Christy Wilhelmi is a self-described Garden Nerd. She even owns the url where she expounds all sorts of gardening tips, facts and advice. Her new book Gardening for Geeks compiles her years of expertise digging in the dirt in her Mar Vista backyard and in her community garden plot at Ocean View Farms. This weekend on Good Food Wilhelmi geeks out with Evan Kleiman about soil tests, raised beds and the little known fact that horn worms are black light reactive. (Meaning you can save your tomato plants by investing in a black light and picking those little green suckers off after the sun goes down.)
Below she answers our questions and even shares her garden blueprints.
I’ve noticed that you are a big fan of raised beds. What are the benefits to building raised beds instead of planting directly in the soil?
We typically think of raised beds for climates where the ground freezes over, but raised beds are beneficial if you have clay soil that doesn’t drain well. It also helps separate you from heavy metals in the soil (I always recommend that if you grow in the ground, pay for a soil test that includes heavy metal analysis). We have a lot of lead in our soils from turn of the century oil drilling, leaded gasoline, and mid-century lead paint. Raised beds make work easier for those with back issues, and they can help reduce pests to some degree as well.
Is there a particular material you like to use to build your raised beds?
I usually use cedar for clients, but my own beds are built out of Trex decking because it’s one of the only composite lumbers that is safe for direct soil contact and it’s guaranteed for 25 years, which is nice. I’ve also used reclaimed lumber and other materials for gardens. It all depends on your budget.
Do you recommend purchasing potting soil to fill the raise beds? Do you like to add any other inputs?
In an ideal world, we’d all make our own compost to fill our beds. But in the immediate need, I use a combination of coir and high-quality bagged soil amendments to build great soil. Most bagged potting soils use peat, which isn’t sustainable, so I mix my own with coir for clients. We’ll usually throw in some organic vegetable fertilizer and if the soil is sandy, we’ll use a little vermiculite. You can get bulk soil, but often times the delivery charge is more than the cost of the soil.
How do you irrigate your edibles?
I water my community garden plot by hand (have done that for 14 years), but my home garden has the Cadillac of irrigation systems. I have 8 beds and each bed has a mini-valve so I can program drip irrigation separately for each one. I’m pretty spoiled. For the winter months, we’re watering by hand from our rain barrels (usually from November through April) and when that runs out I turn on the drip.
Speaking of irrigation, I noticed that you grow corn in your home garden. I understand corn is a very water-intensive crop. Is it hard to grow in a home garden?
I don’t experience corn as needing more water than, say, lettuce. Once it gets going I water it with drip irrigation every other day or so for about 10 minutes. The trick is to plant at least 3×3 rows of corn otherwise it won’t pollinate. I plant a 4×4 bed with as many plants as I can fit and it works pretty well. This year I’m marking my calendar for 21 days after the silks come out to remind me that it’s time to harvest. I missed that window last year and ended up with tough corn. Now I have a lot of dried blue corn for cornmeal.
If your clients only have enough space for one raised bed, what do you recommend that they grow?
It’s so hard to choose, and it depends on the time of year. In spring/summer I’d say grow tomatoes and crops that keep giving, like pole beans and collards (harvest the outside leaves and they keep producing from the center all season). We’ll usually plant peppers, eggplant, herbs and if it’s still cool, some lettuces. In the fall I recommend growing all the greens: lettuces, kale, chard, and the brassicas: broccoli, cabbage, kale, cauliflower, kohlrabi. They can be planted a foot apart, so you can get a few different things into one bed. If a family has kids, I always recommend radishes and arugula because they sprout and grow quickly. And there’s nothing more satisfying than eating freshly harvested peas while gardening. Because those grow vertically they don’t take up a lot of space.
We’re midway into tomato-growing season. Any tips for gardeners who are nursing their tomatoes?
Don’t over water. A deep watering once a week, once tomatoes are established, or every 10 days once they’ve set fruit is sufficient. Feed them with compost mid-way through and again a month later. Add some organic veggie fertilizer or worm casting and water with kelp emulsion to keep them thriving. Keep an eye out for blight, which has been plaguing us in the last few years, and remove any diseased leaves.
Listen to Evan Kleiman geek out with Wilhelmi over soil tests and horn worms below: