Shop Products
Houzz Logo Print
haask

Tomatoes Red Oak Juglone Raised Beds HELP

haask
10 years ago

I have a vegetable garden south of a HUGE red oak. After years of great yields, the plants closest to the red oak began to die. I finally figured out that it was juglone poisoning. (Think Black Walnut). Without getting into too much detail, there's no doubt about the cause of my plants demise.

Since Red Oaks give off much less juglone than Black Walnuts, I decided to try to live with the situation. Last year I used a post hole digger to dig down and sever the small roots in the hole, backfilled the hole with rich soil, then planted in the backfilled holes. IT WORKED! This technique resulted in zero plants lost throughout the season. So this little experiment tells me that it is possible to grow vegetables near the Oak by simply separating the roots from each other.

Fast forward to this year. I would like to switch to raised beds on the part of the garden closest to the red oak. I would like to set the raised beds on landscape fabric to keep the Oak's roots from coming into contact with my vegetables. My raised beds will be 24 inches high, and sit directly on the landscape fabric.

My questions are: Does anyone see a better solution to the problem (besides cutting down my neighbor's 100 foot oak)? Will a 24 inch high raised bed be OK for tomatoes? Will the landscape fabric allow proper draining if the bed just sits on top of it?

Thanks!

Comments (13)

  • digdirt2
    10 years ago

    I don't think there is any doubt that the landscape fabric will slow your drainage. That could be a good thing but it means you will have to monitor your moisture levels more carefully.

    But over time that landscape fabric will degrade no matter the quality to begin with. As that happens the tree roots will invade the bed. Indeed some invasion happens even while it is fresh.

    They are drawn to the moisture and the easy to permeate soil consistency. How long it will buy you I can't say but it won't be a long term solution. Only moving the bed to another location can accomplish that but you might also consider using hardware cloth instead of the landscape fabric for better drainage and longer lasting effects..

    And the depth isn't going to make much difference IMO - 18" is as good as 24". The allelopathic effect**, once in the soil, is in the soil.

    That said, living and gardening surrounded by an oak forest (both red and white as well as hickory) as I do I find that growth suppression is more a result of the leaves rather than the roots with these particular species and an annual deep tilling eliminates the majority of the problems caused by the roots. So be sure to eliminate all the leaves from the tree in the garden.

    There is also some testing evidence that only certain types of plants - primarily monocots - are affected by the red oak coumarin. So in some part a different plant layout may help.

    Just some thoughts to consider.

    Dave

  • glib
    10 years ago

    This would be a first for red oak. Anyway, when it comes to surface roots they are well behaved trees, but that only means that you will have roots coming from farther down into your beds.

    For a number of years I managed maple roots (which are fairly shallow) by digging along the perimeter and severing the roots. That worked out OK, and was needed only every second winter.

    If you really think it is juglone, try planting come beans, chard and squash. They will be affected a lot less than tomatoes. If you get in a situation where the squash is alive and the tomatoes dead, that would be it. Note the squash plant will be smaller than usual, but alive. I have a large BW close to my house and I have a lot of experience. Tomatoes and potatoes get zapped (solanaceae really) but most other vegetables survive although they do not grow as well.

  • haask
    Original Author
    10 years ago

    glib,

    Thanks for your response. Anyway, I've researched it, and found out that Red Oaks do produce juglone. Also, the juglone-resistant plants have no issues nearer the tree. They thrive. It's just my tomatoes and cucumbers that suffer.

    Ken

  • digdirt2
    10 years ago

    This would be a first for red oak.

    Sorry glib but the phenolic coumarins from Red Oaks is pretty well established. It supposedly isn't as strong or as fast acting as juglone but still allelopathic, especially the leaves and bark.

    Dave

  • Ohiofem 6a/5b Southwest Ohio
    10 years ago

    I have a small yard surrounded by several old black walnuts, so I grow most of my vegetables in containers. We use a mulching mower to mulch leaves onto the yard in the fall, and I always kept them out of my compost pile. One year my husband, trying to be helpful, raked the whole yard in early spring, and put the material on top of my compost pile unbeknownst to me. When I added a small amount of that compost to my container mix, I had several tomato plants that were stunted or even collapsed after a month or so in the containers. It was only after the fact that I figured out what happened. After that I learned to take great care to keep any material from the trees out of my compost.

  • glib
    10 years ago

    The dose makes the poison. 90% of my compost is red oak leaves, and in particular tomatoes get mulched with that. Red oak should have more than a factor of ten less juglone than black walnut.

  • seysonn
    10 years ago

    I have a personal experience with Black Walnut.
    Juglone from BW contaminates the soils just under the canopy and as far as the roots spread. Contamination from the leaves, bark, rain wash will last in soil for a long time.

    Another thing:
    NOT every plant will be affected by juglone. Of all the things that I grew , only tomatoes died. Nothing happened to peppers, okra, cucumber, shiso, bean, gourd ...MAYBE they did not do very well, but they survived.

  • planatus
    10 years ago

    Even with a weed barrier at the bottom of your raised beds, roots will find their way in over time. The first year will be fine, the second year you will see some roots, and in the third year (or maybe fourth) year you will want to renovate the beds and put down a new barrier. Many people use old carpeting for this. You also can make a moat around the outside edges of the beds of some material that's easy to slice through, like sawdust or shredded hardwood mulch. Between crops, use a sharp spade to go around the beds and sever roots tickling at the bottom of the beds to buy some time.

  • lucillle
    10 years ago

    Haask,
    This year I planted half my tomatoes and some other veggies as well in very large pots I forget if they are 20 or 25 gallon but they are pretty big, and the other half in raised beds.
    I don't know how large your garden is but since I'm thinking the juglone gets worse as time goes on what with years of leaves under the tree, you might experiment with a few containers. I bought 10 of the giant pots for pretty reasonable and it looks like they should last for years.

  • digdirt2
    10 years ago

    The dose makes the poison. 90% of my compost is red oak leaves,

    glib - I think the composting first is bound to make a big difference. Plus the red oaks issue is coumarins (phenyls) rather than juglone and they supposedly dissipate faster, especially with composting.

    Dave

  • haask
    Original Author
    10 years ago

    Thanks everyone for the information. I find it interesting that you hardly hear of the problems associated with Red Oaks. It's always Black Walnuts that you hear about. Anyway, all the leaves are raked out of the garden after the fall, so I'm not worried too much about the leaves.

    It's an interesting chain of events when I plant tomatoes nearer the tree. They start off great. Grow for about a month or more. Then all of a sudden (usually after a hard rain), they wilt and die in about a day.

    I scratched my head for years. I planted juglone tolerant plants, and whoa-la! Problem solved. However, I really do need to rotate in plants that are not tolerant.

    Thanks again.

  • lucillle
    10 years ago

    Haask since you seem to be well read on the subject, what is your opinion about the allopathic qualities of other types of oak trees?

  • haask
    Original Author
    10 years ago

    I live on an acre with about 25 red and white oak trees (and many other species). In my situation, I have very little choice as to where I place the garden. The closest point of the garden is around 20 feet south of the Red Oak. The Oak is so tall, that the garden is in full sun all day long.

    My opinion on the Red Oak is that it is seems much less potent than a black walnut. The garden can be managed, by simply keeping the roots away from the vegetable plants.

    That's basically my experience. I have no other experience with any other types of oaks. From my research, I'm not sure if I even remember any other oak being an issue.

Sponsored
Virginia Kitchen & Bath
Average rating: 4.9 out of 5 stars151 Reviews
Virginia's Award Winning One Stop Kitchen & Bath Remodeling Resource