Friday, April 12, 2013

The Secrets of a good Raised, Covered Bed

As I start to plan retirement from intensive Market Gardening, (NEVER from gardening :-) ), I want to pass on a few "trade secrets" learned by experience and experimentation. :-) As we finally move back into early spring here in Montana, getting our 4' wide, 48'long, 18" tall raised bed up and running is one of the first projects on the longggg outdoor todo list.

After reading "Square Foot Gardening" about the same time I needed Physical Therapy following a 1000 pint hand-picked strawberry season in our Market Garden (OUCH!), I was VERY interested in both getting those strawberries up off the ground ;-D, and getting rid of the intensive, on the knees, weeding process needed twice through every spring when one raises perennials without chemical use.

I found easy to follow plans for building raised beds here: . We made our first raised bed 18" tall, and made the corner posts longer, of course. Since the beds are first made upside down... we did that on our relatively flat gravel driveway near the final bed site. We used mostly used redwood from someone's deck remodeling... stain almost completely worn off and placed to face the outside of the bed. Since most of the boards were 12' long 2X6's, we built 4 units... planning for joining the middle sections... with braces, as shown, at the 6' mark of each board. Purchased 4X4 redwood posts were cut such that they went 6" into the ground when placed upright. They were cut 18" even for the 6' mark bracing spots. 3.5" and 4" decking screws were used to attach all the pieces of wood together.

After each section was moved into place and leveled onsite... they were attached to one another to make one long 48" bed. This bed has been in use for 2 years now, and is very solid.

Then hardware cloth (similar to chicken wire but thicker) was placed on the bottom of each bed to help prevent rodents from tunneling.

WHAT WE'D DO DIFFERENTLY >> Grass and Field Bindweed became an issue EVEN through 18" of soil! We had tilled the soil around and under the bed several times prior to installing the bed, but as you can see in the picture... they renewed before we could finish the bed. We eventually laid down landscape fabric on both sides of the bed, and covered it with natural pine chips. Now I would do that AS the bed is established.

In Montana's short growing season, we need to capture all the early and late heat possible. I found 3/4" outdoor PVC conduit (the grey hoops) that would fit inside 1" PVC piping cut into 12" pieces. We found conduit clamps (inexpensive) to attach the PVC footlong pieces inside the beds... even with the top of the beds. 1.25" decking screws were used. Two hoops were placed in each 6' bed section, as shown in the picture. Once you get your covering cloth, you can slip the pipes back out and cut them to the length needed... or measure ahead of time. More on covers later. But keep the hoops IN while you fill the bed with soil, or the insert holes may plug up.

Basic bed done!!

"Square Foot Gardening" recommends a fill of 1/3 peat moss, 1/3 mixture of different composts, and 1/3 vermiculite. Ex.pen.sive for such a big bed! We had locally dug coarse sand-gravel delivered to our gardens. Without a tractor here, and no other innovative idea cropping up, I moved bucket after bucket of the sand mix into the bed by hand ;-}. Great heavy lifting exercise! So the first 10-11" of the 18" bed is straight sand-gravel mix. Then I used a small tarp, laid over each 6' section, and filled the tarp with 1/3 peat moss, 1/6 OMRI approved compost, 1/6 our own llama/mini horse compost, 1/6 vermiculite, and 1/6 the same sand-gravel mix. Shaking the ends of the tarp helped mix the recipe. Sliding the tarp out dumped it into the bed. This was repeated until all of the bed sections were filled to within 1-2" of the top of the bed.

WHAT WE'D DO DIFFERENTLY >> We have good loamy soil. Weed seeds were a concern, but the soil texture is good. We will be making OUR raised bed soil mix 1/2 our own soil from now on... with the other half consisting of the same recipe as above. Why? Besides less expense, the recipe used above dried out too quickly in our low humidity. And a little blew away each time :-O in strong winds whenever covers were not on and plants weren't anchoring the soil mix. Otherwise... all plants grew beautifully in this recipe :-).

STILL IN THE EXPERIMENT PHASE: We were so impressed with the production, and the better use of MY back with the raised bed, LOL, we built 2 more. One is 12" tall, and the other is 6" tall. 12" may be the "right" size? The 6" bed allows watermelon and pumpkins to drape off the side easily :-), BUT it also filled up with our pine wood chip mulch every big wind :-(. The mulch is not blowing into the 12" or 18" beds. So for that reason... we'll be raising the height of the 6" bed as soon as we locate more redwood 2X6's in need of a new use.

Info on covers, watering and plantings to come in future posts. Happy Gardening!!

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