Tips for Growing Root Crops
Nearly all root crops need extra nitrogen. This can be added in several ways, including compost, compost tea, fertilizers, manure, and by rotating them in behind nitrogen-fixating crops like legumes (peas, beans) and clover that’s been tilled in.
Most root crops require deeply tilled (or untouched if no-till gardening) soil and prefer lighter soils with a relatively high sand and low clay content.
With the exception of leeks and potatoes, all root crops should be grown on level ground (leeks and potatoes should be grown in little hills). All benefit when they receive a nitrogen additive about 1/3 of the way into their growth cycle (roughly one month from sprouting). This can be added through liquid fertilizer, compost tea with manure or urea added, or a top dressing of nitrate of soda.
In most parts of the country, root crops can be grown both in the spring and the fall for early and late harvests. The majority of root crops are cold tolerant, so they will do well growing into the fall and may even withstand the first frost. Nearly all can be “clutched” (have dirt mounded around them to expose only the leaves) in the fall to keep the crop from freezing.
Root Crop Varieties for the Garden
The most common root crops are: beets, carrots, kohlrabi, leeks, onions, potatoes, radishes and turnips.
Beets grow best in loose, light soil and are often grown in cold frames for extra crops or very early starts. The seeds are very small and it’s a good idea to put them in thick so that any that are killed by sudden bad weather or other problems will not affect the settings. Thin when the time comes and use the thinned sprouts on salads as a tasty addition.
Carrots prefer sandy soil and need deep soil to grow well. Commercially, the soil is often sifted for rocks, but in the home garden, a few carrots that bend themselves around a stone are not a big deal. You can alternate radishes and carrots in 6-inch spacing and by the time the carrots are pushing for the extra room, the radishes will be ready to pull. Late crops can be grown this way with onions as well.
Kohlrabi are more difficult to grow than other types, but should be started as a fall planting (late June, mid-July). Harvest when the tuber is about 2 inches around for tenderest eating.
Leeks the secret to getting good harvests of this plant is to continually “hill up” the rows. Add more soil (about 1/4 inch at a time) around the base of the plant every couple of weeks. This pushes the growth upwards and encourages the blanched, tasty lower trunk we’re familiar with.
Onions are happy when crowded together in six or eight inch spacings. When placing the prickers (seedlings), bury them about half an inch into the soil and cover with an inch of sand. When the plants are established above ground, add mulch.
Potatoes the best source of potatoes is your own larder. If you keep potatoes in a root cellar, those that are left over in spring will likely have begun to sprout eyes. Cut them into pieces so that each one has at least 2 eyes and plant when the good weather starts.
Radishes prefer soil that is ready to go and has no fresh manure or nitrogen in it. Plant them quickly in the spring. Add fertilizer once the plants are established and go easy with the nitrogen for the best, crisp roots.
Turnips / Rutabagas
Turnips will grow in both the spring and fall and prefer cool weather. Rutabagas (a cross between a turnip and cabbage) are best planted in the fall, about 100 days from the first frost.