Grow-How: Root Vegetables
Our top tips for growing robust and hearty root crops.
Aroot vegetable is the best argument to not judge a book (and plant and person) by its cover. Growing out of sight, under the ground, root crops often escape gushing admiration due to their modest growing habits and the unimpressive, muted soil cloak they wear at harvest. But, dipped in water or sliced in half, the subterranean gems reveal themselves: bright ruby-red radishes, carnelian carrots, garnet beets, and pure-white turnips that look like giant pearls.
And, where the roots really shine is on the table: their spicy, raw crunch in a salad, or their creamy sweetness roasted on a cold day make up the foundation of many garden meals. Greens, herbs, fruits, tender summer treats like tomatoes and peppers are delicious seasonal treats, but roots endure, showing up on our plate year-round–pulled out from the ground or from the pantry.
Here are a few tips for growing great beets, carrots, celeriac, parsnips, radishes, rutabagas, and turnips.
Bed and Soil Preparation: This is often the root of root-vegetable growing problems. Root crops like a deep, loose, and well-drained soil to develop to full size. If your soil is suitable, till it well, then smooth the surface before sowing (to alleviate compaction after winter). If, however, your soil is very compacted and rocky (like so many places around here!), you will have much better success growing roots in a raised bed. Just make sure your raised bed or container is at least 10 square inches. Either way, add aged manure or compost to your beds or rows to provide additional nutrients to your plants. Most root crops do fine in partial sun, but full exposure is great.
Planting, Thinning, Watering, and Planting Again: Root crops grow best if sown directly to prevent root disturbance. All vegetables in this category prefer cooler weather and can be planted in spring for a summer harvest and in late summer for a fall (and winter storage) crop. For a steady supply of carrots, sow successively two or three times, in three-week intervals. Radishes are the fastest growing root and are great for successive sowing too. Spring and summer are also fast and small enough to inter-crop with any slower maturing plants, root or not, to save space in a small garden. Rutabagas and parsnips both require a long-growing season and should be sown as soon as danger of frost has passed.
Thinning is a step that cannot be skipped when it comes to root crops. Roots need space to stretch out and grow under ground, and crowding will result in a spindly-looking and unsatisfying harvest. The good news is that thinnings are delicious! Add these "baby greens" to salads and stir fries. Beets, carrots, parsnips, radishes, and turnips can be thinned (as soon as they are large enough for snacking) to two-inch intervals and the bulky rutabaga prefers eight inches of space. Carrots are notoriously slow to germinate; be patient–they'll come up!
Proper watering may mean the difference between a successful harvest or nothing at all, when it comes to root crops. About one inch of water per week is ideal. Whether it comes from rain or irrigation, it’s important to soak the soil with water, so that moisture seeps deep down. Surface watering can cause the roots to grow close to the surface and be small, misshapen, or dried out.
Weeding: Most root crops grow slowly at the beginning of their life and are unable to outcompete weeds, which is why weeding is crucial in the first few weeks of development. It’s best to prevent weeds from maturing by frequently hand-weeding or using a cultivator (to cut the weeds just below the surface). Carrots are especially sensitive to weed crowding.
Harvesting: Carrots, beets, radishes, and turnips can be harvested whenever they reach a usable size; but left to overgrow, they will lose flavor and become woody–so monitor their development. Rutabagas and parsnips, on the other hand, can stay in the ground until late fall (and they're even sweeter after the first frost!). Most roots will come out of the ground easily when pulled, but the longer ones, like carrots or winter radishes, can be stubborn. For those, reach below the surface alongside the root and wiggle it back and forth a bit or twist gently before pulling. If removing an entire crop at once, a garden fork is helpful to loosen the soil right next to the plants. All the root crops mentioned here have edible tops as well: experiment with carrot top pesto or a turnip greens sauté. Take a look here for details on how to know when different types of vegetables are ready to be harvested.
Our pup, Rutabaga, spooning a Gilfeather Rutabaga.
Storing: By keeping (most) root veggies cold (between 32 and 40 degrees) and humid (between 80 and 95%), their shelf life can be extended for weeks and often months. Although not too many of us are lucky enough to live in a home with a real underground cellar, the same result can be achieved in a basement, or even a buried cooler. For cellaring inspiration, take a look at this stream of ideas. And, for a brief overview of how to store fruits and vegetables, see this helpful guide from from Cornell.