Weed Mat: Is is Necessary?

Hello Everyone!! I'm new the grand world of Square Foot Gardening, and have a question. Is the weed mat underneath the SFG box really necessary? Is its only use to keep out weeds? Because it appears that it would really be useless as weeds wouldn't survive under 6 inches of dirt, correct? Also, is 6 inches of soil enough for the plants roots to survive in, even if the soil is perfect? Because I've read that roots need up to 3 feet of cultivated soil to reach peak growth. What are your thoughts and discoveries?

a weed barrier is a definate thing, yes weeds will grow and thrive even under that amount of soil. plants are know survivers if the roots can't go down they go sideways to find water/food to survive. case in point b/h hada rose of sharon bush in front of the house last spring i dig it up the root "ball" was only 6 inchs deep cause who ever planted it did so on top of a chunk of old concrete 14 inch wide need less ta say the roots grew down, out and around it. hope this helps


boog/mike

Beth.2 wrote:Is the weed mat underneath the SFG box really necessary? Is its only use to keep out weeds? Because it appears that it would really be useless as weeds wouldn't survive under 6 inches of dirt, correct? Also, is 6 inches of soil enough for the plants roots to survive in, even if the soil is perfect? Because I've read that roots need up to 3 feet of cultivated soil to reach peak growth. What are your thoughts and discoveries?

Hi Beth,
Welcome to SFG. To answer your questions...
Yes, the weed barrier is necessary. Weeds and grass are amazingly resilient and don't go away without a fight. For this reason some SFG'ers even dig up the grass before putting in their raised beds. My raised beds are 1' deep and were originally filled with soil (good 'ol dirt), with a weed barrier AND many layers of newspaper underneath. I STILL had bermuda grass making it's way to the top. ARGH!

Yes, 6 inches of soil are enough - especially if the soil is perfect. Mel Bartholomew spent over 15 years perfecting his methods. He's done all the experimenting, trial, error, success and failure so we don't have to. You're life (and your garden) will be so much easier and more successful if you take the plunge and follow the system described in Mel's book "ALL NEW SQUARE FOOT GARDENING." I know it seems counterintuitive in many ways but it does work.

Yes, you will read and hear that gardens need a foot or more of well cultivated soil. That would be true if you were doing a traditional "in-ground" row-type garden. But that's not SFG. (Thank Goodness!). You're not growing in soil. Soil is dirt. SFG doesn't use dirt. SFG uses a customized "growing medium" (called planting mix or potting mix in the stores - as opposed to potting soil which contains dirt). This growing medium (Mel's Mix of 1/3 vermiculite, 1/3 peat moss, & 1/3 blended compost) provides your plant roots with all the nutrients and moisture they need to reach peak growth as sooooo many here on the Forum will happily attest.

Best of luck with your garden. Keep us updated on your progress and please post some photos once it's up and going.

Some kind of weed barrier is needed, but not necessarily the commercial kind. I used 4 layers of cardboard -- it's what I've used for the lasagna layered beds and works as as far as I'm concerned, works as well as commercial weed barrier. NOTHING will keep out Bermuda grass or yucca -- absolutely nothing. Well, except maybe a 6" deep concrete slab.