We’re blessed with temperate weather in Southern California, perfect for growing all kinds of vegetables and flowers year-round ... if only we could get a spade into our soil.
That’s the rub with SoCal gardening. So many of us have yards with terrible soil, often compacted, poor-draining clay, depleted of nutrients. Little wonder that so 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, if you follow these tips:
1. 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 and stop roots from digging as deep into the ground as they want.
- Some pro gardeners prefer 24-inch 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.
2. 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 keep it 3 feet wide, for instance.
- If you can reach from all sides, then 4 to 6 feet will work.
3. 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 L.A. is to choose a sunny day and use your phone to take photos of the location every hour from around 7 a.m. until the evening. The timestamp on the photos will document how much sun your location gets before it moves into shade.
4. If the bottom of your raised bed touches native soil, keep the bed away from trees. “Tree roots will gravitate to the easiest source of water and nutrients,” said Sophie Pennes of Urban Farms L.A. “I haven’t seen this problem with citrus, but your bed shouldn’t be anywhere near an ornamental tree, especially a ficus.”
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5. 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.
- “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.
6. It’s important to fill your raised bed to the top because the soil will compress over time and keep getting 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.”
7. Set up a drip irrigation system on its own 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 attach quarter-inch lines of soaker hoses with holes every six inches or so.
- It’s most efficient to water your plants early in the morning, Jamiah Hargins of Crop Swap said. “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).
8. Mulching can help retain moisture, but there’s an alternative.
- Use small wood chips — something easy to move with your hand 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.
Plants that don’t work in raised beds
You can grow practically anything in a raised bed, gardening experts say, but because you have limited space it makes sense to move larger, sprawling plants to 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 you train the plant to sprawl outside the bed (happy pumpkin plants can easily take over a garden space).
You can train pumpkins to grow around corn stalks in a three sisters garden (adding beans to grow up the corn stalks), but corn and pumpkins require lots of space and don’t produce any food until the end of the season, so consider whether you want to devote your raised bed to food you can’t eat until the fall.
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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 do well in containers because they need acidic soil, but again, they can grow very large when they’re happy, so consider planting them in their own large pots.
Warm-season veggies that work best in raised beds
Here’s a list of plants that Pennes, Kranz and Fitzpatrick recommend as the best bets for raised beds during the summer — plants that work well grown close to other plants and that give you the biggest bang for the buck as far as producing food.
Note that cool-season plants, such as broccoli, celery and lettuce, are better to plant in the late fall and winter, because hot temperatures cause them to bolt (flower and go to seed) quickly and turn bitter. But if you get them planted soon you might be able to squeeze out a crop before our high-heat days in July, August and September, especially if the plants are shaded by taller crops like tomatoes.
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- Tomatoes are among the deepest-rooted plants, so be sure you have at least 24 inches of depth or access to the native soil. Thanks to our national obsession with this juicy tasty fruit, 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 what varieties do best in your particular region, especially if you live in a coastal area where cooler temperatures make it hard to get these sun-loving fruits to ripen. Check out the tips for coastal growing on Tomatomania’s website.
- These plants are just beautiful in the garden, with their lovely star-shaped flowers and fruits that range from the long, deep purple Japanese eggplant to pure white, teardrop-shaped Caspers or my favorite, Rosa Bianca, a fat, creamy colored fruit with violet stripes and a mild flavor.
- Here again, the choices are limitless, 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 jalapeño, a must-have spicy pepper for salsa, pickling and almost any Mexican recipe.
4. Green beans
- String a trellis along the back of your bed to support the older climbing varieties of string beans, which you plant by 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.
5. Kale and chard
- These indispensable greens grow easily in raised beds, and are great for quick summer stir-fry meals.
- Kranz said her okra performed beautifully last summer, especially the red burgundy variety.
- Pro tip: Pick okra when they’re very small, not much bigger than the first joint of your thumb, suggest the folks at one of my favorite farmstands, Corona Farms in Riverside. Wash and roast them for a delicious treat.
- These can be sprawling plants too but are much more trainable than a pumpkin plant.
- Plant six to 12 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 salt and pepper cucumber, which she discovered last year. “They sometimes look a little yellowish in skin tone, but they are absolutely delicious.”
- Tuck your 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, from the large-leaf to purple Thai and the intensely flavorful small-leaf globe varieties.
- 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.”
- Another indispensable ingredient for salsa and salads, but be sure you plant these from seed — they don’t like their roots disturbed.
- Try to put 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.
- Be prepared to do successive plantings, but one bonus to cilantro is that once established, this lovely herb will reseed itself, said Pennes.
11. Lettuces and arugula
- These are happiest when the temperatures are cool, during the late fall and winter in Southern California.
- With consistent water and the shade of other plants in the bed (or a shade cloth), you can grow arugula and lettuces in the summer, especially heat-tolerant romaine, butterhead and Batavian varieties.
- Check out these tips by SoCal garden blogger Greg Alder about growing lettuce in summer, and remember, it’s going to be tough to keep lettuce happy in the hottest months, especially in inland areas, so get it planted now.
- Tuck perennial herbs in the corners of your beds, such as sage, lemon verbena or marjoram, 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.
- Every raised bed should have a few flowers, especially edible flowers, for beauty’s sake as well as to draw in pollinators so 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.