Growing Onions
Growing onions requires a just a bit of knowledge to be successful
Perhaps it is best to start with what onions really need to grow and how they develop before describing all the types of onions you might choose to grow. Onions do have a relatively long growing season, part of the critical development is for the top growth. The amount of growth and development achieved in the top growth will determine the size of the harvested onion bulb. The bulb itself will not begin to develop until the required day length is reached. So starting seed early indoors can improve harvest, or purchase plants or premium sets. Other than that onions must have full sun and consistently moist, but not wet, soil.
Bulbing onions can be short day, intermediate day or long day onions. As mentioned, the bulbs do not begin to form until they receive the required minimum daylight hours. Long day onions require 15 hours, intermediate requires 12 to 13 hours and short day onions require 9 to 10 hours. Amazingly, in the north we get the longest summer days during the growing season and the south has shorter days. In southern regions zone 7 or warmer, short day onions such as sweet Vidalia are planted in fall and bulbs begin to form in spring. In the north we typically grow the long day onions for storing. We can also grow mild short day onions like bunching onions or scallions but they will develop small sweet bulbs. But short day onions are best grown in the south where they will fully develop a bulb. Intermediate day or day neutral varieties can usually be pretty successful in any region.
Plant Onions Early
In the north and midwest we have to plant as early as possible so the plant has the chance to grow enough top leaves to start setting bulbs as soon as the days are long enough. Onions should be planted as early as you can work your soil, usually about four to six weeks before the last frost date for your region. If you plant late of course you will get pretty small onions.
Start Onion Seeds
If you are able to start seeds yourself in winter you will get the best results with your harvest. You can start any onions by seed so try a variety. Be sure to get your seeds started toward the end of February so you have good sized plants to transplant and produce large onion bulbs. If you plant your seeds in the ground, even very very early, it is unlikely they mature quickly enough to produce much if any bulb.
Buy Onion Plants
If you are not able or interested in started your own seeds it is best to purchase onion plants. If you buy from a local nursery they will have bee started from seed in a greenhouse and will give you good harvest results. If you buy locally the onions will generally be the best varieties for your region. If you order plants online be sure to select a reputable grower with good shipping habits. Just don’t ever buy an un-named variety that just say red, yellow or white onion from any source. Who knows what variety they are and if they grow well in your region.
Buy Onion Sets
Because onions are biennial, second year plants are available as onion “sets”. They grew in the previous growing season and in the second season, when made available as sets, their mission is to flower. The plant puts most of its’ energy into producing a flower to set seed rather than a good sized onion bulb for you. Onion sets are often what you see labeled just as red, yellow or white.
Caring for Onions
Once you get things figured out onions are pretty easy to grow. They resits most pests and problems. Make sure your soil is well loosened before planting and dig in organic matter such as compost. It is important to remember that onions are very shallow rooted, growing close to the soil surface. Be sure you water regularly to keep the soil moist but not wet. Onions also are adversely affected by competing weeds. Keep the onion bed free of weeds, cultivating carefully and shallow so as not to damage bulbs.
Growing onions requires a fair amount of nitrogen to encourage robust top growth. Apply a nitrogen fertilizer every couple of weeks. Once the bulb begins to form you can discontinue feeding.
Harvest Onions
When the onion bulbs are full size the top growth will become dry and fall right over. Stop watering completely so you can begin to harvest and dry the bulbs. If the weather is dry you can leave them in the ground for a few to several days. If your soil is good and loose and the bulb tops are largely exposed, you may be able to gently pull them out with a bit of help lifting with a garden fork. Otherwise, do not PULL the onions, gently lift them by carefully scooping under to loosen and expose the bulbs and remove them from the soil. Be very careful not to nick the bulbs. If you you do, the nicked onions should be refrigerated to be used first. The damaged bulbs don’t store well. Once harvested keep the onions in a warm dry place for a few weeks. When the outer skins are dry and the neck has tightened up they are ready for storage. If you do not cure long enough the onions will may decay in storage. Properly dried and stored your onions should last at least 3 to 6 months.
If you chose to grow a sweet variety for fresh eating follow the same guide for harvest and drying. But sweet fresh eating onions usually have a high water content and you will not be able to store them very long. Keep a limit on how many you plant and you should be able to consume them through the summer before you need your stored onions.
The onion tops will not necessarily all fall at once. You can leave them all in the ground if it is warm and dry until they do. Or you can start harvesting a few that are ready for fresh eating.
Storing Onions
Make sure your onions are all good and dry before storing. Too much moisture will rot the onions. Cut the top off an onion to see if any milky liquid seeps out. If it does, they need more curing time. One ready cut all the tops off, trip roots, and bag the onions in mesh bags. Always store your onions in a cool dry place. Never let them freeze, but if stored over 40 degrees they will begin to sprout.
Ready to give onions a try?