in the garden

In the Garden: Roots, Tubers, Bulbs & Greens

By | March 01, 2011
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Garden Vegetables

Potatoes are romantically Irish and it just so happens that I almost always plant them on St. Patrick’s Day. Mid-March, spring break, it’s on the calendar so it keeps me on task and marks the start of another growing season.

Once the seed potatoes are in, then the work begins lining out rows of onion sets, then the peas — English, sugar and snow — spinach, kale, parsnips, beets, carrots and Bibb follow in succession. Early spring is the time cool-season crops thrive and are dependent on cooler — not cold — soil temperatures for the seed to germinate, flowers to bloom and fruit to set. From asparagus to spinach, the spring garden is ready to be put in. Spring planting — virtually all planting — benefits from the addition of “organic matter.” Organic matter is composed of formerly living plants and animals (or living animal byproducts, like manure). It usually means compost, well-rotted manure, decomposed leaves, etc., and mixtures of these items.



Asparagus is a perennial vegetable so if you’re planting it, be certain about where you locate it and be quite serious about preparing the planting bed. Asparagus will produce for decades if properly maintained.

To plant the asparagus root crowns, dig a 10-inch-deep trench and adds lots of organic matter to improve the soil. Space the crowns in the trench about 18 inches apart, spreading out their roots; only add the soil back around the crown, covering the crowns by a few inches. As new shoots appear above the soil add a few more inches until the plant is covered even with the original soil level. This will take several weeks.

Do not harvest asparagus from the first season’s growth. Allow it to go to fern and then cut the fern-like growth back after it dies. During active fern growth in the later part of the summer, fertilize using a balanced organic fertilizer.

The fern growth is critical to next year’s harvest because this is how the plant stores energy in the roots. Next May you can begin harvesting fresh asparagus, but only do so for about three weeks. During the third year you can increase your harvest time without jeopardizing further asparagus development. Once established, beds can be harvested into mid-June as long as there is adequate rainfall.



These can be directly seeded into the garden as soon as the soil is workable and warms to about 45°. Keep the seed bed moist until germination; do not fertilize and water deeply for root vegetables. The root vegetables will tolerate some shade but plant your peas in full sun and consider pre-soaking them in water and a bean and pea inoculant that contains a rhizobium bacterial culture that helps the pea roots develop nitrogen-fixing capabilities (good for the soil and good for the pea).

Other cool-season crops like broccoli, cauliflower, cabbage and Brussels sprouts do better set out in the early garden as seedlings; they all tolerate light frosts. If you haven’t already started them from seed, purchase them from your favorite garden supply store.


Onions can be planted out in the garden as sets (little onion seedlings) in very well-drained soil, with lots of organic matter. Dig trenches and sink the onion set so only about ¼ inch is sticking above the soil surface; hope for rain early in the season as the bulb develops and a dry period just prior to harvest. Provide steady nutrients by working a balanced organic granular fertilizer in trenches between your planted rows.

A successful onion harvest and subsequent storage success relies on day-length and variety. In Kentuckiana we should plant intermediate-day-length onions (these onions set bulbs when day-length averages 12 to 14 hours) such as Super Star, Candy, Sterling and Big Daddy; most of these prove to be good storage onions, too. Late July and August is when our spring-planted onions and potatoes reach maturity and are ready for harvest. If you want to harvest before they reach maturity, enjoy them at the table in short order, but if you want to store them it is important to harvest and cure them properly.

A clear signal that onions are ready for harvest can be seen above the soil; the tops of the plants will begin to flop over and die back. Once about half of the tops have turned brown and flopped over the onions are at their peak for harvesting. You don’t want to harvest too early because the bulb size will be small, they will cure slowly and be more likely to decay before you use them. Waiting too long increases the chances of decay, too. Once the tops flop and have partially died out, get to digging. Once dug, the onions must be cured: You will trim the tops back to two inches and lay the onions on a screen in a dry, well-ventilated, shaded place for about two weeks. As they cure, the necks shrink up and phenolic compounds accumulate and seal the bulb, preventing rot. Those onions with thicker necks will likely rot more quickly so sort those and use them first. Those that look clean can have the remaining tops snipped after two weeks of curing.

Onions should be stored at 32° with a low humidity level. Rot and sprouting during the bulb’s dormant period are more prevalent when they are stored at temperatures above 40°.



Select potato varieties that complement the way you cook.

The most versatile varieties include Yukon Gold and Red Cloud. Both are great for serving as “new potatoes” and also hold well in storage. If you have a history of pest problems, try Island Sunshine or Prince Hairy. Density and moisture content in a tuber make it better suited to certain preparations: Elba and Butte are good mashed or baked; Caribe and Carola are good for roasting and frying, and fingerling potatoes are handsome and delicious roasted whole.

Potatoes will grow in most soil types but working compost into the planting furrows is recommended to improve drainage and provide additional nutrients. Composted manure will provide the fertilizer requirements throughout the growing season, supplemented by spraying liquid seaweed or fish emulsion on the plants during active growth. Research suggests that fish emulsion deters deer grazing and some insect problems so that’s always my preference. Cut the seed potatoes into sections before planting, making sure that each section has two or three healthy buds, or “eyes.” These eyes become the roots and stems of the tuber.

You can usually get four good pieces from each seed potato. On average five pounds of seed potato will plant out a 50-foot row.

Plant your seed potatoes in furrows, about 12 inches apart and about three to five inches deep — shallow for fast emergence, deeper for less hilling duty. I plant on the deep side so I don’t have to hill the plants as much. Once the seed potatoes are planted, put straw or other mulching material down to moderate soil moisture, control weeds and to further protect the developing tubers from sun exposure. A couple of weeks after the foliage has emerged start putting soil around the stem to protect the developing tubers. If the tubers are exposed they turn green and take on a slight toxicity (they won’t kill you, though).

You can harvest small new potatoes after the plants have finished blooming in the summer, but for storage allow plants to reach maturity. Harvest potatoes for storage about two weeks after the tops of the plants have completely died back. Rub off excess dirt and cure your potatoes in a ventilated and shaded area for a couple of weeks before storing indoors. Keep them in a cool, moist, dark place that maintains a temperature between 40° and 50°. Don’t put them in the refrigerator; the cold turns the starches sweet.

Rotating your crop is essential for potatoes (and other vegetables in the nightshade family, like tomatoes) if you want to avoid pest problems.

For most gardeners it is not too much to ask that they hand-pick pests on a regular basis in order to protect their potato crop but there are some biological controls that can help offset larger infestations of potato pests. Using a floating row cover as an insect barrier early in season does a world of good in terms of protecting plants from Colorado potato beetles, leaf hoppers and flea beetles.



If you have never grown anything before, spinach is a good place to start because it is pest free, tolerant of cold and, if you make the right selection, can make it into the heat of the summer reasonably well. There are two categories of spinach: smooth-leaf, with its oblong leaves, and Savoy, with its thicker, rounder, darker green leaves. Choose varieties that are slow to bolt in hot weather such as Melody, Bloomsdale Long Standing and Italian Summer. Bolting occurs as the plant speeds growth after reaching maturity in order to go to seed; when this happens the plant turns bitter.

Spinach is a heavy feeder so work copious amounts of compost into the bed before seeding (most other lettuces and greens do not like extra fertilization, however.) For maximum yields you may consider side-dressing with a little cottonseed meal or using a diluted solution of kelp when the seedlings have several true leaves (those that are recognized as spinach leaves), and again two weeks later. You can expect about 30 to 40 days from seed to harvest.

Other lettuces, kale, Swiss chard, mustard, bok choy and our famed Kentucky Bibb are equally ready for the garden. Consider planting them on the north side of a taller summer crop that will eventually shade them when the weather turns warm. Greens can tolerate some shade better then most vegetables.

Snap Peas

Favorite Varieties

ASPARAGUS Jersey Knight
BEETS Bull’s Blood
CARROTS (any Nantes type) Bolero
KALE (for winter hardiness) Winterbor and Siberian
LETTUCE (Romaine type for summer heat) Jericho
ONIONS Sterling and Big Daddy
PEAS (for shelling) Mr. Big
POTATOES Swedish fingerling and Prairie Blush


Catalog resources for some favorites


ONIONS Dixondale Farms  
( or 877-367-1015)
POTATOES Wood Prairie Farm  
( or 207-425-7741)
LETTUCES & GREENS Renee’s Garden 
( or 888-880-7228


Local resources for favorites


ASPARAGUS CROWNS Bunton Seed, 939 E. Jefferson St.
Fresh Start Growers’ Supply, 
1007 E. Jefferson St.
RENEE’S GARDEN SEED Plant Kingdom, 4101 Westport Rd.
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