Fall in the garden is often thought of as a time for harvesting and putting it to bed for winter. In areas where temperatures during the winter get below freezing, you might think you can’t grow anything in the winter months. This is only partly true—you won’t be able to harvest anything in the coldest months, but you likely can plant some crops in fall that can be harvested in springtime. Here’s what you need to know for a successful early spring harvest.
The best timing for a fall garden
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When you’re considering the timing of your fall garden, you will want to aim for a period where the temperature is around 50 to 60°F. It’s good for the weather to be cooler, but you don’t want to put your plants in the ground if temperatures are below freezing for more than a night.
Alliums like onions, garlic, and shallots can be planted in fall and will produce next year during the summer. These plants take awhile to mature and can survive over the winter with just their root system. Since they don’t sprout until spring, you should make sure to label your plants carefully so you don’t accidentally plant something else on top of them. For these plants, use mulch to suppress weeds and make sure the soil is well-fertilized with bone meal or bulb fertilizer to pave the way for a good harvest next year.
Onions are one of the longest-to-harvest root crops, maturing over the course of about nine or 10 months. They are also perennials, like all alliums, so they will continue to produce as long as you want them to. Onions are planted with what is known as “sets”, or smaller bulbs that were grown the previous season. This gives them a head start on the growing season and makes them more resilient in colder conditions. You will be able to tell when they’re ready to harvest by seeing the base of the greens where the bulbs turn yellow or darker, depending on the type of onion.
Leeks can be planted as seeds in fall and will sprout in spring. They should be spaced about six inches apart from each other. Although leeks aren’t planted from bulbs, they still need about four to six inches of mulch to overwinter successfully. The seeds should be planted around the same time you plant onion sets for your area, and leek plants will be ready to harvest after about six or seven months in the ground. The diameter of a mature leek will be between three quarters and an inch and a half in diameter at the base.
Garlic is similar to onions except that it will begin to whiten at the base of the greens when it’s ready to harvest. Since garlic grows in clusters, you can separate the cloves and plant them just like a flower bulb, with the root end down and the papery pointed end up. You can buy garlic sets or you can use cloves from your previous year’s harvest. Garlic bulbs can be harvested in summer, but many varieties will also begin producing greens or scapes that can be harvested in spring.
For a quicker harvest, you can try growing shallots. They clump like garlic, but are layered more like onions and are often thought of as a cross between the two. Shallots will be ready in early to late spring, depending on when you plant them and how long your cold season is. You will know they’re ready to come out of the ground when the base of the greens begins to darken.
If you just can’t wait for bulbs to be harvested and cured, you can plant some bunching onions for the earliest of spring harvests. These onions are usually grown for their greens although there’s no rule against eating the bulbs, and you can harvest them as soon as the greens are about a half inch in diameter or about six inches tall.