Monthly Vegetable Gardening Tips
Think about seeds
Local nurseries carry a good selection of spring and summer vegetable seeds, but if you are looking for new or unusual vegetable varieties, or even the weird and wacky, catalogs will open up a whole universe of varieties to try.
When planning your garden, think about growing varieties that you cannot find at farmers markets or grocery stores.
Check out the Sacramento Vegetable Planting Schedule (EHN 11) for a general planting timetable.
You should be able to find bare root artichoke crowns in nurseries this month. If you want to give them a try, your best bet is to grow them in a location that gets morning sun and afternoon shade. They are grown commercially in the Monterey area, and they prefer a coastal climate. As a result, they tend to suffer in our summer heat, so growing them in an area of your garden that is protected from the afternoon sun will help keep them from stressing too much.
Artichokes are very large plants, so give them plenty of room (4 to 6 feet apart). They also make a great architectural statement, so think about planting one in your landscape. Do not be surprised if the plants slow down and go a bit dormant in summer. When the weather cools down in the fall, the plants should start growing again. Artichokes are heavy feeders, so fertilize them every month with a high nitrogen fertilizer.
Water artichokes regularly during the growing season. If they are grown only for ornamental value, artichokes are fairly drought tolerant; however, they will go dormant in summer heat.
Harvest broccoli and cauliflower
If you planted broccoli or cauliflower last fall, you may be able to start harvesting this month.
Harvest cauliflower when buds are still tight and unopened. With a sharp knife, cut off just below the head. If heads become over-mature, they tend to segment or spread apart and the surface becomes fuzzy. Use or preserve right away. The 'Snowball' variety may be grown as both fall and spring crops and can produce good heads within 2 months after transplanting. See additional information about growing cauliflower.
Asparagus is a perennial, cool-season vegetable, its long spears coming up year after year. So when you make the bed, do it carefully – your asparagus may be growing in it for 12 to 15 years or longer.
Asparagus grows from seed, but it is easier to buy 1- to 2-year-old crowns. The crowns are actually rhizomes (fleshy stems that store food for future plant growth) with roots attached on their under surface and the buds of spears that are just beginning to develop sticking up. UC 157 hybrid is a good variety for this area--it tolerates warmer winters and is resistant to Fusarium. When buying crowns, look for fresh, firm-fleshed roots. If they are shriveled or brittle, they may be old and won’t produce well, if at all. Plant crowns while they are dormant.
Plants need full sun, good drainage, and, most important, well-prepared soil enriched with lots of organic matter (well-rotted manure, compost, bone or blood meal, leaf mold). Asparagus is a good candidate for raised beds. Dig a 6 inch deep trench 12 to 18 inches wide and spread crown roots over slight mounds of soil spaced 12 inches apart; cover with 2 to 3 inches of soil. As plants grow, pull soil over the crowns until the trench is filled.
Harvest spears daily during the harvest period when spears are 6 to 8 inches tall and the tips are still tight. If the asparagus is allowed to get much taller, the bases of the spears will be tough. Snap or cut off each spear just below the soil surface. Cutting too deeply can injure the crown buds that produce the next spears.
When harvest is over, allow spears to grow and leaf out. This helps transfer energy to the roots for good spear development the next season. Asparagus has an attractive, fern-like foliage that makes a nice garden border. The tall growth can shade out other plants, so keep this in mind when deciding where to site your asparagus bed. Some gardeners prefer to support the growing foliage with stakes and strings to keep it tidy. Cut the foliage down to 2 inch stubs after freezing weather or when the foliage turns yellow. A 4 to 6 inch mulch of compost, composted manure, leaves, or other material added at this time will help control weeds and add organic matter and nutrients.
Weed the bed each spring before the first shoots come up to avoid accidentally breaking off spears. During production, it is best to pull rather than hoe weeds, if possible. A light mulch helps keep the soil surface from becoming too hard for the shoots to break through easily. Irrigate the bed during the summer for good spear production.
For additional information, see Growing Asparagus in the Garden from the UC Davis Vegetable Research and Information Center.
Potatoes come in many sizes, shapes, and colors. They generally have white flesh, but there are varieties that have yellow, red, or blue flesh.
Potatoes grow from seed potatoes. Seed potatoes are not seeds, but rather a piece of a potato. Do not be tempted to use grocery store potatoes or potatoes from your own garden. Soil-borne diseases, harmless to humans but potentially devastating for a potato plant, can be carried by potatoes. Instead, buy seed potatoes from a nursery that displays a Certified Seed Potato tag or from a reputable mail-order company that certifies the seed potatoes are disease free.
If the seed potatoes are not already cut, cut the tubers into pieces that are about the size of a small chicken egg. You do not need to cut small egg-size seed potatoes. Make sure each piece has at least one eye (small depression where sprouts will form). Store freshly cut pieces at room temperature for 1 to 3 days before planting. This allows the cut surfaces to dry and form a callus, which decreases rotting.
To plant, drop the seed pieces into furrows 3 inches deep with the pieces spaced 6 to 12 inches apart. Closer spacing gives more but smaller potatoes at harvest. Fill in the furrow to ground level. When the potato plants are 4 to 6 inches tall, “hill” them up by mounding soil to cover most of the leaves. Three weeks later hill again. This will make furrows between the rows that are at least 6 inches deep. You can also plant the seed pieces in raised beds: dig 3 inch deep holes using the same spacing and “hilling” technique as above. Apply nitrogen fertilizer at planting time.
Continue adding potting soil as the potatoes grow until the level of the soil is about 2 inches below the rim of the barrel. Mulch the top of the soil with organic mulch (straw, shredded leaves, compost); water and fertilize regularly. Harvest as indicated below by dumping out the barrel, or if it is too heavy, carefully reaching in with your hands to collect the potatoes.
Potatoes are shallow-rooted and need constant soil moisture. If soil dries after tubers have formed, a second growth will start when soil gets moist. This will cause knobby, cracked, or odd-shaped potatoes. Alternate wet and dry conditions can also cause cavities near the center of the potato. Cultivate carefully to remove weeds, taking care not to injure roots and tubers near ground surface.
Blossoming potato plants are sometimes an indication that new potatoes are ready to harvest; however, not all potato plants blossom. About 7 to 8 weeks after the plants emerge from the soil, you can gently use your hands to uncover the sides of the soil mound to harvest small immature tubers--new potatoes, which are extra sweet because their sugar has not yet converted to starch. Take care not to disturb the roots and remaining tubers on the plant. Then carefully pack the soil back around the roots and water the plant well. Be sure that all developing tubers are completely covered by soil. Long exposure to light can cause the skin to turn green. A poisonous alkaloid makes green potatoes taste bitter and should not be consumed.
Most of the crop should be harvested when vines die and/or the skin of the tubers is firm, not flaky. Remove vines before digging the tubers. Dig the potatoes when the ground is dry; dig carefully, making sure you do not injure or bruise the potatoes.
For more information on growing potatoes, see Potatoes, white (PDF, 15Kb) from the UC Davis, Vegetable Research and Information Center. Additional information is available in UC ANR Leaflet 2802, Growing Potatoes (PDF, 129Kb).
Cover crops planted last fall should be ready to cut down this month. Because the cover crop residue needs to decompose for 3 to 6 weeks before you plant your summer vegetables, count back from your planting date to determine when to cut it down. Environmental Horticulture Note #11, Cover Cropping in the Home Vegetable Garden, provides detailed information about growing cover crops.
If you did not start tomato seeds last month, you can do so this month for transplanting into the garden in late April or early May. Use a good seed-starting soilless mix in six-packs or other containers. After sowing the seeds, place planted containers on a seedling heat mat or in a warm place in your house. Bottom heat encourages seed germination. After the seeds germinate, remove them from the heat mat (if used) and place the seedlings in a brightly-lit window or beneath florescent lights. Fertilize the plants with half-strength fertilizer (kelp, seaweed, or fish emulsion are good choices) every 2 weeks. Plants should be ready to transplant into the garden in about 6 weeks after the soil has warmed to about 65°F. For detailed information about starting seeds indoors and acclimating them to outdoor conditions (hardening off), see Environmental Horticulture Note #96, Vegetable Gardening 101. Sacramento County Master Gardeners have compiled a list of some of their favorite tomato varieties in Garden Note #147. Check it out to get some ideas.
Sow seeds for leeks
Leeks are large, upright, non-bulbing types of onions. They are biennial, which means they germinate and grow in one season, survive the winter, and then flower and set seeds the next season. They thrive in well-composted, well-drained, fertile soil. Plant seeds ¼ inch apart and ¼ inch deep in flats that contain a well-draining soilless mix. Plant in the garden when plants are about 8 to 12 inches tall and slightly thinner than a pencil (ideally, but a little thinner is okay), around June or July. Gently remove the plants from the flat, then trim the roots to about 1 to 1½ inches and trim the tops to about 3 inches.
Begin harvesting when the leeks are about ½ to 1 inch in diameter (around October or November) and continue harvesting, taking the largest plants, until around mid-March. Plants will start to bolt (flower and go to seed) in spring, so be sure to harvest all of the leeks before they get over-mature, when the flavor can get bitter. Here is an easy way to harvest individual leeks without harming neighboring plants: Using a flat-tipped spade, plunge the spade straight down between plants, continuing on all four sides of each leek to be harvested. This severs the roots, making it easier to remove the plant. Then lift up each plant with the spade. Grasp the shank and pull it from the soil. If you try to remove the leeks without first severing the roots and loosening the soil, simply pulling them from the ground can break the stalk. Shake the leek to remove excess soil, trim the roots, and then rinse each plant with a garden hose to remove soil (leeks tend to hold a lot of soil).
Amend the soil in vegetable beds to get them ready for planting when the soil warms up to around 65°F and nighttime temperatures are above 50°F. Good soil amendment choices are compost, well-rotted manure, composted ground bark, last year's rotted straw, or other organic material. This will help sandy soil retain water and provide better drainage in clay soil, as well as improve the texture of both types of soil. Add a nitrogen fertilizer at planting time if a soil test indicates nitrogen is needed.
Let your vegetable garden soil dry out a bit. It should be moist but not wet, and dry enough to crumble when pressed in your hand, before you prepare it for planting. Loosen the soil to a depth of 6 to 10 inches with a spading fork and pulverize any clods into pea-sized granules. Spread fertilizer and compost and then lightly work into the soil, rake it in, and lightly water it in. Your beds are now ready to plant warm-season crops.
The unofficial "official" tomato planting day in the Sacramento area is April 28th (Lifetime Master Gardener and radio personality Farmer Fred Hoffman's birthday). If transplants are growing well (stocky, not root bound, and no flowers or fruit) and soil temperatures are around 65°F (usually late April or early May in the Sacramento area), plant them in well-amended beds. Because the weather can be unpredictable this time of year, take precautions to protect plants if nighttime temperatures get cold. It is not unusual to get rain with hail in early spring, so protect your baby plants. Wall-O-Water (photo, bottom left) or cloches (photo, bottom right) are good choices to provide protection from cold weather. Floating row covers (lightweight synthetic fabric) can be used to protect plants from light frost.
Check your soil temperature with a soil thermometer or compost thermometer before planting warm season vegetables. If the soil temperature is around 65°F and the nighttime air temperatures are consistently above 50°F, it is time to plant tomato and pepper transplants. Wait until the soil has warmed to 70°F before planting squash and melons. Be sure to provide protection for the plants if the weather turns cold.
Tomato and pepper transplants can be planted this month. Seeds of pumpkins, beans, corn, squash, cucumbers, and melons can be sown in the garden around the middle of this month. For interesting and unusual fall decorations, consider growing pumpkins or winter squash that are unusual and not your ordinary jack-o-lantern. Here are some varieties to consider.
|‘Jarrahdale’ - slate, blue-gray; shape is flat, ribbed, and very decorative||‘Musquee de Provence’ - big, flat pumpkins shaped like a large wheel of cheese; rich brown skin when ripe||‘Marina di Chioggia’ - large turban-shaped fruits with deep blue-green skin|
|‘Rouge Vif d’Etampes’ - beautiful flattened, ribbed large fruits are a deep red-orange||‘Long Island Cheese’ - flat, lightly-ribbed fruits look like wheels of cheese with buff-colored skin|
Watch for insects feeding on your veggies. Be sure to check tomatoes for hornworms and stink bugs. Also look for squash bugs on squash and pumpkins.
Handpick the critters and drop them into a bucket of soapy water. If you are not squeamish, you can also step on them or cut them in half with pruners (instant gratification!). For more information about these and other insects, check out UC IPM Online for tips on how to manage pests on vegetables and melons.
While there are few annual vegetables that are "drought tolerant," some varieties will grow successfully with less water. Most of these vegetables are heirlooms from arid parts of the world. If you are looking for somewhat drought tolerant beans to grow, here are three worth trying.
|Tepary beans - Grown mainly for dried beans, they are drought and heat tolerant. Plants that are over-watered will produce much foliage but few bean pods. Seeds are smaller than common beans and come different colors. Use tepary beans in any recipe that calls for dried beans.|
|Cowpeas - Beans in the cowpea group, such as familiar black-eyed peas, are drought tolerant to some extent. Usually grown for shelling or dried beans, cowpeas need little water and grow poorly if watered too much. They thrive in heat and full sun. Young cowpea shoots taste similar to mung bean sprouts. Some varieties (right) can be eaten as snap beans, but they are usually grown for shelling or dried beans.
|'Bolita' bean - This was one of the original varieties brought by the Spanish as they settled northern New Mexico. With its high protein content, the 'Bolita' bean became an important crop bean. This bean is similar to pinto, only more flavorful, more digestible and cooks faster. 'Bolita' bean is listed on Slow Food USA Ark of Taste, a catalog of over 200 of the best tasting rare, regional vegetables, fruits, and other foods facing extinction.|
Another July tip - If you planted corn in early May it could be close to harvest later this month. Corn is ready for harvest approximately 17 to 24 days after the first silk strands appear, but sooner in hot weather and later in cool weather. Harvest corn when husks are still green, silks are dry-brown, and kernels are full sized. Harvest at the “milk” stage. Use thumbnail to puncture kernel: if liquid is clear, the corn is immature; if milky, it is ready to be picked; and if there is no liquid, it is too late. Harvest ears by pulling down and twisting until the ear snaps off of the stalk.
If there is room in your vegetable garden, think about planting a fall/winter garden. Beets, carrots, and other cool-season vegetables can be planted this month. Check out the Sacramento Vegetable Planting Schedule to see what to plant.
Beet varieties that do well in the Sacramento area are those with a short number of days from seed sowing to maturity (generally those with 60 days or less as listed on the seed packet): ‘Egyptian Turnip Root’ (aka ‘Egyptian Flat’), ‘Ruby Queen’, ‘Golden’ (yellow), ‘Chioggia’ (red and white concentric rings… like a bulls-eye), ‘Albino’ (white), ‘Red Sangria’, and ‘Detroit Dark Red’.
Unusual, colorful carrots that are fun to try include ‘Lunar White’ and ‘White Satin’ (white), ‘Yellowstone’ (yellow), ‘Atomic Red’ and ‘Red Samurai’ (orange-red), and ‘Purple Dragon’ and ‘Purple Haze’ (purple skin with orange flesh).
Sacramento County Master Gardeners have had success growing all of the beet and carrot varieties listed above. See Growing Beets in Sacramento for more information.
Melons may be at their peak this month, but when should they be harvested? Cantaloupe/muskmelon is fully ripe when it pulls off the stem easily (it “slips” from the vine).
With other kinds of melons, a strong, pleasant aroma at the blossom (not stem) end is the best indicator of ripeness. These would include: the green-skinned ‘Persian’, the pink-fleshed ‘Crenshaw’, the yellow-skinned casaba, honeydew, and many European cross types.
A watermelon is a bit more difficult, but good indicators of ripeness include:
• the ground spot (the underside where the watermelon laid on the ground) turning from white to pale yellow
• the tendril opposite the stem of the melon has dried and withered
• the skin of the watermelon has turned from shiny to dull
• there is a dull “thunk” when you rap the melon with your knuckles in the morning.
Then keep your fingers crossed before you cut it from the vine.
This is the month to harvest pumpkins and winter squash for cooking and for fall decorations. Harvest after the vines have dried and before the first frost.
If cool-season crops are not going to be grown in your garden, and you have harvested all of your summer vegetables, it is time to get your garden ready for winter. Remove all plant material and dispose of it either in your compost bin or in your green recycle container. Do not put diseased, insect-infested plant materials, or weeds that have gone to seed in your compost, as all disease-producing organisms or weed seeds may not be killed during the composting process.
Now that vegetable gardening activities have slowed down, this might be a good time to jot down how your summer garden did.
This is also a good time to clean and oil your tools so they will be ready for next year. Be sure to store them in a dry location to keep them from rusting.