Monday, November 11, 2013

Lost in the Food Forest: rampant growth in Portland

I sent this email years ago to the Portland Permaculture Guild, offering some tips and discoveries from our experiments with dense interplantings in zones 1 and 2:

In zone 1 we have a pretty easy time keeping growth balanced as part of the once or twice daily gathering of greens for salad and omelets, plus occasional dedicated large-scale whack-backs.

Prune/whack ruthlessly where needed. Leave in place as mulch wherever you can.

Designate your paths, at least 2' for main access routes, at least 1.5' for keyhole paths. The plants will invade the paths no matter what, so don't be afraid to make the paths "too big"; you can decrease the frequency and/or severity of your whack-backs if you find you don't mind the plants taking up some of the path. If you make the paths too small you'll guarantee an unpleasant walk through the garden and/or increased maintenance.

Place plants far enough from the paths that they don't interfere.  It can be difficult to determine spacing for perennial veggies based on book data alone; we find that tall plants may fall over into the path after summer rains since they haven't grown up accustomed to the weight of water. I used to want to plant a 3' wide plant (based on book data) exactly 1.5' back from the path to maximize the plant packing. But I now think you need to give a large buffer - maybe 2.5' from the path, and fill in the gap between the large plant and the path with a low-growing plant. You can easily trample the low-grower if it exceeds its allotted space. This makes for easier harvesting anyway--you can reach the large plant in the middle of the bed, and the small plant(s) at the edges.

It's OK to plant the plants more closely together inside the bed--they'll work things out if they crowd or fall onto each other. So I would place two plants with expected 3' maximum width 3' apart from each other. Dedicated trample-tolerant very low-growing ground covers help delineate the path, keep bed plants from spreading into the path, and can fix nitrogen, accumulate nutrients, etc. We're having good success with:
  • prostrate bird's food trefoil (Lotus corniculatus plena)
  • "Treneague" variety chamomile (Chamaemelum nobile)
  • what I think is dutch white clover (Trifolium repens)
  • Pacific silverweed (Potentilla anserina)
Those cute little squash volunteers that look so harmless in late spring will take over 6' or more in every direction if you let them grow. Don't, unless you're really OK with it. Similarly, be realistic that squashes you deliberately plant will want lots of space.

Give climbing plants something to climb, or be aware that they will sprawl across the ground. Tomatoes, squashes, beans/peas/groundnuts/hog peanuts, and mashua will all sprawl if they don't find vertical supports. Some of them will sprawl anyway, and require deliberate guidance to minimize horizontal spread.

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