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Rise to the next level of gardening Byelevating your growing beds
Question. Dear Mike: We're going toplant our first garden this spring. Because of the poor, rocky qualityof our soil we're going to put in raised beds (It's either that orblast with dynamite every time we want to plant radishes!) I alreadyknow not to use pressure-treated wood, but what other advice do youhave regarding size, depth, layout, etc? Many thanks; I love yourshow! ---Steven in Reading, PA
Mike: In an effort to increase our usable garden area, I just completedconstruction of a 16 x 4 foot raised planting bed. We plan to use ourown compost as a topping, but need a good, economical material to fillthe bulk of the beds. Do you have any ideas? Thank you very much.
---Evan in Merion PA
Dear Mike: I love the show—your advice to put eggshells in the holewhen you plant tomatoes saved my German Johnson's last year! I have had4 new raised beds constructed this year and filled with mushroom soil.While this is pretty cool, the soil seems sort of heavy for what isessentially a container garden. Should I do something to lighten it up?
---M.J. in Wallingford, PA,
Hi Mike: I want to build a small raised bed garden for my 90 year-oldmother in Wilmington, Delaware. What should I use to construct thesides, how high should they be, and what kind of "dirt" should I fillthem with? Thanks,
---Ruth, also in Wilmington(where the earth is made of clay!)
Question. Let's begin with a littletreatise on raised bed basics, direct from the pages of my brand-newbook "Kitchen Garden A to Z" (Abrams publishers; 2004):
Raised beds warm up faster and drain better than flat ground gardens;provide astounding protection against floods; are much easier to weed,and provide your plants with a nice loose, 'friable' earth by creatinga visible barrier against the intrusion of soil-compacting feet. Raisedbeds can be any length, but should always be four feet wide. Thisprovides maximum growing space, while still allowing you to reach thecenter of the bed from either side without your big feet tramping downin the planting area. The lanes (walking areas) between the beds mustbe at least two feet wide; this may seem like a waste of space in theSpring, but trust me, it'll be a tight squeeze by Summer.
Map out your design with stakes and string. Use a garden fork or tillerto loosen up the soil in the areas that will become the beds, thenshovel soil from the areas that will be your walking lanes up onto thebeds until they're six inches to a foot higher than the lanes. Removeand save any big rocks you encounter. Remove and throw away any bigclumps of clay; clay soil cannot be improved—it can only be removed.Never step into the beds; always work with your feet outside their niceloose earth.
Unframed Beds: In the French Intensive System, raised beds are allowedto slope naturally to form mounds. These slopes provide 20% extragrowing room when you adorn the sides with small plants like alpinestrawberries, lettuces,and compactflowers.
Framed: Framing your beds provides a more formal structure and greaterprotection during floods. You can use pretty much any material exceptnasty stuff like old railroad ties and pressure treated wood. Among themost popular non-toxic choices are:
• Wood. Cedar, recycled redwood, locust, andOsage orange are all naturally rot- resistant. But many gardenerssimply use untreated pine boards or other inexpensive 'regular' wood.These frames will survive for many years, and return their nutrients tothe earth when they finally do decay. (And by that time you'll probablywant to change the design around anyway.)
• Stone. Many of us are 'blessed' withexcellent framing material in the form of all that rock and fieldstonewe had to dig up to have a garden. Instead of hauling this heavy stuffaway, use it to frame your beds. It's very attractive—and stone framescan extend your growing season by absorbing heat during sunny Spring& Fall days and radiating it back into the soil they protect atnight. Same for cinderblocks—which you could paint to look nice and/orposition with their 'holes' at the top and plant small flowers in thoseholes.
• Plastic & wood composites. Most lumberyardscarry at least one brand of faux landscape timbers made from recycledplastic and wood shavings. I used one of the oldest—"Trex"—to framesome of my beds a good decade ago, and the timbers show no sign of age(I wish I could say the same!). These products look like wood, can beworked like wood, and will last virtually forever. (See sites likewww.trex.com for more info.)
I like to use half garden soil (you'll be lucky to have that much leftafter you toss all those giant clods of clay) and half mushroom soil orother high-qualitycompost to fill my beds. Such composts are widely available inbulk, and provide all the food your plants will need this season—maybefor several seasons. M. J.: That compost may seem heavy, but it's aheck of a lot lighter than the nasty clay so many of us are cursedwith. But go ahead and lighten it up; you'll only make a good thingbetter! Buy big bags of perlite and/or vermiculite and mix some ofthese natural mined soil-lightening materials into your beds. (Justlike Mel Bartholomew says in the classic "Square Foot Gardening"!)
And finally, Ruth: At 90 years young, your mom should be done withbending over. Build nice, tall, two to three-foot high platformsfor most of her raised beds. Fill the bottoms with rocks—they'll makefor great drainage—and save the good soil for the top foot or so. Sizethem so that she can work at 'ground level' while she's sitting downand harvest things like peppersand eggplantswhen she stands up. Most tomatoplants are going to grow to be her size, so plant these in regularraised beds.
You Bet Your Garden Question of the Week ©2005Mike McGrath