Remove weed barrier?

9 years ago

last modified: 9 years ago

I have raised beds for my flowers about 5-6 inches tall. Most were built about 4-6 years (some 1-2 years) ago with weed barrier put on the bottom...then 5-6 inches of soil on top. For the most part, things grow fairly well. However, I have some things (like black/blue salvia, phlox, etc) that just do not grow well from one season to the next. Several perennials I buy don't grow or don't flower or die. Many annuals (candytuft, gilia, vinca, etc) don't hold up or grow as well as they should...they seem stunted. I have done soil tests, and things seem to be pretty ok (pH in range for most suff...little to lot low in a few; K and phosphorus in range or a little high). I never see earthworms.

This year, I planted flowers in a box with 15-18 inches of soil (weed barrier was down below that). EVERYTHING grew like crazy!! I couldn't believe how much taller my zinnias and cosmos were. I still have a vinca growing (they always die after a few months). This box actually had very acidic pH due to the previous hydrangeas (I added lime as directed by soil test)....however, all the plants are much taller than their counterparts in the boxes with 5-6 inches of soil.

The difference could be just b/c the deeper box had some fresh soil put in, but I am seriously thinking the weed barrier may be a big issue. I know now we shouldn't have put it down. Is it a problem even with 5-6 inches of soil on top? I don't think most of my perennial roots (salvia, rudbeckia, Veronica, aster, chrysanthemum, balloon flower, etc) are growing deep enough to touch the fabric (at least, not ones I move...though, I am more likely to move poorly-thriving plants). But...could the weed barrier, even at 5-6 inches deep, be inhibiting good root growth?

I am very willing to dig up my gardens to pull out the fabric (even knowing I may lose some plants). Do you think that is advisable? What should I do for the clay under the fabric...mix it in with compost (I am mixing in some compost with the soil that was above the barrier)? Put down newspaper or cardboard in case I dig up seeds (if anything is even alive under the fabric) or just not put anything down on it since it was smothered already so long?

I know this is long, but I would appreciate some help.

Featured Answer

toxcrusadr

9 years ago

I don't know that it was doing anything for you at 5-6" down anyway. Seeds that sprout actually have to be near or at the surface - where you plant all your seeds. Weeds are no different. If you had tough grasses that would come up through, cardboard or newspaper would have killed that off and then degraded away.

I'd get that stuff out of there, and while you're doing it would be a good time to double dig and add some compost. Don't worry about putting anything else down there. Take your time, one bed at a time, a square yard at a time, fall or spring, whatever works.

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Comments (8)

floral_uk z.8/9 SW UK
9 years ago
5 - 6 inches is simply too shallow a soil depth for most things. Follow tox's recommendations.
TNflowerlover Zone 7a thanked floral_uk z.8/9 SW UK
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gardengal48 (PNW Z8/9)
9 years ago
Agree with tox. Short answer is yes, the weed cloth is very likely hampering good root development. And no, the beds require nothing else at the base to smother grass or weeds or whatever. I also like his suggestion to work in some compost or other organic matter.
TNflowerlover Zone 7a thanked gardengal48 (PNW Z8/9)
TNflowerlover Zone 7a
Original Author
9 years ago
Thank you three! Having 3 people agree so quickly definitely reassures me I am not wasting my efforts. :)

More questions. First, I now have 5-6 inches of garden soil...weed barrier (soon to be removed)...then clay.

I definitely plan on trying to break up some of the clay when I remove the weed barrier. How much compost (%) should I mix in with it? I can get truckloads of compost or leaves (or both--leaning that way) from the city. Will it matter which one? I assume the leaf mulch would leech more nitrogen out of the soil as they break down?

i am thinking it would be good to mix in 10% or so compost into the good soil above the clay? Sadly, my efforts at composting in the past have stunk (no pun intended). I finally getting it going, but it will be a while before I have enough....figure I should take advantage of the truck while I have it. :)
Jean
9 years ago
last modified: 9 years ago
Mix in 20% compost.
TNflowerlover Zone 7a thanked Jean
TNflowerlover Zone 7a
Original Author
9 years ago
Thanks, Jean!
toxcrusadr
9 years ago
last modified: 9 years ago
Compost is better for digging in, leaves are better for mulch IMHO. Both will work both ways to an extent.

If your deeper soil is not as good, add more compost there if you can. If you dig one shovel depth down (below the former weed barrier), add 1-2". I like to turn it over once, add the compost, and redig to break up larger chunks of soil and incorporate the compost. Or you can till. Then add back the surface soil and repeat. If it will be unplanted for awhile - like all winter - leaf mulch would be great on top. Your soil will be so nice you'll want to roll in it like a puppy.
TNflowerlover Zone 7a
Original Author
9 years ago
last modified: 9 years ago
Ahhh I can remember the difference with that simple explanation. :)

Dh has done a decent amount of digging in our *lovely* clay and said that it will take a VERY long time to break apart so much clay into usable pieces (I think it may be "dead", too, since most of it has been under the barrier for 5+ years). Since he is already being super awesome and wants to help dig out the clay (5 cubic yards of it)....I am hoping to purchase either straight compost or a topsoil/compost mixture to mix in with the soil already there (mostly Miracle Gro Garden soil...again, I didn't know what I was doing....whoops). I figure I can still leave/mix in the small chunks of clay, since I hear it does have a lot of nutrients. :)

lol Love the puppy comment! I really am looking forward to good soil....hoping I don't screw it up this time! I really appreciate the help here.