Building better requires some thought [UPDATED]Published 8:26am Monday, April 2, 2012 Updated 10:28am Monday, April 2, 2012
Why would anyone go to the work and expense of building raised beds? Let’s start with backaches. We are all getting older and getting down on your knees to weed or pull carrots can be, quite literally, a pain.
Or maybe, you are a ‘competitive’ gardener. You want the first ripe tomatoes in the neighborhood. It could be the soil you have been dealt.
Heavy clay, or its opposite — sand, can be difficult to grow in.
Raised beds not only warm up earlier in the spring, they also have excellent drainage, especially nice if you have been dealing with clay in the past.
A raised bed prevents creeping Charley, crabgrass or other sneaky weeds from getting into the garden. Even Charley can’t climb a two-foot wall. However, Snow on the Mountain would sure make a try at it.
If you have no place or desire for a regular garden, a raised bed will give you fresh vegetables or a bouquet of flowers and the hummingbirds and butterflies that come with them.
If you actually do have great soil but are dealing with drainage problems, a raised bed could be only six inches high. If, however, it’s the stooping that gets you, shoot for at least two feet. Most plants need at least 12 to 18 inches of good soil to do well. Small shrubs will demand two feet of soil, and forget about a raised bed for a tree. There just is not enough soil in one, unless it’s huge, to protect the roots from our freezing winters. Make the bed at least 18 inches wide so you can reach all of it. It can be six feet wide if you can get at it from all sides.
Now, what materials are available?
• Pressure treated lumber. Never use this for anything you plan to eat. The chemicals it is treated with can leach into the soil. Wear a dust mask and goggles when you cut it, wash your hands right away to prevent ingestion and never burn the scraps.
The good part about this material is that it lasts about 20 years and is quite cheap.
• Cedar, redwood and other rot-resistant woods can be expensive and hard to find in needed dimensions. It should be treated with deck sealer to prolong life. The good part is that it is beautiful and long lasting.
• Landscape timbers, not railroad ties. They are expensive if you are building a large bed and they need reinforcing rods if you have more than two layers.
The good part, they are easy to place as they are big and heavy. (Get a football player to help lay them).
• Raised bed kits: Expensive for what you get, but quick to assemble and great for square foot gardening.
• Brick is gorgeous, classic and versatile. You can make the bed curved or make it round. Always use brick fired for outdoor use. The other kind crumbles.
The bad thing, it’s expensive and takes time and expertise to do well.
• Boulders, flat flagstones in particular, stack easily. Boulders or field rocks, not so much. It can be very attractive.
The bed will need to be lined with landscape fabric to prevent leakage of soil. The bad thing, smashed fingers and lots of time to get them to fit tightly. You don’t want them rolling off the wall. Can be expensive if you need to buy them.
• Concrete block is cheap, and easy to stack, but not very attractive and you should use metal rods if stacked over two high.
• Landscape block is cheap and easy to use, comes in the shape of bricks or cut stones or the pie shaped pieces that can make curves. Do buy the cap pieces to make the bed look more finished.
Next week we will discuss what to put in your new raised bed.
Bev Johnson is a master gardener in Otter Tail County.