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Wednesday, November 21, 2007

Gardening Basics: Onions

How Onions Grow
By: the Editors of National Gardening
There are more than 300 widely scattered species of onions in the world, and the bulb onion we grow is just one of them. The onion is a biennial plant, which means that it grows one year and produces its seeds the second. Between these two seasons onions have a dormant phase, which helps us gardeners.

Onion's Growth Cycle

The first-year onion plants begin their growth by putting out green top leaves during the cool weather. They store a lot of energy in those leaves. When the weather gets warmer and the days longer, the plants stop putting out new top leaves. Instead, they take the energy from the leaves and store it in the expanding bottom bulbs. Eventually the leaves fall over and shrivel up and the plants appear dormant. Inside the bulbs, however, the plants are storing the energy to put out flowering seed stalks when they start growing again. That's the goal of any plant - to produce the seed to keep its species going.

Onion bulbs are best for eating, cooking and storing before they've started to put their energy into making seed. That's why gardeners harvest onions after just one season and pick off any seed pods as soon as they appear.
Planting Onions
By: National Gardening editors
Plant your sets early in the spring. Onions do best if the temperature is cool when they start to grow, and warm as they mature. Northern springs are certainly cool -- and often frosty! But as the saying goes, "You can't kill an onion -- even with a hammer!"

Frost just won't harm sets. As soon as the ground can be worked in the spring, put the sets in. In the North that's usually in late March and early April. Gardeners in the mild winter areas of the Deep South can plant their sets in the fall and get a plentiful supply of fresh onions throughout the winter months.

Why Onions Form Bulbs

Onion sets you plant in early spring will put on a lot of green top growth before they make bulbs. You may ask, "Why don't the bulbs start forming right away?" The answer is that before the plants can make bulbs, they first have to store energy in the top green leaves. Then they must wait for nature's signal to put this energy into bulb making.

The plants usually get the message when the day length and the temperature are right. The onions don't care how old they are or when they were put in the ground; when conditions are right, they simply stop making new leaves and start using the energy they've stored to make bulbs. The size of the onion bulb is determined by how much energy there is in the top green leaves before the light conditions signal to start diverting energy to the bulbs. The more green growth before this time, the more energy there is and the bigger the bulb will be.

Early planting is important because it gives your onions plenty of time to grow tops and to store a lot of energy for the bulbs. If you put your sets in late, they won't have the time for a lot of top growth. As a result, there won't be much energy available when nature whispers to the onion plant, "Make a bulb."

The Wide-Row Method

Plant sets three to four inches away from each other in wide rows (or a little closer if you plan to harvest them when they're small). Wide rows are useful for onions and many other vegetables because you can grow much more using less space. That's especially important if you only have a small plot. Here's why:

If you plant 100 onion sets three inches apart in a single row, your row will be 25 feet long. If you allow a few inches, say three, on each side of the set, the row will be six inches wide. That's a total of 121/2 square feet of garden space for 100 sets. But with a wide row 15 inches across, putting the 100 sets three inches apart in all directions, your row will be just 5 feet long and 61/4 square feet. A wide row is easier to water, weed, fertilize and harvest, too.

In the Ground

There's no need to make trenches or special holes for the sets. Just grasp them at the top (the pointed end) with the root end down and push them into well-prepared soil the full depth of the bulb. The soil should just barely cover the top of the onion sets. If you have some tiny sets, plant them at least an inch in the ground, so they get good contact with the soil. The sets will get a better start. After you've got your sets in the ground, firm the soil around them with a hoe.

Remember, if a set is planted too shallowly, it takes a long time to get started. It's important to push the bulb all the way into the soil. It gets the onion off to a good start for producing a lot of top growth. If the onion sets are a little too deep, it won't hurt. Later, when the bulbs are expanding, pull some of the dirt away from the sides to give the bulbs room to expand.

You may not want to plant all your sets at once. Try keeping back a few handfuls in the refrigerator. When you start harvesting some small onions to eat raw or use in salads and other dishes, replace them with sets from the refrigerator. Just remember that onion sets planted later in the spring won't develop into large onions.
Growing Onions
By: the Editors of National Gardening
As with most vegetables, you can start onions from seed in the garden. But many onions have relatively long growing seasons and onion seeds don't germinate quickly, so it's often better to start the crop another way. You can set out transplants, or you can plant "sets" which are simply half-grown onions.

Where Sets Come From

Many sets are grown from seed on big farms near Chicago. The onion seeds are planted very thickly. Super-crowding of the plants makes the competition for water and fertilizer fairly stiff, so the plants never get very big and the resulting bulbs are quite small.

The small onions are harvested in the late summer or fall and dried for a month or more to rid them of moisture that could cause rot. Then the sets are stored until gardeners need them the following spring.

It's said that Chicago got its name from onions. Indians, who once lived nearby, called the place "Shikako" which means "Skunk Place" after the strong smell of wild garlic, onions, and leeks that once flourished there.

Buying Sets

In the North you'll find the first onion sets of the year at garden centers when there's still snow on the ground.

Using sets is probably the most popular, convenient, and dependable way to get onions started. They're very easy to plant, and you can harvest your first eating onions sooner than if you started from seeds.

Stores usually sell only a few varieties of sets, such as long-keeping white and yellow varieties and a red type or two. You can also grow sets yourself during one season for use the next year.

Sets are sold by the pound or by the scoop; each set is one onion. When you buy onion sets, watch the size. Sets that are smaller than 1/2 inch in diameter take longer to grow, but they'll still produce. Sets larger than 3/4 inch in diameter are very apt to "bolt" or grow seed pods in a hurry after you plant them. If you let them grow seed pods (a pod looks like a miniature version of the domes on the towers of the Kremlin in Moscow), the plants put energy into the seeds and not into the bulb. The bulbs will be small, tough and won't keep, so pick the pods or seed stalks off as soon as you see them.

The most dependable sets are the size of marbles -- 1/2 to 3/4 inch in diameter -- and are quite firm.

Growing Your Own Sets

To save some money and have a little onion fun, you may want to grow your own sets. Here's how to do it: In July in the North, or August farther south, create a small section of your garden to plant a good storage onion such as 'Yellow Globe'. Sow the seeds about 1/4 inch apart in one-foot-wide rows. Give the plants some fertilizer and just let them grow without thinning them at all.

Shortly before the first frost, bend the tops over. Wait a week or so and then dig the small bulbs out of the ground. After curing them for a few weeks, store them in mesh bags in a very cool (40oF) dry, dark place. The following spring you'll have plenty of sets on hand.

Most southern gardeners don't bother with growing sets because they have a pretty long season and don't always need the head start that sets give. If you like to experiment, here is one method that works pretty well in the South; select a short-day onion seed variety that's a good keeper and in early March sow it thickly in a wide row and leave the onions to grow. As they'll be very crowded, the bulbs won't get oversized. Harvest the bulbs when the tops wither from the hot summer sun. Dry them in the sun for a day or so and store them in mesh bags in a very cool, dry place. In the fall you can set them out in the garden again. They'll put on a little root growth before it gets cold and when the weather warms up in the spring, they'll pop back to life giving you very early onions. Of course in the deep South, where the winters are quite often mild, you can plant sets in the fall and harvest onions throughout the winter.

Buying Transplants

The best way to start big-bulb, European-type onions is from transplants. These are thin, young onion seedlings, and the optimum planting size is when they're just the size of a pencil. You can send away to seed or plant companies for bunches of transplants, or you can sometimes buy them at your local nursery. To get mail-order transplants, order the varieties you want sometime during the winter from companies in southern states; they'll ship them to you in the spring. You have to order by the bunch (75 to 100 plants in each bunch). As with many other things, it'll be cheaper if you order in quantity, so getting together with friends on a big order can save you a little money.

Taking Care of Mail-Order or Nursery Plants

The first thing to do when the plants arrive is to unwrap them. The onion plants develop a lot of heat when banded together, and heat encourages rot in onions. Next, put 1/2 inch of water in a shallow baking pan, and stick the roots in the water just enough to get their "toes" wet. They'll revive quickly. Plant your onions as soon as you can after receiving them. If you can't plant them within a few days, forget the bath. Put the unwrapped plants in plastic bags and store them in a cool, dry place until you can plant. The refrigerator is a good spot!

You can also "heel in" your transplants until you have time to plant them where they belong in the garden. Just dig a shallow trench out in the garden (or use a container), set the plants a couple of inches deep and firm the soil tightly around them. Soil in the spring is usually wet enough to keep the roots from drying out.

If any plants have a bad odor or are slimy or slick, they're probably rotting. Separate them from the others right away and throw them out. They won't make it in the garden.

Growing Your Own Transplants

There's a tremendous satisfaction in growing your own plants indoors for transplanting. For one thing you have the benefit of choosing from more varieties.

Buy your seeds early enough to start your plants anywhere from 8 to 16 weeks before the last hard frost in your area. Start the seeds in a 4-to 5-inch deep flat filled with very rich, sterile, loose soil. Sterile soil is free of weed seeds and harmful disease organisms, so the onion seeds have a better chance at the start. The various potting soil and starter mixes on the market are good, but mixing in extra fertilizer before you plant is a must. One or two tablespoons of 5-10-10 fertilizer added to every gallon of potting soil works fine for onions and other vegetables.

Sprinkle the seeds into the soil and gently press them into the soil. Try to space the seeds about 1/4 inch apart, but don't fuss about it. It's impossible to get them spaced exactly right, and you can always thin them if they get too close. After sowing, just barely cover the seed with a little more soil or sand and tamp it down.

Next, moisten the soil and cover the flat with a sheet of plastic and then some newspaper. The plastic creates a greenhouse effect retaining the moisture, and the newspaper keeps the temperature even. (Onion seeds don't need light to germinate.) You won't need to water again until you take off the newspaper or plastic.

Put the flats in a nice, warm spot around 65oF or 70oF if possible. (Don't worry too much about the temperature being exactly right. Onion seeds will germinate anywhere from 40oF to 80oF; they simply prefer a steady 65oF to 70oF.)

Don't put the flats on a window sill before the seedlings come up. The temperature there fluctuates too much: On a sunny day it can rise to 90oF or more, but at night it can be the coldest place in the house. That's not good for germination; onions need an even temperature.

When the seedlings sprout, remove the plastic and newspaper and put the flats by a window or under lights. They won't need too much attention. Just make sure they get enough water, and you should add a little fertilizer from time to time -- about a teaspoon in water every two weeks is good. Pour it around the edges of the flat so that the water spreads across the whole area.

In a few weeks, you'll notice the tiny plants getting tall and spindly. That can be a problem, unless you turn it into a plus. It's very important that your onion seedlings not fall over and get too skinny to transplant, so when they're three inches tall, cut them back to one inch. This is your first harvest! The trimmings are delicious in dips, salads, sandwiches or as a garnish. After you cut them, the plants will naturally produce more tops. When the tops reach three inches again, mow them back to one inch. As long as the plants are indoors, cut them back whenever they grow to three inches. With short tops the plants can put more energy into developing healthy roots, and that will help them get a good start when you put them in the ground. A few weeks before planting, stop trimming them. Top growth will be important outside.
Harvesting Onions
By: the Editors of National Gardening
There's never a time when onions aren't ready for harvesting. They can be picked and eaten at any stage. No matter how many onions you use during the season, though, it's nice to have a crop of big onions mature at the end of summer to store for the fall and winter months.

When to Harvest

You can always tell when onions have stopped growing. The leaves will lose their color, weaken at the top of the bulb and flop over. Each year a few new gardeners watch the leaves die and wonder, "What's wrong?" There's nothing wrong; it's Nature's plan. The leaves' job is done - they've put the last of their energy into the bulbs.

Let most of your onion tops fall over by themselves - maybe 80% or 90% of them - then bend over the rest of the tops. Once they're down, leave the bulbs in the ground for another 10 days to two weeks to mature fully. It's not good to leave the onions in the ground for longer than two weeks after the tops die because they become open to organisms that can cause rot in storage, or they might even start growing again.

Pull your onions up on a sunny day if you can, then let them sit in the sun for another day or so to dry (in hot climates this usually takes just a few hours). This drying kills the root system at the bottom of each bulb. The roots will be like little brittle wires when they're dry.

Picking the right day to pull the onions can determine how well the onions will keep. If you harvest them after some rainy weather they'll have a lot more moisture in them and won't dry out as well.

Curing

After drying the onions in the open for a day or so, it's time to bring them under cover for a second, longer drying or "curing" process.

Some people cut the tops off the onions before curing, but that's not strictly necessary. However, if you do trim the top leaves, don't cut them any closer than one inch from the bulb. Otherwise the neck won't dry out, and the onion could rot in storage.

To cure the onions, spread them out in any warm, airy place out of the sun, such as on a porch. If you find you have too many onions for your available porch space, try spreading them out near the edge of your driveway, covering them with a light cotton (not plastic) sheet to provide shade. The sheet, held in place by stones along the edge, keeps the sun from burning the bulbs but still allows a lot of air circulation. Turn the bulbs a couple of times to promote even drying.

Heavy coverings like canvas or plastic trap moisture inside, so the onions will never get really dry. With the sheet system you won't have to worry about a few scattered rains. The sheets and the onions dry out rapidly together after a shower.

You don't want any wet spots on the onions when you put them in storage, so cure them really well. This can take two to three weeks. After curing them, hang the onions in mesh bags in your garage and dry them some more before putting them in your root cellar. It doesn't take this long in the South, but wherever you live, the longer you cure your onions, the better they'll keep.

Curing Basics

Here are the basics of curing:

* Sun dry for just a short time.

* Cure just the onions you'll store; separate the soft, young and thick-necked bulbs and use them first.

* Cure thoroughly in a warm, well-ventilated area away from direct sun.

* Don't crowd onions during curing; give them room to breathe.

* Onions are ready to store when the skins rattle and the roots are dry and wiry.

1 comment:

DJKJ said...

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