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Raised Bed Gardening

tree rootsIf you're thinking about building raised beds for your vegetable garden, definitely go for it. Plants do better in deep soil and as long as you don't walk in the beds, you'll also avoid soil compaction. Now what root wouldn't want to grow in nice loose, deep soil? If I was a root, I'd tell all my root friends, "Hey come on guys, nice deep, loose soil over here, let's go!"

But this weekend, I had my first bad experience with raised beds. You see there was a root invasion from trees that were pretty far away. The closest trees to my vegetable garden are at least 30 feet away but I guess that's just a short hop for tree roots. It's almost as if one of these roots said to all his buddies, "Hey come on guys, nice deep, loose soil over here, let's go!"

So on Sunday, I was planning on planting some more salad greens but wound up spending the afternoon digging and pulling roots out of my beds. I always wondered why Mel Bartholomew in the book Square Foot Gardening advised to build a bottom to raised beds. At the time, I was like, why build a bottom, what is this guy crazy? I want earth worms to tunnel up from underneath my garden beds and munch on all that compost that I loaded in there. More like Square Foot Craziness, no bottoms on my raised beds.

Well, I was wrong about that. After pulling a few giant piles worth of roots out yesterday, I made an executive decision. Whenever I build a new bed, a bottom will be a mandatory feature. I don't think I'll use a sheet of plywood for the floor as suggested in the book, but at a minimum, I'll load the bottom up with landscape fabric. Usually, I'd layer newspapers to stop weeds and because I know they'll break down and feed those earthworms that I was talking about. But since I want to avoid future root invasions, I think I'll pass on the newspapers. Do they make landscape fabric out of steel?

Mr. Bartholomew, sir, I'm sorry about the Square Foot Craziness remark. You were right and I should have listened. It won't happen again.

16 Comments:

  1. phyllis said...
    We line dhte bottom of our hardware cloth, primarily the keep crittrs out, and it never occured to us that tree roots may invade, so we'll have to keep an eye on that. The sides are built from Trex (the deck material).
    Kelly said...
    I had the same experience this year. How old are your beds? Mine are about 2 and a half years old and are in the vicinity of a couple of very tall pecan trees. I'm hoping digging them out every couple of years will keep things going, although the roots may come back faster now.

    My friend had a similar situation with pecan trees and added a couple of inches of gravel and landscape cloth to the bottoms of his, yet the roots came back anyway. This scares me.
    PlantingOaks said...
    30 feet, eh?
    I'll have to measure how far my trees are when I get home. They certainly look a long way away.
    Anthony said...
    Phyllis,
    Beds made from Trex sound really nice. I built part of my kid's swing/slide set with Trex and I love the stuff.

    Kelly,
    I read your post and we're definitely going through the same thing. I also concluded that this root digging would become a regular chore that needs to be done every year or two. Let's compare notes throughout the season.

    Plantingoaks,
    Yes, I'm amazed at how far the roots can travel.
    Ki said...
    I did a french raised bed garden one year at the township pea patch. It was the most productive garden I ever had despite lack of water. We had so many tomatoes I couldn't give them away. It seemed like every square inch produced something. Tried it again at our new home but the deer and rabbits were too much to deal with...unfortunately.
    Anonymous said...
    I've used scraps of weed barrier and black plastic to deter maple roots, which love cushy beds. They will take it over end to end! I pull up the plastic or whatever up and replace it once a year, between deep diggings.
    hw said...
    Oh my. That sounds like a lot of work. But, you've got to love how what starts out as a small gardening chore somehow manages to consume your whole day...
    Anonymous said...
    I couldn't have read this post yesterday. I just built and filled my first square foot garden bed last night. And I too, thought, why have a bottom. The deeper the better, right, and there were lots of earthworms when I pulled up the grass so I too wanted to keep them.

    I guess I'll plan on putting in a bottom for next year.
    Karen @ Wiggly Wigglers said...
    Thanks for the great tip. I am just in the process of building raised beds.
    rcmullins said...
    A tip I picked up from somewhere and have been using it, and it works awesome is to lay down a layer of thick cardboard. It lasts for an entire season, enough to kill anything underneath it. Eventually it rots and the earthworms eat their way through into your compost.

    It is called a 'kill mulch'. A layer of cardboard, chunks of wheat straw from a wheat straw bale, then load in your compost and wet it down really well. Wait a week, add a layer of green stuff(about two inches), then more compost on top of it, wet it down again. The heat from the decomposing green, will flat out cook everything underneath it.
    sastian said...
    we lined the bottom of our raised beds with 2-3 inches of gravel with chicken wire below that to prevent them from settling into the ground. the idea is to keep water form leaching up.
    Anonymous said...
    After reading this blog, and having a maple tree near my new garden/bed area (terribly invasive root system!), I decided to try something not mentioned here. Instead of landscape fabric in the bottoms of my 7 beds, I used septic drainbed filter fabric. (.14 a linear foot...4' wide...seems to be fibreglass) I double layered it, stapling it to the bottoms. Over that I double layered chicken wire, making sure no holes were bigger than 1/2"...I have moles! (Hardware cloth was too expensive for me) I'm hoping the filter cloth & wire will last a number of years. When these eventually fail, I may try a perimeter barrier around the garden...perhaps bury pieces of vinyl siding...an idea from another blog.
    davcun1 said...
    I have a major problem with roots from a poplar tree. My beds are about ten feet from the drip line. My beds are: double dug; 2 runs high of landscape timbers; amended soil fill. But the roots are terrible by the end of the season. I end up having to shovel the soil to an adjacent bed; then dig and till down deep to break up the roots. Any ideas appreciated!
    Anthony said...
    Hi davcun1,
    My advice is to either continue doing what you're doing and digging the roots out or put a bottom on the raised bed.
    davcun1 said...
    Thx Anthony,

    I'm thinking of using the 'septic' or landscape fabric on the bottom. Then, I'll try to find some left-over or trashed vinyl siding to line the sides. It's a pretty big job digging out all that dirt and then moving it all back. I have two 4x20 beds. I'd like to go down only a foot; line the beds; then build the above ground sides up higher....but lumber/trex is pretty expensive. Thx again.
    davcun1 said...
    Ki,
    Would you expound on the 'french raised bed'? thx!

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