The great raised bed failure: 5 steps to rehabbing yours

These beds were built to garden above the roots of the tree in the middle for fresh greens on California's north coast. (Maureen Gilmer/TNS)

These beds were built to garden above the roots of the tree in the middle for fresh greens on California’s north coast. (Maureen Gilmer/TNS)

Consider raising your beds another tier to provide a much deeper root zone. (Maureen Glimer/TNS)

To avoid creosote seepage from RR tie beds, replace the beams with cleaner materials. (Maureen Gilmer/TNS)

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By Maureen Gilmer

Time is the arbiter of what works in a garden and what doesn’t. It’s why anything new requires at least a decade to discover its weaknesses. The great raised bed failure is right around the corner as the older wood products and shoddy construction destroy structural integrity.

Just a few winters can find your boxes collapsed from rot and bugs and moisture if you used pallet wood or untreated salvage lumber. In the throes of spring passion, we use anything we can to get a garden in the ground. Now you realize how temporary raised beds are rotting when Mother Nature has her way. Thus salvage lumber used for greater sustainability can lead to earth-to wood contact for an unsustainable application.

Beds usually become weaker all the time. When a raised bed is full of soil, plants and mulch, the contents can be surprisingly heavy. When you add water, at about 8 pounds per gallon, the cumulative weight of rain or watering stresses the joints. This places great pressure on corners and seams.

You don’t want those seams to fail during the growing season, yet that’s when it usually happens. It’s very hard to fix in summer when full of plants, but during spring and fall, repairs and rehab can be done more easily. While planning your project, consider raising your beds if you have shallow root depth. Where soils are very difficult, the transition from one beam to two in height will ensure greater plant health, cooler roots and much greater drought resistance.

A simple five-step process helps you get your project under way on those mild winter days when the cold abates and the sun comes out. Here’s how:

1. Remove existing soil if it’s degraded to mostly woody matter and white perlite. Like all raised bed soils, the overall volume reduces as microbes and plants consume the fine humus. This leaves the beds chronically under-filled and marginally fertile. Stockpile excavated soil temporarily.

2. Inspect the newly exposed interior sidewalls of the bed, if they held up during the soil removal step. Use a screwdriver to

Source:: The Mercury News – Lifestyle


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