Get ready for frost
For some of you, the first frost is fast approaching. If you'd like to buy time to extend your harvest season, be prepared for the autumn ritual of pulling row cover over your plants. Here's some advice on how to make it easier.
Row cover is available in different weights, which determines the amount of frost protection it provides. Heavier weights provide more protection, but also cost more. So figure out how low the temperature is likely to go before you can get your crop harvested, and purchase the appropriate weight.
If your fall crops are grouped into a single area, consider buying one big piece of row cover that you can pull over multiple beds. It's available in sizes as large as 50' x 1,000'. Be sure to anchor it carefully so the wind can't get underneath and carry it away like a big kite.
For light frosts and low-growing plants such as spinach and lettuce, you can lay the row cover directly on the plants. Heavy frosts, however, can freeze plants where they touch the row cover; to prevent this, put hoops over the crops to hold the row cover above them.
Upright plants can have their growing tips damaged by abrasion of the row cover. Suspend the row cover above those plants with hoops or posts.
Spreading row cover is best accomplished with at least two people. While one person unrolls or unfolds the row cover and lays it on the crop, the second person should be following with weights to hold the edges down.
Row cover will last many years if handled carefully. As soon as your crop is finished, roll the row cover back up and put it in a barn or other building. If you worry that mice will get into it during the winter (they love to nest in it!), put it in a bag and suspend it from the building's rafters.
With the proliferation of hoophouses and low tunnels on farms, many growers are trying a new strategy to extend the season: planting seeds in fall to get the earliest possible harvest in spring. Southern growers and others with mild winters routinely use this strategy with many cool-weather vegetables. In the North, Quick Hoops™ with row cover and greenhouse poly moderate the cold and allow for successful overwintering. Spinach is often produced by fall seeding, resulting in harvest a month before spring-seeded crops. Many other crops are good candidates for overwintering, though there are few definite guidelines yet, especially given the wide variations in temperatures that are possible from one location to another. Here are some results of other growers' trials that may help inform your own efforts to get extra-early spring veggies.
At Johnny's Research Farm in Albion, Maine, we conducted overwintering trials under Quick Hoops™ last year. Spinach was direct seeded in early October; it germinated but stayed dormant until March and was ready for harvest around April 1. The flavor was remarkably sweet. Mache was direct seeded and it grew very well during the fall but bolted quickly when the weather started to warm up. This crop should be harvested either during the winter or very quickly in spring. Lettuce was seeded in mid September and transplanted to the Quick Hoops™ in mid October. Heads were harvested the beginning of April and, again, the flavor was good with no bitterness.
Eliot Coleman writes in his book -- "The Winter Harvest Handbook" -- about his ongoing experiments with seeding or planting in fall in Quick Hoops™. Spinach and lettuce direct seeded or transplanted in fall are ready a month earlier than spring transplanted lettuce. Overwintering scallions are ready five weeks ahead of spring-planted scallions. In considering other crops to overwinter, Coleman writes "we are just beginning to tease out the possibilities." Arugula, beets, carrots, and peas will germinate in February or March in the hoophouse, so why not in the field in Quick Hoops™? He intends to continue to trial crops and varieties to find the best timing for fall seeding or transplanting.
In the southern half of the United States, fall is the best time to plant hardy annuals that will bloom next spring. Some of the best hardy annuals used as cut flowers include agrostemma, bachelor buttons, bupleurum, larkspur, and nigella. Any other flowers that normally self-seed in your garden are also good candidates for fall seeding. Some will germinate in fall, grow into small plants, and then go dormant. Others won't germinate this year, but will sit in the soil until the chilling requirement is fulfilled and the weather warms. Larkspur is a good example of a cut flower that is much stronger and taller when direct seeded in fall.
The area where larkspur should be fall seeded is generally Zone 5b and warmer, except in parts of the Pacific Northwest where fall seeding is not advised because rainy winters may cause seeds to rot. Larkspur seed needs 14-21 days of soil temperature below 55˚F (13˚C) to germinate. Once the seeds germinate, the seedlings will grow through the fall and form small rosettes of lacy leaves. The plants will remain green until the coldest weather of winter, when they will start to look bleached out and dead. They will just be dormant, though, and will green up and start to grow again as soon as the coldest weather is past.
Larkspur seed can be planted with a precision seeder or by hand at a rate of .3 oz. per 100' of row. The seed should be covered completely because darkness aids germination, and watered in well if the weather has been dry. The rows should be clearly marked because the beds will need to be hoed once or twice before spring. Cool-weather weeds such as henbit can choke out a bed of emerging larkspur if not controlled.
The best flowers result when the plants have experienced six weeks of temperatures below 55˚F (13˚C). By planting in fall, growers with mild winters are more likely to capture the amount of chilling required.
In the North, however, longer, cooler springs allow for adequate chilling when the seeds are planted in spring. Larkspur can be direct-seeded as soon as the ground can be worked. Or it can be started from transplants, after the seed is chilled for several weeks in a refrigerator, and grown at 55˚F (13˚C).
Seed garlic from Johnny's is shipped in October so that you can plant it at the best time for your climate. The goal is to get good root growth to anchor the bulbs before winter, but no top growth. Depending on when the ground freezes in your area, it can be planted from the first frost through November. Until you're ready to plant, store it in a cool, dry place, 50-70F (not in the refrigerator).
Garlic is a heavy feeder and will produce the biggest bulbs when the soil has adequate nutrients. Compost is best, as it provides fertility, improves soil organic matter, and increases drainage. Garlic does not compete well with weeds, so prepare your beds, allow weed seeds to germinate and then cultivate shallowly to make a clean seed bed without disturbing new weed seeds.
Separate the cloves from the bulb and plant them 6" apart, with about 2" of soil on top. As soon as the soil freezes, mulch the bed with 4-6" of hay, straw, or grass clippings to prevent the bulbs from heaving.
For more information about growing garlic, see our Tech Sheet.