Spring Gardens Start with Onions and Leeks

Begin by having supplies on hand:

• Compost — Loose, compost-rich soil benefits any crop. Add more seasonally as the soil compacts or washes
  away.
• Garden Soil Builder — Soil Mender’s blend of aged humus, manure, and alfalfa meal is excellent to amend soils intended for vegetables, and it can be used in place of soil if you’re filling a new raised bed kit.
• Organic Fertilizer — Try Espoma’s Plant-tone or Hasta Gro for their higher nitrogen content.
• Mulch — Pine straw is a good choice, especially for onions, which like light acidity; only a light layer is needed.

Select the Right Plants

Onions can have a wide variety of flavors from tangy to mild. Experiment with more than one variety and see which your favorite is. Onions can also be classified according to how much daylight they need in order to form bulbs, and North Haven Gardens only stocks those varieties that respond well to our light conditions.

Plant Onion Slips

• Dig a trench 4” deep, place a granular fertilizer like Espoma’s Garden-tone in the trench, then add 3” of soil on top of the fertilizer. Onions need fertilizer available as roots grow downward and begin to establish.
• Plant the onions in the top 1” of the trench, above the fertilizer – you will have some of the white showing. The plants will do much better if they are growing at or near the surface. Do not place any additional soil on top, as this will not allow the bulb to form. After planting, mulch lightly with pine straw.
• If you also want smaller green onions, plant the slips as close as 2” apart and harvest every other one early, prior to bulbs forming. This will leave room for the remaining plants to mature to full-size onions.

Plant Leeks

Leeks are a member of the onion family but with a milder flavor than onions. Leeks do not form bulbs but develop an edible 6”-10” stem up to 2” in diameter. Space plants 4”-6” apart in rows 6”-12” apart. To keep the edible stems white and tender, plant deeply – about 6”-8” deep – so that only a few inches remain above ground. Water slowly right after planting. Throughout the growing process, mound soil around the leeks to block sunlight and prevent the leaves from turn green and tough.

Care for Your Onions and Leeks As They Grow

• Water slowly and thoroughly after planting. Consistent moisture is important to successfully growing onions and leeks. Keep the soil moist but not wet. As the plants get bigger, their watering needs increase, but if the leaves turn yellow, reduce the frequency of watering. Near harvest time for onions, withhold water so that the skins will ripen for better storage after harvest. Protect onions and leeks from extreme cold early in the growing season, and keep the soil around plants weed-free, as they do not tolerate crowding.
• Fertilize. About 3-4 weeks after planting, watch for 5-6 leaves to have emerged, then begin fertilizing and repeat every 2-3 weeks. A low-formulation liquid like Hasta Gro is ideal. The size of the bulb depends upon the number and size of green leaves or tops at the time of maturity. For each leaf, there will be a ring of onion or leek. Onion bulb formation has begun when the soil near the bulb begins to crack and the neck is slightly softer. Stop fertilizing when you see bulbing begin. Pull mulch away from onion tops as they become visible so that they remain dry and continue to develop.

Harvest Onions

For green onions, harvest plants the size of a pencil before the bulb begins developing. When the stalks turn yellow and begin to fall over (generally in May), it’s time to harvest full-size onions. Harvest the bulbs by pulling or gently digging up the onion; lightly brush off excess soil and remove any bruises or soft spots, but leave the green tops. Do NOT wash onions; they must be cured first in order to store them properly.

Cure Onions

Before you store your onions, you must cure them, or they will rot. Drying is faster outdoors: Lay onions spaced apart in the shade for at least 3 days to dry. Indoors, lay onions in a single layer in a cool, dry place out of direct sunlight (a pantry or garage works well) for approximately one week. Good air circulation is key to preventing rotting. The bulb will feel dry and the outer layer will become papery. The top growth down to the neck will be completely dry when the onions are fully cured. Once dry, clip off any longer roots and cut the leaves off to about 1” from the bulb. Store onions in an onion net or basket in a cool dry place. If you use a net, tie a knot in between each onion so they don’t rest on each other; clip off onions from the bottom of the net as needed. Use pungent varieties first as they do not store as well as the sweeter varieties. Check onions often and remove any that begin to soften prematurely.

Onions and leeks are the foundation of many recipes and the foundation of spring vegetable gardens. For first-time gardeners – or avid gardeners with years of experience – a private consultation with a North Haven Gardens “Garden Coach” is an investment that will boost confidence and lend a fresh set of eyes and ideas to established landscapes and edible plantings. Learn more at https://www.nhg.com/garden-coach-program/.

Harvest Leeks

Approximately around the same time you harvest onions, use a garden fork to carefully harvest leeks when the shaft is about 1”-2” in diameter. Gently shake them, then rinse well. Since leeks are best used fresh, store
them in a damp paper towel in a bag with air holes in a refrigerator for up to 7-10 days, or blanch and freeze. Just before using, trim the leaves and slice the leek in half lengthwise, and rinse thoroughly to remove sand and soil trapped in the
layers.