tomatoes with garlic safely in the garden?”

Frequent Flyer Lisa in Harleysville PA writes:

“You answered one of my questions for a previous "ask Mike" section of the show. Thank you for that. This is kind of a garlic part 2, in preparation for next year.”

McGrath here: A note to all of our listeners/readers: Lisa gets to roll again right away, because she couldn’t have asked a more timely question right now—and it concerns an issue centered around one of the most important aspects of crop rotation; actually, two of them. The rest of you: send YOUR questions, comments, tips, ticks, etc to YBYG@ptd.net and you too can be a YBYG Frequent Flyer!

Anyway, Lisa sent photos of some very nice-looking raised beds (with big hoops over top and everything!) She identified four of them as A through D, plus a pollinator garden that may or may not be a raised bed. She continues:

“I rotate my tomatoes every couple of years. I grow large indeterminant varieties and they normally provide me with plenty. This year I had my tomatoes growing in beds C and D. I had planned to move them to beds A and B next growing season. Sadly, I got hit pretty hard with disease this year. Honestly, it's been creeping up year after a year, a constant struggle. I totally lost two plants this year. Fortunately, my Sungold cherry tomatoes and Lemon Boys are holding their own and providing me with a low to moderate harvest.”

Interrupting Me here: Cherry tomatoes are invulnerable to everything except Kryptonite and magic. Plus, they grow fast enough to outrun almost any disease in a single bound. Season. I meant to say in a single season. Of course I did. Ahem.

Anyway, I have come to feel that the smaller the fruit, the less disease-sensitive the plant.

Now, thanks to my wonderful farmer friend Melanie DeVault at Pheasant Hill Farm, who provided all my starts this season, I received three surprise plants each of Sungold (which I don’t consider a true cherry tomato) and Lemon Boy, which lived up to its reputation of top-shelf sugary sweetness. Lemon Boy was the most popular tomato I grew this year.

Lisa continues: “I know I'm going to need to solarize all four beds next year. Is it possible to plant my garlic this September, harvest it as usual around June and solarize all four beds after?”

No. It is not practical.

To solarize correctly, you need to weed the beds, level the soil, totally saturate the soil with water, and then stretch two to three mil clear plastic over the beds, down the sides and onto the soil, where you will use bricks to hold the clear plastic tightly in place and let the bed bake for a full season—and this will only work if the garden receives a LOT of full sun that year. It would not have worked this past season, as we had too many cloudy and rainy days. Yes, most of the mid-Atlantic endured record heat waves, but a lot of those were on cloudy days (which helped make the humidity even more unendurable).

And dat’s the truth. Solarization is not what gardeners hope. You can’t throw a tarp or black plastic over a bed for a month and expect to destroy all of the weed seeds and disease organisms in your soil. At best you’ll grow mold on the top of the soil.

Obviously, I don’t recommend solarization as an option here, but if you want to try it, prepare one bed as just described at the start of the season and pray for sun (as opposed to rain, which is the other Gardener’s Prayer). But I think the easier and more practical solution is crop rotation. AND by choosing future tomato varieties that have been shown to be verticillium-resistant. (Indicated by the bold letters VF in descriptions and on the seed packet). Back to Lisa:

“Can I safely plant garlic in a bed where tomatoes struggled with disease? Are they subject to the same diseases?” No—not even close. Tomatoes by their nature are prone to inviting many different diseases in for dinner. Your verticillium wilt—the single most common tamata disease—results when you plant your tomatoes in the same spot year after year.

You probably won’t notice anything the first year you follow tomatoes after tomatoes; maybe some yellow leaves at the base that you’ll pull off because you don’t like looking at them.

But the wilt in the soil is now multiplying fast. The third time you plant in the same spot, yellow leaves will appear early in the season and move rapidly up the vine. If you’re lucky and the plant is a fast-growing indeterminate variety, you might have a section of greenery left at the top. (Luckily, the tomatoes produced on infected plants are perfectly safe to eat.)

Year Four would not be Fantastic. The plants will be dead by July. This is the number one reason for crop rotation in a household garden. If you are aware of this issue and never follow tomatoes with tomatoes, the verticillium without a host plant will quickly die off, and you might get away with a rotation of just a year off—two is definitely safe.

But if you’re just hearing about this now and your tomato plants have endured Year Three or Four, you’re in a world of trouble. That soil has become a highly efficient verticillium factory and it will take three or four years for the wilt to starve to death. (Unless you get lucky with soil solarization, which again, must be done correctly to work.)

Garlic: In my many decades of garlic growing the only disease to pop up has been neck rot, which is caused by a totally different disease organism. Rotating garlic and tomatoes is an excellent idea. And get those garlic cloves in the ground NOW. The old ‘Gardener’s Superstition’ about waiting until November results in weak and undersized bulbs at harvest time.

Lisa concludes: “What month do I have to start the solarizing process? Is there any way to do it now or do I have to give up a tomato season next year? Do I also have to give up next year’s garlic season?”

The answer to the first question is you need to begin the process early in the Spring, when the clear plastic will begin heating up the soil on the first safely sunny day. And obviously, you can’t—and shouldn’t—begin now. It would be a waste of time and you’d have to do it over as the fragile plastic would not survive the winter. Start the process when the soil is safe for cool-weather crops, like lettuce and other greens. Clear the designated bed of any plants or mulch several weeks in advance to begin slowly heating the soil.

But when it comes to your tomato and garlic issue, I don’t think you have to give up either. Hopefully you have at least one bed where you can safely grow the big, beefsteak varieties shown in one of your photos. I recommend growing garlic in one of the previously wilt-infested beds. If its soil has become heavy over time, mix in a lot of perlite to provide better drainage, and then pull any bad looking brownish garlic stalks as soon as they appear throughout the season.

As for the small and tasty tomatoes you seem to love, I would (and will) grow them in containers this coming season. And place those containers at waist level, so you can pick and eat the little sweeties without bending.