We’re blessed with temperate weather in the Pacific Northwest that’s great for gardening … if only we could get a spade into our soil.
That’s the rub. Many of us have yards with terrible soil — compacted, poor-draining clay, depleted of nutrients. So it’s little wonder that many people eager to grow food are turning to raised garden beds, which permit you to add your own loamy, nutrient-rich soil without the backbreaking business of trying to dig up rocky or hardpan ground.
If you’re thinking about going the raised-bed route this summer, you need to act quickly, so your tender seedlings have a chance to get established before the high heat of summer is upon us. But gardening in raised beds is one of the easiest and quickest ways to get a good garden going, and one recommended by gardening pros.
Raised bed tips
Choose a raised bed that’s at least 18 inches deep to ensure that deeper-rooted vegetables have ample room to grow.
Cover the bottom with quarter-inch screen to deter gophers, but don’t use any other barriers that could impede water flow or stop roots from digging as deep into the ground as they want.
Some pro gardeners prefer 24-inch-deep beds, but remember, the deeper the bed, the more soil you must add. Some gardeners get around this by filling the bottom of their beds with dry leaves or half-finished compost so they don’t need as much soil, and the organic materials will gradually break down, providing more nutrients and beneficial microbes to your plants.
Keep the width narrow so you can easily reach to the middle of the bed.
If the bed is against a wall or fence, then make it no more than 3 feet wide, for instance. If you can reach in from all sides, then 4 to 6 feet will work.
Locate the bed in a sunny location.
Vegetables need at least 6 hours of full sun a day, so be sure you know how much sun your location gets before you fill your box.
One technique recommended by Lauri Kranz of Edible Gardens LA is, on a sunny day, use your phone to take photos of the location every hour from around 7 a.m. until evening. The timestamp on the photos will document how much sun your location gets before it moves into shade.
If the bottom of your raised bed touches native soil, keep it away from trees.
“Tree roots will gravitate to the easiest source of water and nutrients,” said Sophie Pennes of Urban Farms LA. “I haven’t seen this problem with citrus, but your bed shouldn’t be anywhere near an ornamental tree, especially a ficus.”
Use the best organic soil you can afford, preferably bagged soil so you can be confident about the ingredients.
“You’re wasting your money if you don’t use good soil,” said Conor Fitzpatrick, who builds cedar raised beds and edible gardens through his nursery business, Fig Earth Supply, in Los Angeles.
“Look for a soil such as E.B. Stone’s Recipe 420 that has 18 weeks of growing nutrients, or their Raised Bed Mix, which has 12 weeks of nutrients. Some of the cheaper soils only have four to six weeks of nutrients, and then your plants stop growing,” Fitzpatrick said.
Amend the soil with compost later in the growing season to replenish depleted nutrients and encourage beneficial microbes.
Fill your raised bed to the top because the soil will compress over time and get lower.
“The box itself can create a shadow on your plants if it’s not filled to the top,” Pennes said. “And then you get a moist environment in that area that’s partially shaded. Spiders and slugs love to live in corners of shady, moist places, so it’s important to fill your box all the way.”
Set up a drip irrigation system on a timer so you can adjust the watering based on what your vegetables need.
The most successful gardens use deep, infrequent watering to encourage roots to dive deep into the soil to find moisture and protection from the heat. Most professional gardeners suggest laying out a half-inch header hose across one end of the bed, and then attaching quarter-inch lines of soaker hoses with holes every 6 inches or so.
It’s most efficient to water your plants early in the morning, said Jamiah Hargins, of Crop Swap, a Los Angeles gardening collective. “When the plants are just touching sunlight is when they want to drink most of their water,” he said. “Then they’ve got that water to get through the day.”
Water for one or two minutes for a few weeks until the young plants get over their transplant shock and start growing, then train the roots to dive deeper for water by watering just two times a week for about 20 minutes (with drip irrigation). If water starts coming out of the bottom of the bed, reduce the amount of time by a couple of minutes, Kranz said.
Alternatively, you can bury 5-gallon nursery pots in your raised bed and plant around them, then fill the pots with water once or twice a week, so as the plants grow, the roots will follow the moisture deep into the ground. (Hand water around the base of the plants for the first couple of weeks until they are settled in.)
Mulching can help retain moisture, but there’s an alternative.
Use small wood chips — something easy to move with your hands so you can add amendments like compost to feed the soil and, in turn, the plants.
Most gardeners recommend intensive gardening that puts plants close together (instead of wide separate rows) so the interlacing leaves shade the ground and hold in moisture, making mulch unnecessary.
What to plant
Pennes, Savio, Kranz and Fitzpatrick recommend these plants as best bets for raised beds during the summer. They work well grown close to other plants and give you the biggest bang for your buck as far as producing food.
Tomatoes: Tomatoes are among the deepest-rooted plants, so be sure you have at least 24 inches of depth or access to the native soil. Most nurseries sell a plethora of varieties. Read the labels and choose varieties with different ripening times so you can spread out the tomato harvest season. Cherry tomatoes typically ripen early; the larger beefsteak and heirloom varieties can take several months to mature. Talk to your local nursery staff to see which varieties will do best in your particular region.
Eggplants: These plants are just beautiful in the garden, with their lovely star-shaped flowers and fruits that include the long, deep purple Japanese eggplant; the pure white, teardrop-shaped Caspers; and, my favorite, Rosa Bianca, a fat, creamy-colored fruit with violet stripes and a mild flavor. In the Seattle area they should be grown in the warmest, sunniest part of the garden.
Peppers: Here again, there are many choices for varieties, depending on whether you prefer sweet peppers or hot, with temperature ranges from spicy to blistering. If you choose super-hot peppers, keep them safe from children, who may be attracted to their beautiful colors. Hot habanero peppers look deliciously inviting with their reddish-orange skins.
Two of the easiest peppers to grow, Pennes said, are shishito, which are typically sweet but every so often can be fairly hot, and jalapeno, a must-have spicy pepper for salsa, pickling and almost any Mexican recipe.
Green beans: String a trellis along the back of your bed to support climbing varieties of string beans, which you can easily grow from seed. Or you can plant the bush varieties that don’t require any supports and start producing tender beans within a month.
The trick with beans is to keep the plants picked while the pods are tender.
Kale and chard: These indispensable greens grow easily in raised beds, and are great for quick stir-fry meals.
Cucumbers: These can be sprawling plants, but are much more trainable than a pumpkin plant. Plant six to 12 of them around a tall, sturdy bamboo pyramid trellis to train them upward and keep them happy, recommended Kranz.
Persian, Armenian, pickling cucumbers and round, yellowish lemon cucumbers are just a few of the tasty varieties. Kranz’s new favorite is the salt and pepper cucumber, which she discovered last year. “They sometimes look a little yellowish in skin tone, but they are absolutely delicious.”
Basil: Tuck in basil plants at the edges of your raised beds, around your water-hungry tomatoes, because this herb likes plenty of water, too. Try multiple varieties, like large-leaf, purple Thai and the intensely flavorful small-leaf globe varieties.
Carrots: Carrots are best grown from seed. Plant them in a line at the front of your raised bed, Pennes recommended. Carrots need plenty of room to dig deep in the soil, Fitzpatrick said. “If they feel they can’t go through [the soil], carrots will grow legs and arms and look like strange toys.”
Cilantro: Another indispensable ingredient for salsa and salads, cilantro should be planted from seed as they don’t like their roots disturbed.
Plant cilantro seeds in a high-water area where they can be shaded by other plants, like tomatoes, since they will bolt when temperatures get too high.
You can do successive plantings, but one bonus to cilantro is that once established, this lovely herb will reseed itself, said Pennes.
Lettuces and arugula: These are happiest when the temperatures are cool, during the late fall and winter. But with consistent watering and the shade of other plants (or via a shade cloth), you can grow arugula and lettuces in the summer, especially heat-tolerant romaine, butterhead and Batavian varieties.
Herbs: Tuck perennial herbs — such as sage, lemon verbena or marjoram — in the corners of your beds, Fitzpatrick recommended. Keep creeping herbs, such as mints and thyme, in separate containers, Pennes suggested. The herbs add fragrance and blooms to your garden, attracting pollinators.
Flowers: Every raised bed should have a few flowers, especially edible varieties, for beauty’s sake as well as to draw in pollinators that are vital to producing food, Kranz said.
Some great flowers for raised beds are cosmos, an airy flower with many colors that can weave in and around plants; bright orange and yellow nasturtiums; and tall zinnias, which come in multiple colors and thrive on being cut for bouquets.
African blue basil is Kranz’s favorite. It can be used as an herb but attracts pollinators when allowed to bloom. Its tall purple and white flower spikes make bees deliriously happy.
Plants that don’t work in raised beds
You can grow practically anything in a raised bed, gardening experts say, but because they provide limited space, it makes sense to grow larger, sprawling plants in another location.
For instance, pumpkin plants will easily overfill a 4-by-8-foot raised bed, unless you install a tall, sturdy trellis that can support the weight of the pumpkins, or if you train the plant to sprawl outside the bed.
You can train pumpkins to grow around corn stalks, but corn and pumpkins both require a lot of space and don’t produce any food until the end of the season, so consider whether you want to devote much of your raised bed to food you can’t eat until the fall.
Artichokes, as well as zucchini and other squashes, also take up a large amount of space, so consider planting those in a separate area.
Blueberries can do well in containers, but again, they can grow very large when they’re happy, so consider planting them in their own large pots.
This story originally appeared in Los Angeles Times.