April is a good month to start sowing root vegetables. My soil temps are still running in the low 40’s even in the raised beds, but most root crops will germinate in cool soils. However, with all of our recent rain it would be better to wait until things dry out a bit before seeding to avoid rotting seeds.
Let’s take a look at some of the more common roots to see what it takes to grow them well. There are many more roots to try: sunchoke, horseradish, rutabagas, salsify, and shallots - try something new and also try some heirlooms for fun!. Read up on them before growing as some can be invasive. First, a few essentials: (see separate section on potatoes)
General Root Crop Guidelines: Soil: All root crops like to have a loose, deep, well-drained fertile soil. If you are working with a soil that has a lot of clay, consider growing them in raised beds or even buckets on your deck. They all like a full day of sun. All, except beets which like a lower pH, like a pH of around 6.0 to 6.8 - you can get a pH test kit at local nurseries- test at the root level - about 6-8 inches down. Use an all-purpose fertilizer prior to planting unless you have amended well with compost or cover crop. Most root crops are light feeders but they do like to have nitrogen added because of our rains, and plenty of phosphorus (P), which aids in root development and increases the rate of growth. If your soil is low in P, it can be added through the addition of bone meal or rock phosphate (vegan). If you have added compost to your bed you probably have enough.
Planting: All root crops should be planted directly in the soil as they do not take to transplanting due to their long tap root. Follow the package directions for depth and spacing of seed.. Most root crops do better in a cool environment but for many of them making succession plantings every few weeks will provide you with mature roots all season long,
Care: Keep new seed beds moist and then assure one inch of water per week, watering deeply to get it to the root level. They will all need thinning to about a 2” spacing after they are up and sturdy but most thinning’s make a good addition to salads or braising mixes. As with all of these crops, rotate them from bed to bed to disrupt the pest and disease cycles. Keep weeded.
Beets - beets like a slightly more acid soil (6.2) so check the pH in your beet plot.. Each beet seed is actually a cluster of seeds so they definitely need thinning out but be careful not to disturb the ones you want to keep. Beet greens are high in vitamins and a good addition to salads or in braised dishes. Germination is increased if they are soaked in water for 24 hours before sowing. You may have a problem with leaf miners - if so, just snip off the affected leaves and dispose of them.
Carrots - Carrot seed is very small so seed thinly maybe using radish seeds to mark rows or put the seed in a small amount of sand and then sow the row. Cover lightly so soil does not cake on the surface. Check the maturity dates on carrots as they vary quite a bit. One trick I have used is to sow my whole 4x8 foot bed at one time using three different maturity dates (a 70 day,, a 100 day and a 240 day).That way I can do my bed all at once. If your soil is not deep or loose, try planting the shorter varieties. Carrots not having enough depth of soil or that are crowded may end up “forking”.
Because the Carrot Rust Fly is so prevalent here, protect against this pest with a complete covering of insect barrier cloth and secure all around the perimeter of the planting. Planting carrots with onions and a few chamomile plants in the bed has also worked for me to control the fly. Yellow sticky traps also might help. Check this web site for a discussion of this pest -http://cru.cahe.wsu.edu/CEPublications/eb0921/eb0921.html
Turnips - this is a great crop, useful in salads, stir-fry’s, stews, etc. For a long season and winter hardy with heavy mulch or stored. Turnips are easy to grow but are affected by several pests; root maggots and aphids are two. Fortunately a row cover (remay or insect barrier) will completely dispel these and some other pests. Thin out using the turnip greens in recipes and then harvest when they small, -1-2”, before they taste hot.
Parsnips - Buy fresh parsnip seed as the longevity of this seed is very short. Plant around May 1-15th for a nice fall harvest. Parsnips germinate slowly at a soil temp of about 60 degrees, and they take about 120 days to mature. This crop is also prone to injury from the carrot rust fly so a covering with a row cover is needed. They are better and sweeter after a fall frost. These roots are packed with nutrients and fiber!
Radishes - a very easy crop to grow and not fussy about the weather. There are a lot of varieties varying in degree of “hot-ness” so choose what you like to eat. Radishes grow fast and mature within a month, so for a c continuous harvest of radishes plant them every few weeks and harvest before they get too big, hot and pithy! You can plant radishes with either carrots or parsnips as the radishes will mark the rows early and be gone by the time the other vegetable needs the space.
Onions - You can grow onions from seed, transplants or sets. Provide additional fertilizer in the row beneath the seed, set or transplant. Onions react to the day length for growing and maturing so check to make sure what kind of onion you are growing. Make sure they get water and then lightly mulch them later on to keep them moist and cool during the hot part of the summer. For harvesting of storage onions allow the tops to dry somewhat and fall over.
Potatoes -. There are a lot of methods for growing potatoes: in the ground, under straw, in containers/ bags. I have had the best luck in the ground but check out internet sources for other methods or if you have space considerations. Try different varieties and maturity dates to enjoy over a longer period of time
Soil: Plant in well drained fertile soil. Potatoes like a lower pH of around 5.5. Adding sulfur will help bring down the pH if needed. Do not use fresh manure or go heavy on the Nitrogen or you will end up with lots of beautiful green plants and no potatoes.
Management: To get a head start on growing your potatoes, green chitting (or pre sprouting) is accomplished by putting the tubers in a low light setting at around 50 degrees for a few weeks. The sprouts will start growing but will be short and stubby so will come up faster when placed in the ground Planting whole seed potatoes protects them against decay but you can cut them to into pieces but allow for at least two eyes per piece. If you do cut your potatoes, dust with sulfur and plant right away or harden the cuts over a few days with high humidity. Give your potato bed or planter box a good dose of compost or well-rotted manure. Plant in a furrow about 4-8 inches deep and cover with 3-4 “of soil. When the plants are up about 6”, hill them up with the soil from the trench but do not cover the tops, Then provide another hilling after they are up another foot, but allow at least 6-8”’s of tops. Side dress with some kelp meal after each hilling. Keep light away from growing tubers. Make sure they have their required 1” of water weekly and mulch to conserve water, especially during tuber formation (before flowering) and tuber bulking and on to maturity. . Flea beetles are common here and leave a “shot-hole” pattern on the leaves - a light sprinkling of wood ash can help repel the beetle/ or try a spray of strained, diluted garlic .
Harvesting: You can “rob” the plants for a tasty treat about 30 days after flowering but for good storage, allow the plants to TOTALLY die back and then leave in the ground for another couple weeks for the skins to “set. Do not wash before storing.. You should get about 10 pounds of tubers per pound of seed planted. Watch for late blight which can attack the foliage and if left unchecked will affect the tubers as well.