The Farmer Diaries
Texas farmer weighs pros and cons of raised beds in gardening
Raised beds have cropped up in backyard gardens just about everywhere in Texas. Typically 8 feet wide by 6 inches tall, they promise a near work-free way to grow herbs, greens or a couple of tomato plants.
I've dabbled with raised-bed gardening since I was a teen in the '80s. I used to see them on a PBS show called Square Foot Gardening. Host Mel Bartholomew's method of growing vegetables in small, tidy beds separated by mud-free pathways seemed better than tilling an entire field, only to plant seed in a fraction of the prepared soil. Mulching, watering and weeding were easier in Mel's bite-sized plots.
I'm in my sixth year of using raised beds, with a setup of more than 30 in my garden. I've reaped some benefits, but I've also come to realize that they're not the cure-all for what ails the farmer. In fact, for every pro, there's a corresponding con:
Pro: Raised beds warm up faster in the spring and start crops off sooner.
Con: Raised beds get hotter in the summer, raising soil temperature higher than crops can endure.
Pro: Raised beds have good drainage.
Con: Raised beds do not retain moisture well and must be watered daily, sometimes twice a day, in the hottest part of summer.
Pro: Raised beds can be filled with sterile, weed-free soil and bagged designer dirt.
Con: Raised-bed soil that has a different texture from the ground cannot efficiently wick up moisture from native soil underneath the bed.
Pro: Raised beds are small, with neither weeds nor crops beyond arm's reach.
Con: Raised beds are small with no room to grow melons, beans, peas or any crop that vines out or needs a large area for a harvest to be worth the work.
On the plus side, the good drainage of raised beds rescued my crops in 2010, when it rained every other day from April to June. The soil became so saturated that water accumulated in some areas up to half a foot deep.
If not for the height of the soil in the raised beds, my plants would have drowned, and I'd have lost several months worth of work. Instead, they sat healthy and safe in soil that was slightly above water level.
But monsoon-like conditions are rare in Texas. More typically, we have drought — as in the summer of 2011, when we broke the record for the number of consecutive days at or above 100 degrees. That's when the cons of raised beds wrecked my garden.
No matter how much water I poured into my beds, my plants faltered. Despite frequent waterings and inches of mulch, soil temperatures rose too high — a direct result of all the surface area that the sides of a raised bed add to the soil around plant roots. Unlike native soil that draws heat away, raised beds are cut off from the natural heat sink that occurs with soil at ground level.
That summer, my plants were cooked by mid-July. Strolling through the beds at sunset smelled like steamed veggies — it was just that hot.
They are indispensable in fall and winter, when frequent rainfall makes drainage a priority. In the winter, elevated soil temperatures boost plant growth. Also, raised beds are easier to protect from frost.
For root crops and greens, raised beds remain a sort of living produce aisle near my house right through the fall. I credit raised beds for my year-round harvest, even when the weather gets cold.
They're neater. The pathways keep my shoes clean, no matter how muddy the soil is under the landscaping cloth. And finally, the beds offer focused spots for vegetable production.
But for summer growing, I plan to lower the soil to ground level in the majority of my raised beds. I may also replace the tall frames with simple edging.
At ground level, they'll no longer be suitably called raised beds; perhaps they should be called framed beds. I may even find that I need to raise and lower the soil levels in each bed as the seasons change.
I've had to adjust the vision I had of enjoying trouble-free food production with raised-bed gardening. Raised beds are not the last word in growing food.
But they are a useful tool with advantages to exploit in specific applications. No attempt to opt out of industrialized agriculture can succeed without a little bit of effort.