1. Q: How deep should my onion transplants be set?
A: When transplanting, the onion plants should be placed approximately 1 inch deep or at least deep enough to support the plant and keep it from falling over.
2. Q: Is it necessary to remove the garden soil from around my onion bulbs in the spring to make large bulbs?
A: Absolutely not. Bulbing of onions is controlled by variety, temperatures and length of day. The onion will bulb when the required conditions are met. Removing soil around the base of the plant will not increase bulbing, although it appears to because the bulbs are visible. This operation may do more damage than good, especially to white varieties of onions. Removing the soil from around white onions results in sunburning which turns the top of the bulbs green.
3. Q: What varieties of green onions grow well?
A: The term green onion describes an immature onion. Even the large bulb onions such as Grano or Granex can be harvested immature and used as green onions. Some gardeners who seed these varieties of onions directly in their garden selectively thin them as they grow and use the thinnings as green onions. Evergreen Bunching and Beltsville Bunching varieties will not form bulbs but produce clusters of 4 to 8 slender, white onion stalks. The shallot, a multiplier-type onion with a distinct flavor, is also used as a green onion.
4. Q: What is the difference between a set and a transplant?
A: Although many gardeners use these terms interchangeably, there is a difference. An onion set is a small bulb, to 1 inch in diameter. It is produced under conditions which rapidly produce a small bulb which, when planted, will grow a larger bulb. An onion transplant is a plant between 8 to 10 weeks old which has not gone through the bulbing process, and if planted at the right time will produce large bulbs.
5. Q: What is a bunching onion?
A: Several types of onions are used as green bunching onions. Evergreen White Bunching and Japanese Bunching are frequently planted varieties of this type. They may be planted from seed, sets or transplants. Bunching onions are generally classed as multipliers because they propagate themselves. They are cold resistant and can be grown during winter. They will not bulb and are harvested as needed, using both the root and the tops.
6. Q: What is a shallot?
A: A shallot is a member of the onion family which lives for many years and is grown for its mile, garlic-flavored roots, made up of segments called cloves. The plants will grow to be about 18 inches tall and often bear white or violet flowers in early summer.
7. Q: Every year I buy onion plants to be set out in the spring in my garden. Some years they make nice size bulbs and other years they don't. Why?
A: There is no simple answer to this commonly-asked question. First of all, obtain varieties which will bulb in your particular area. Always buy plants about the size of a lead pencil. Larger plants will not produce earlier or produce larger bulbs. Generally, a large onion plant will produce a seed stalk after planting instead of forming a large bulb. Always set the plants in your garden at the right time for your area.
8. Q: Should I break over the tops of my onion plants to get a larger bulb?
A: Breaking over the tops of onion plants will not increase bulb size but can prevent bulb enlargement. Onion bulbs increase in size as sugars manufactured in the top are translocated to the bulb. If the tops are broken, this process stops preventing further bulb enlargement. This question comes up often among gardeners interested in growing large onions.
9. Q: What is the difference between green onions and leeks?
A: A leek has a much milder flavor than an onion. The term scallion describes leeks and green onions.
10. Q: What varieties of onions should I plant to produce the large, sweet bulbs?
A: Plant the varieties 1015Y, Grano, Granex or, if you prefer the red onion, Burgundy. These "Bermuda" onions are considered short-day onions. Planted at the right time for your area and given proper moisture and fertility, they should produce large, sweet bulbs like those you find in the spring at local grocery stores.
11. Q: What causes my bulb onions to send up flower stalks?
A: Flowering of onions can be caused by several things, usually temperature fluctuation. An onion is classed as a biennial which means it usually takes two years to go from seed to seed. However, this condition is triggered by temperatures. If an onion plant is exposed to alternating cold and warm temperatures resulting in the onion plant going dormant, resuming growth, going dormant and then resuming growth again, the onion bulbs prematurely flower or bolt. Flowering can be controlled by planting the right variety at the right time. Use only transplants that are pencil-sized or smaller in diameter.
12. Q: Should I remove the flower stalks from my onion plants?
A: No. Once the onion plant has bolted, or sent up a flower stalk, there is nothing you can do to eliminate this problem. The onion bulbs still will be edible but probably will be smaller. Use these onions as soon as possible because the green flower stalk which emerges through the center of the bulb will make storage almost impossible.
13. Q: After harvesting, what is the best way for me to store my onions?
A: Onions should be stored in a relatively cool, dry place. Sweet onions will not store as long as more pungent varieties. Maximum length of storage of sweet onions will run from 2 to 3 months. Allow your onions to fully mature in the garden before harvesting. Maturity is indicated by the fall of the top of the onion plant. After the tops have fallen, pull and dry the onions in the garden for several days. Some gardeners prefer to pull the onions up partially which allows the onions to dry while still in the ground. After drying, remove the roots and the top, leaving about 3/4 to 1 inch of the neck to seal and prevent entrance of decay organisms.
14. Q: The foliage on my onion plants has purple spots which kill the leaves.
A: The purple spot is caused by a fungus, and the disease is purple blotch. The fungus is airborne and infects onions during extended periods of dews and intermittent rain. The loss of foliage from infection by this fungus can result in small bulbs and secondary rots which prevent the bulbs from storing properly. Purple blotch is controlled with fungicides. They should be applied at 10- to 14-day intervals as long as weather conditions favor disease development.
15. Q: The tips of my onion leaves turn brown and have gradual die back of the leaves down to the bulb.
A: This is a foliage disease known as tip die back of onions. It is suspected to be caused by the fungus Alternaria. It is commonly associated with plants that are not growing properly. Pink root can also cause a weakening condition of the plant which continues die back of the leaves. Some varieties such as the 1015Y are more resistant to diseases than others. The total cultural picture should be considered when tip die back becomes a problem.
16. Q: My onion plants are stunted and not growing properly. When I remove them from the soil, I find that the root system is deteriorating and has a purple to pink appearance.
A: This is pink root of onions. If is a soilborne fungus that is most often found in sandy, cool, wet soils. There is no control for the disease other than rotation. When buying onion transplants, look at the transplants closely for pink roots on the young plants. If a large percentage of the plants have pink root, they should be returned to the store. Most onion transplants are certified free of pink root. Buy only those plants that carry this certification. Also use varieties resistant to pink root such as Grano PRR and Granex PRR.
17. Q: Why do my onions always rot when I harvest them and try to store?
A: In most cases, onions decay in storage as a result of neck rot. This is caused by a soilborne fungus. When harvesting onions, wait until the tops begin to dry and fall over. Once this has happened, lift the plants and allow them to dry. After the drying, clip the tops and dry the cut area for 1 to 2 days. By doing this, the cut tissue will dry, eliminating a possible site for infection. Then place the onions in a well-ventilated area and in a container that allows free movement of air around the onions. If the onions are to be stored a good fungicide program during the growing season is important to prevent diseases such as tip blight and purple blotch from entering the bulbs.
18. Q: My onion leaves look silver and some are dying. What causes this?
A: You could have thrips feeding on the leaves. Examine the plants for small yellowish or blackish insects. If they are present, treat with malathion or diazinon. Use as directed on the label.
19.Q: I am looking for a company to order an onion called Grano 502 from. Do you know of one?
A: You probably can can get transplants from Dixondale Farms, P. O. Box 127, Carrizo Springs, TX 78834. Phone: 830-876-2430.
20. Q: I'm growing onions in a container. The onions took off like crazy in the beginning. Then, the green stalks became limp and very little growth has taken place. What's wrong?
A: I think your onions have matured! Once they reach maturity, they begin to senesce and the tops yellow and fall over. Pull them up and dry them a week to 10 days before storing in a cool dry place.
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