If you want to enjoy flavorful onions, garlic, and shallots next summer, the time to plant is now (in most zones). Many gardeners plant sets of each of these vegetables, because sets tend to have much higher success rates than seeds or transplants. Not only are they easier to grow, they also mature much more quickly than seeds. Below are the ins and outs of planting and growing onion, garlic, and shallot sets.
When Should You Plant Sets?
When to plant depends on what you plant. Although you may be able to plant onion sets in the spring (preferably in March or April when you’re sure the temperature won’t dip below 20 degrees Fahrenheit), it’s often best to plant them in the fall. To prevent rot, be sure to plant them in raised beds or raised rows about four inches high, in loose, well-drained soil, and in a spot where you haven’t grown onions or other alliums for the past two years. This will give the onions the room they need to form large bulbs. Augment your soil ahead of time with nitrogen using either finished manure or nitrogen fertilizer. Plant the onion sets about an inch down into the soil, and fertilize every other week until the bulbs begin to separate themselves from the ground (this may occur in the late spring). You'll also want to water your sets once a week, or more often if you're aiming for sweeter onions.
In the spring, you may notice some of your onions starting to flower. Cut the flower stalks off right away, as they're signs of bolting. These onions are finished growing and won’t grow any larger. Pull them and start the curing process. As for the rest, harvest them when their top greenery begins to turn yellow and fall over.
Garlic can also be planted in the spring or as soon as the ground can be worked again. If you live in a place with a mild climate, planting in the spring might even be best. Everyone else will want to get garlic in the ground in the fall to improve its flavor. If your area gets a hard frost, plant about six to eight weeks before the first one hits.
A few days before you plan to plant your garlic (ideally about a month before the first frost of the year), you should break the cloves apart. As with onions, you'll want to plant garlic in well-drained soil to prevent rot, placing the bulbs four to six inches apart and about two inches deep. Make sure the sharp end of each clove is pointing up. When the green shoots start to grow in the winter and spring, cut them to encourage larger bulbs. Use the scapes to add a kick to your cooking.
Shallots tend to be very responsive to day length, meaning they'll adapt to the area they’ve been planted in. If you’re planting in zones five through nine, it’s best to plant your shallots after the first frost of the fall. Plant them about six inches apart and two inches deep. Some exposure to light freezing temperatures will help improve their flavor. However, if you’re planting in zone 4 or lower, you may want to wait until the spring to plant your sets, or at least until the ground thaws enough to work the soil. Shallots can handle some frost, but extreme freezing temperatures can negatively impact their growth. As with onions and garlic, shallots prefer well-drained soil.
Tips to Keep in Mind When You’re Planting
If You Can’t Plant Right Away…
Many seed companies include instructions with your onion, garlic, and shallot sets that often say they must be planted as soon as possible. If you can’t get around to it for a while, keep your sets in a cool, dry place like a storage shed, garage, or basement until you can plant them.
If You Live in a Very Cold Area…
Northern climates experience freezing temperatures. If waiting until spring to plant isn’t an option for you, be sure to mulch your sets with straw to provide them with some insulation while they’re in the ground. Remove the mulch in the spring when the threat of frost has passed.
Fertilize your sets with nitrogen, either in the form of finished manure or nitrogen fertilizer. This will help them grow larger. Water them well every three to five days while the bulbs are forming.
Bulbs, especially shallots, can easily rot during an especially wet winter. It helps to create ridges around your plants to drain the water away from them during heavy rains.
Weed, Weed, Weed…
Although you may not have to worry about weeding until spring, you'll want to be sure to pull any weeds you see as soon as you notice them. Weeds inhibit the growth of onions, garlic, and shallots, so pull them early before they become a real nuisance!
Keep Gophers and Other Pests at Bay
Unfortunately, weeds aren’t the only annoyance you’ll have to deal with. You may also have to contend with bugs and rodents. Keep the tiny bugs known as thrips away from your onions by using insecticidal soap on them as soon as you see them. Onion maggots also lay eggs at the base of the plants, so do your best to keep mulch away from the onion’s roots, especially if you're expecting a lot of rain.
Although garlic is a natural pest repellent, you may have to be careful of white rot, which is a fungus that garlic is particularly susceptible to in cooler weather. Rotating your crops (e.g. don’t grow garlic in that spot for three years) and removing debris after harvesting them will help keep this fungus at bay.
Keep pests like worms away from your shallots by dusting wood ashes around them a few times during the winter. You should also put up netting in the spring to keep bugs and vermin from feasting on them.