Onions, garlic, shallots and leeks are members of the lily family and belong to the genus Allium. Onion is an important commercial vegetable crop worldwide in addition to being widely grown by home gardeners. Garlic, shallots and leeks are often grown at home since they are sometimes hard to find in stores.
- Soil Preparation
Onion grows best in a loose, well drained, highly fertile soil which is well supplied with organic matter. Heavy, compact soils such as clay tend to restrain bulb development causing bulbs to be irregularly shaped and small.
Add sand and organic matter such as manure or compost to clay soils to improve draining and aeration.
The following steps may be used to prepare soil:
- Apply recommended amount of lime
- Apply three to four bushels of well rotted manure or similar material per 100 square feet
- Rototill everything into the soil
- Broadcast fertilizer evenly over the area and work into soil
Onions can be planted either as seeds, transplants or sets. When raising onion from seed, the spacing should be between 1½ to 2 inches apart and in rows 12 to 16 inches apart with the seed sown one-half-inch deep.
Transplants purchased from a reliable dealer are inexpensive and easy to handle. Purchase plants which are stocky, have bulbs the size of peas and have bushy roots.
Onions sets (immature bulblets) can be used for green onions during the rainy season or mature onions in late dry season. Plant onion sets three to four inches apart at a depth of one inch. Onion sets can be planted in early rainy season as soon as the ground can be worked.
- Lime and Fertilizer Application
Onions are sensitive to acidic soils and grow best when the soil pH is between 6.0 and 6.8. Strong acidic soils should be limed according to test results and it is most effective when mixed thoroughly with the soil.
Since the root systems of onion are very limited, high soil fertility is essential for good production.
Apply two to three pounds of 10-10-10 fertilizer per 100 square feet. Fertilizer should be broadcast evenly and worked into the top two to three inches of soil prior to seeding.
Gardeners may find it necessary to side-dress with fertilizer after one month. This is especially important on light sandy soils or it heavy rains leached nitrogen from the root zone. To side-dress, apply one pound of 10-10-10 fertilizer per 100 linear feet of row. For best results, work fertilizer into the row with a light cultivation and then water well.
To avoid burning roots, bands of fertilizer should be placed three to four inches away from the plant on each side.
Natural Fertilizers can also be very effective when the right choice is made from the many types available.
Water when dry periods occur. Onion require at least one inch of water per week. If water is needed, irrigate thoroughly early in the morning until the soil is moistened eight to ten inches deep.
If rainfall is deficient, it may be necessary to water once a week, or if you have sandy soils, two times per week.
- Weed Control
For best results, onion should be kept free of weeds. Cultivate shallowly when weeds are small to avoid damaging the plant root system.
A mulch material such as straw or compost applied after the plants are well established can conserve soil moisture, prevent soil compaction, and help suppress weed growth.
- Pests and Disease Control
The principal insect pests of onion are thrips and maggots. Common diseases include blast, downy mildew, neck rot and smut.
Appropriate measures should be taking in other to work in a pest free farm area.
nions can be harvested at any stage of development. Scallions can be pulled when only slightly swollen bases have formed. Green onions have a definite bulb formation and are harvested throughout the growing season.
Hilling the stems with soil once they reach a height of four inches will help green onions to have a longer, usable white stem.
Harvest onions for storage when the bulbs are matured and the tops are withered over. The best varieties for storage are grown from seed rather than sets or transplants.
Before storage, onions must be allowed to dry out for several weeks until the skins are papery, the necks are tight, and the roots are completely shriveled and dry.
This can be done by pulling the plants and spreading them out for drying. Thick-necked onions do not store well and should be used promptly.
If you are going to braid the onion tops, do it soon after digging while the tops are still relatively pliant. After braiding, hang the bulbs in a dry, well-ventilated place.
Instead of braiding, you can also cut the tops off one inch above the bulb after drying.
Store bulbs in crates or netted sacks in a cool, dry, well-ventilated space. A temperature around 35oF is ideal, but don’t let the onions freeze