Troubleshooting Your Vegetable Garden
We gathered problems experienced by gardeners around the country and offered up some savvy solutions
You planted your favorites, then planned a season's worth of farm-to-table meals around your anticipated bounty. But you wound up with a harvest of bitter lettuce, cracked tomatoes, crooked carrots, and no idea where you went wrong. Don't toss those menus yet. This Old House surveyed gardeners around the country about quandaries ranging from no-show seedlings to overgrown zucchinis. Follow our advice on how to overcome them, and you'll be prepared to get this gardening season off to a fresh start—and a delicious finish.
Shown: Fruit-bearing plants—like tomatoes, cucumbers, and the eggplants seen above—do best with 6 to 8 hours of direct sun a day.
Quandary: The plants were beautiful. But the tomatoes never showed up.
Cause: Blame the weather. Many tomato varieties don't set fruit when nights are colder than 55 degrees F or warmer than 70 degrees. Scorching days pose their own set of problems; pollen diminishes when temperatures push above 85 degrees to 90 degrees. And the high humidity that makes so many of us sticky and sluggish plays tricks on pollen, too, making it hard for the wind to scatter it. No pollen, no fruit. Soil chemistry offers another explanation for a skimpy crop. Too much nitrogen fertilizer makes plants produce foliage like crazy—not fruit.
Cure: Go light on nitrogen-rich fertilizer (the label should say 4-12-4 or 5-20-5). And hedge your bets about when cold or hot weather will hit by growing some fast-maturing varieties as well as some that develop over a longer period. Your local nursery can help you choose types that thrive in your area.
Shown: Cherry-tomato vines are vigorous ramblers; avoid disease by staking the plants to keep the foliage off the ground.
Quandary: My beefsteaks were almost ripe—then they cracked or split.
Cause: Soil conditions that change from bone-dry to drenched can lead to vertical crevices or circular cracks around the stem—signs that the tomato's skin toughened and then couldn't stretch to accommodate new growth.
Cure: Keep soil evenly moist, but not soaking, for even growth. Choose crack-resistant varieties, like 'Jet Star' and 'Mountain Spring.' And pick big tomatoes slightly underripe.
Quandary: There are dark spots on the leaves. Foliage is yellowing and dropping off. Other plants look oily, splotched, and withered.
Cause: These are symptoms of various fungal diseases—including early and late blight.
Cure: Plant tomatoes where you haven't grown any member of the nightshade family for at least three or four years. Space plants so that fresh air can circulate. And look for varieties like 'Iron Lady,' 'Defiant,' 'Mountain Magic,' 'Mountain Merit,' and 'Legend,' all of which resist late blight, one of the most devastating tomato scourges.
Quandary: Talk about bitter!
Cause: It could just be the lettuce variety, but heat stress or a lack of water can also affect flavor.
Cure: Choose varieties—including butterhead types like 'Adriana' and 'Tom Thumb'—that are naturally sweeter than others, at least in their prime. For midsummer harvest, plant lettuce where taller plants will provide shade. Keep the soil moist, and watch the clock: Some research suggests that the glucose content of leaves picked between 7 and 8 a.m. may be double that of those picked in the early afternoon.
Shown: Lettuce requires consistently moist, but not waterlogged, soil to thrive.
Quandary: All my lettuce plants are a mess of flowers and stalks—no leaves.
Cause: A change in temperature or total hours of light—whether suddenly or seasonally—triggers a cool-weather crop's internal clock to "bolt," or transition to producing end-of-season flowers and seeds rather than the parts we want to eat.
Cure: Once your lettuce bolts, there's no turning back the clock. One of the simplest ways to extend your salad greens season is to avoid planting all your lettuce seeds or seedlings at once. Start new seeds every few weeks so that you can enjoy successive harvests.
Quandary: Something has scooped out holes in my beautiful beets, leaving tooth marks about ⅛ inch wide.
Cause: Voles, aka meadow mice
Cure: These 8-or-so-inch-long rodents spend most of their time in underground tunnels accessed through holes 1½ to 2 inches in diameter. Aboveground, voles like sheltered runways, so remove nearby grass, weeds, and mulch piles to eliminate their hidden habitat. Block voles from garden beds with a 12-inch-high fence made of hardware cloth that has openings of ¼ inch or less. Bury the bottom edge 6 to 10 inches deep. Mouse snap traps also work, but you'll need a
bunch, set crosswise to runways, with the trigger ends in the travel zone.
Shown: If you monitor your garden daily, you're more likely to spot harvest-ready plants at their peak of flavor.
Quandary: My carrots are ugly—twisted, bent, forked, or hairy.
Cause: Twisted roots signal overcrowding. Bent ones mean clay, rocks, or other obstructions got in the way. Too much fertilizer can lead to multiple roots. And hairiness means the soil was waterlogged or overfertilized. Microscopic worm-like root-knot nematodes can deform carrots in similar ways.
Cure: Plant where you have not grown carrots for three to four years in well-draining soil that is obstruction-free to the depth your carrot variety needs at maturity. Harvest carrots as they grow, so roots don't touch, to avoid overcrowding.
Quandary: I sowed all my seeds. They never came up.
Cause: The seeds may have dried out after you planted them. Or you might have planted too deep, so they didn't warm up sufficiently. Or you planted too early, while the soil was still too cold.
Cure: Wait to plant this cool-weather crop until the soil is about 60 degrees F. Teeny but rough-coated, carrot seeds take longer to sprout than many other vegetable seeds: Expect to wait up to 10 to 14 days for roots to grow and another week for leaves. Rake the soil, sow the seeds on the surface, and moisten with a fine spray of water. To keep the seeds from drying out, cover your rows with boards—or cardboard if you broadcast seeds over a bed. Lift the cover every day and mist to keep the soil moist. As soon as seeds sprout, uncover. If the weather gets too warm too fast, you can protect tender seedlings by rigging up temporary shade for a few days.
Quandary: The leaves are riddled with tiny holes.
Cause: Flea beetles. They look like black or bronze pinheads, about 1⁄10 inch long, and jump if you wave your hand near them.
Cure: These pests are a common problem for mustard-family plants (like broccoli, cabbage, Brussels sprouts, and kale) as well as nightshade-family members (such as potatoes, tomatoes, and eggplant). Tender seedlings are most vulnerable to all sorts of insect infestation, so it's smart to start with transplants, which are hardier. Here's another trick to try: Grow vulnerable plants between hairy-leaf types, such as radishes, which flea beetles don't like. Insect traps also work; you can make one by spreading Tangle-Trap, a sticky organic compound sold at garden centers, onto cardboard and going from plant to plant, flicking the invaders to their doom.
Shown: Frost sweetens the flavor of 'Lacinto' kale (aka Tuscan kale), which was grown in Thomas Jefferson's Monticello garden.
Quandary: My cabbage heads are splitting.
Cause: They may have been overwatered (either by you or by Mother Nature) after a dry spell. Or they might just be too mature.
Cure: If you don't want to pick all your cabbages at once and you want to leave heads in the garden after they firm up, gently pull up on the stem to break some of the root hairs, limiting how much water the plant can absorb.
Photo: Courtesy of BloominThyme.com
Quandary: I yanked out a wilted bunch of kale and discovered bumpy, swollen roots rather than the normal mass of fine ones.
Cause: Clubroot, a fungal disease
Cure: The fungus that causes clubroot can persist in the soil for a long time, so avoid growing plants from the mustard family in that area for at least seven years.
Quandary: The vines are smothering everything in their path, and the squash look like baseball bats.
Cause: You were overzealous in your estimate of how many of these robust vines you really needed—and then picked too few at harvest time.
Cure: If your garden is tight on space, avoid vigorous ramblers and look for bush varieties of zucchini that grow upright, like 'Fordhook' and 'Astia.' Compact varieties can even be grown in containers. If you go with the old-fashioned vines, control the common urge to plant every seed in the packet: Limit yourself to a couple of plants, then pick the zucchini two or three times a week, when they are between 5 and 6 inches long. Harvesting often encourages the plants to get back to the business of growing flowers, which eventually yields a larger quantity of squash.
Shown: Compact bush varieties of zucchini, like 'Tigress' (shown), are good choices for small gardens.
Quandary: My dream garden has vanished. Where peas or beans or corn were planted, there are now just holes pecked in the soil or pieces of half-eaten seedlings.
Cause: The early bird got the seeds.
Cure: Scarecrows were invented for this reason. Some modern twists play off the fact that birds are distracted by reflections: Crisscross your beds with string, and place reflective tape, glistening CDs, or shiny tin plates every few feet. Or cover beds with row covers until seedlings are several inches tall. Cindy Harrison, a gardener on Bainbridge Island, Washington, used this camouflage trick: "I planted pea seeds in between purchased pea starts. The birds fell for my ruse and did not find the tiny seed sprouts between the more established starts." Result: "A great crop!"
Shown: Plant legumes, like peas or beans, after a season of tomatoes to help restore nutrients to the soil.
Quandary: Seeds sprout and look full of promise. Then, zing! One morning, it looks like someone came through with a razor blade and cut all the young plants down at soil level.
Cause: Cutworms—fat caterpillars that burrow in the soil or hide under leaves during the day and come out at night to feed—are the culprits.
Cure: Cutworms can do severe damage in spring, before they turn into adult moths. Seedlings are especially vulnerable. You can start peas and beans early in pots and transplant them to the bed once the seedlings are hardier. Keep cutworms from encircling tender stems by sticking a twig into the soil alongside each new shoot, or protect them with cardboard collars.
You can reduce the risk of soil-borne problems by waiting three or four years before you grow members of the same botanical family in a plot where they were grown before. Parasites, bacteria, and fungal diseases tend to plague all members of a particular family: When you remove their hosts, they die out. Rotating crops is especially important for the nightshade family (such as tomatoes and potatoes), mustard-family crops (including cabbages and kale), and onions (like leeks and garlic). Giving a bed a rest makes sense, too. Plant a cover crop, such as red clover, for a season. When you eventually hoe or dig it into the soil, "it's like a dose of vitamins and nutrients for the garden," says Christine Mann, a gardener in Atlanta. "It keeps the good microbes and the earthworms happy."
Water deeply, using drip irrigation or a watering wand with a misting head held close to the soil. Take it slow, and don't get the leaves wet, which can invite disease. Dig down into the soil around the plant with your finger to make sure that it's moist to the touch around the roots, not just on the surface. And top the soil with weed- and pesticide-free mulch (like decomposed leaves, mushroom compost, or whatever's available where you live) to reduce weeds and preserve moisture.
Colin McCrate, founder of the Seattle Urban Farm Company, a landscaping firm that specializes in home vegetable gardens, tells clients that they'd do better spending 5 minutes a day tending their plots than devoting an entire weekend to them once a month. When weeds are tiny, you can almost brush them away. Vigilance also helps you to spot and act on insect and disease symptoms early. And you're more likely to harvest vegetables in their prime.
Read the label: Start off on the right foot by heeding the advice on the seed packet regarding planting times, soil preferences, seed spacing, thinning, etc.
Storage: You don't need to buy new seeds every year if you keep leftovers alive.
Testing: Spare yourself a no-show crop: Several weeks before the usual sowing time, place a few seeds from your leftover pack on a paper towel. Label, moisten, and enclose in plastic so that they won't dry out. If they don't sprout, toss.
Got enough seeds? Choose a crop (beets, for example), decide how long a row you want to plant, and a free online tool from Johnny's Selected Seeds will do the math for you.
Wait for warm soil: Seeds need more warmth to sprout than they do to grow once established. Optimal temperatures vary from variety to variety, but 60 degrees F is sufficient for many vegetable seeds. You can check the soil's temp the same way you do a roast turkey's: Stick the probe of an instant-read thermometer (meat or garden type is fine) 3 or 4 inches into the soil. Monitor a few times a day for several days.
Go to the tape: Crowding your plants invites disease and deformity. But when it comes to tiny seeds, like carrots, spacing according to the packet directions is easier said than done. To avoid the need to thin seedlings (and spare you all that bending over), use seed tape—a thin biodegradable strip studded with properly spaced seeds. Or make your own using inch-wide ribbons of toilet paper and water-soluble glue. Dab a toothpick with glue and use it to grab a seed and "plant" it on the strip (one every 2 inches, for carrots). Bury the tape at the right seed depth, then water and wait for the magic to get started.