Winter is the perfect time to prepare for a spring vegetable garden, especially if you are just beginning.
There’s much more to growing vegetables than plopping seedlings into the ground. In our hot climate, where soils have very little organic matter and no summer rainfall, the best way to grow veggies is to plant them in raised beds.
What’s a raised bed?
The most simple and time-proven raised beds are bottomless wood boxes that sit on the ground. Each is filled with a soil mixture customized for vegetables.
Since vegetables tend to be “thirsty” plants, each bed gets plumbed with a dedicated irrigation system on its own valve, separate from the rest of the garden.
Planting in raised beds is different too. The plants can be grown closer together, which means more vegetables in less space.
There are endless variations of raised beds, but here I’ll cover the basics to get you started.
Find the Best Place for The Raised Beds
Choose a spot in full sun, near your kitchen, with good access to water. Set beds atop bare soil, NOT on top of grass, landscape cloth, weed cloth, concrete, gravel, or asphalt.
Choose the Right Materials
I am a fan of building raised beds with untreated wood, preferably redwood.
Line the bottoms with hardware cloth (not chicken wire, which breaks down sooner).
Cut hardware cloth a little wider and longer than the bed, and push it down into the bed from above so the hardware cloth molds up the sides. This helps keep gophers, voles, and other critters from burrowing in through the seams.
Plan for the Ideal Size
Width: The ideal bed is four feet wide. At that width, most adults can reach the center from either side without stepping into the bed.
Length: Length is not critical, though the most practical length is eight feet or longer.
Height: The easiest-on-your-back beds are 18 inches or taller. Cap the top with a horizontal 2x4 or 2x8 and you’ll enjoy setting tools, plants, or your rear end on it when you are working.
Decide How Many Raised Beds
Two or more beds allow you to rotate crops between beds each year.
Vegetables in the nightshade family (tomatoes, peppers, eggplants, tomatillos, potatoes) are highly susceptible to nematodes, fungi, and other pathogens that develop in the soil.
Rotating them from one bed to another helps keep those pathogens at bay. With two beds, you can plant the nightshade plants in one bed the first year, in the other bed the second year, then continue to alternate back and forth.
Irrigate Your Raised Beds
For best success, use in-line drip laid out in a grid atop the soil.
I like Netafim Techline EZ 12mm dripperline irrigation, with emitters spaced every six inches. Space grid lines six inches apart so there is an emitter every six inches in every direction. With this layout, water spreads evenly through the soil and doesn’t leave dry spots.
Choose the Right Soil
Fill beds with a soil mix (not “potting soil”) that is at least 40% organic matter, 60% soil.
Since beds hold a considerable volume—a bed 4’ wide by 8’ long by 18” tall holds just shy of two cubic yards—buy soil in bulk from a soil supplier, rock yard, or compost facility.
Mix in two to four cubic feet of compost, plus one or two cubic feet of worm castings (both compost and worm castings are sold by the bag)—the bigger the bed, the more compost and worm castings.
Fill each bed to the top. Water two or three times to saturate the soil and help it settle. I do not recommend using perlite in raised beds, since it eventually migrates to the surface.
Straw (not hay) is the best mulch for vegetable gardens.
Layer on three or four inches of straw to keep soil moist and temperatures moderated. Eventually the straw will decompose into the soil.
About the Author
Garden expert, designer, and author Nan Sterman specializes in low water, sustainable, and edible landscapes. She is the host of A Growing Passion, a TV show that explores how plants power the planet. Episodes air on KPBS television on Thursday nights at 8:30 and Saturday afternoons at 3:30, and on Monday nights at 8:30 on KPBS2. See past episodes online at agrowingpassion.com. Sterman’s latest book is the just-released Hot Color, Dry Garden available in bookstores, online, and on her website waterwisegardener.com.