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Aug 13, 2011 09:26 AM

Do tomatoes hate potatoes?

I'm trying to figure out why the tomato plants in the raised bed in my driveway aren't doing well. The soil is good, I water, the weather here is a bit foggy and cool but not terrible, the other plants I've tucked in the bare spots (lettuce, basil, cilantro) are doing fine, but the tomatoes lack oommph. There *are* a few potatoes that i missed popping up here and there and I vaguely remember reading that tomatoes don't like them. Am I crazy? Could potatoes stunt tomatoes? (I know they're both in the nightshade family.) Oh, and I'm growing several types of tomatoes -- from early girls, to Roma, a couple heirlooms, a cherry.... and they're all growing slowly and producing no more than a couple of fruits at a time.

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  1. A general rule of gardening is not to grow the same family of vegetables in the same place each year. It's called crop rotation. The same family of plants can be grown in the same garden section ...but not in the same section every year. The easiest way to do this is to divide the garden into 4 separate sections and that's where the rotation begins. In your case, just plant those potatoes and tomatoes next time in a place where they have not grown the year before.
    If you could add some composted manure to the tomato plants via top dressing that might help the tomatoes this year...

    Crop rotation prevents disease, controls insects, keeps the nutrients in the soil from depleting, and actually helps maintain the balance of nutrients in other sections.

    4 Replies
    1. re: Gio

      I should know that. I do know that, but I got sloppy because this bed is really the only place that gets a lot of heat and sun. The tomatoes don't appeared diseased, though, just not vigorous. Since the best weather here is in September and into October, I think I'll put a couple new plants in large pots.

      1. re: Glencora

        Oh gosh, I know all about the heat and sun issue. My garden is basically a shade garden both for perennials and vegetables. There's just one spot where I was able to grow all the sun-loving nightshades. I could only rotate them to a secondary, not perfect spot, and planted the hardened off seedlings in a large hole filled with 3 y/o composted manure. It worked, thank goodness. Good luck with your garden!

      2. re: Gio

        One thing about planting them close together is they are both susseptable to the same diseases, like blights so they could cause each other to fail.

        1. re: chocolatejam

          You're right. I wouldn't plant them "close together" but I have planted them in different areas of the same section, plus I practice Companion Planting so nasturtiums, basil, chives go in near tomatoes. Around potatoes I plant bush beans, carrots, peas. Marigolds are good near both vegetables. I also like white geraniums (Pelagonium). They seem to deter all sorts of unwanted bugs especially that brown beetle that loves basil..

      3. I was given a book "Carrots Love Tomatoes" purporting to be the "secrets of companion planting". Some of its contents I regard as myth, but it does say NOT to plant tomatoes near potatoes.

        1. Vaguely off topic (crop rotation is almost certainly it), but it's supposedly possible to graft a tomato plant onto potato roots and get double duty- I know no one who's actually done it.

          1. Both potatoes and tomatoes are heavy, heavy feeders. They're probably competing for nutrients - with the potatoes winning.

            Generally, tomatoes should be given lots of space. It's better to plant less plants and get more from each, rather than more and have them compete. Tomatoes are extremely vigourous plants - their roots can go 10 feet from the plant.

            1 Reply
            1. re: Shazam

              Potatoes and tomatoes are related and have very similar nutritional requirements. This depletes the soil of same type of nutrients, so they essentially starve each other if you don't replenish the soil.

            2. I actually think heat (or lack of) had more do to with my sluggish tomatoes than anything else. They're doing better in September. However, I'm going to stop throwing spouted potatoes in the compost, because they end up growing all over the place.and could spread disease or at the very least use up nutrients meant for other plants. Thanks for all the replies!