As summer winds down in many areas of the country, it is time to start planning for winter tunnel production. Whether you have a heated, climate-controlled greenhouse or an unheated tunnel, there are a variety of crops that do well for winter growing to extend your harvest season. If you live in a climate with consistent temperatures below freezing, many farmers grow in unheated tunnels with layers of row cover over the crops for extra protection. Take off the row cover every day when the sun is out and replace it later in the day. Heated tunnels are also an option for these climates. If you are in a milder region, many cool-season crops can be grown in unheated tunnels. It is important to plant early enough to ensure plants are established once temperatures go down and before the Persephone period, when growth drops to a slow pace; then plants will put on more growth as temperatures rise again later in the winter and spring. Make sure to have adequate airflow and minimal irrigation, be especially careful to avoid overhead irrigation to decrease disease.
Quick-growing greens, herbs, brassicas, and a variety of roots can be planted in late summer or fall into tunnels. These cool crops will be sweeter in the cooler months and will perform well in tunnels. We look for varieties that have great disease packages that are robust and fast-growing for winter production.
Lettuce: We are currently seeding our overwinter lettuce trials to see which lettuce varieties from our lineup perform best in unheated tunnels. Cegolaine is a favorite of ours from previous overwintered lettuce trials. It performs great against disease and sizes up well. It can be paired with Requena, a new mini-green romaine. For our Eazy leaf lettuce line, Buckley is a favorite for cooler fall and winter growing. Eztron is also a top performer for growing indoors in cooler months, as well as Burgandy, Brentwood, and Hampton.
Spinach: Sioux is a semi-savoy, fall-slotted variety that has a great downy mildew package and high yields. Banjo is one of our favorite year-round, semi-savoy types that does well for large leaf production. C2-606 is our smooth leaf, fall-slotted variety that is widely adapted and performs well indoors.
Radish: These are perfect for indoor greenhouse production because of their fast speed. Both Donato and Crunchy Royal are quick to bulk up to a nice bulb size and have great flavor.
Green Onions: Green banner is our faster variety, but can bolt later in the spring, so it is best suited for production earlier in the fall. Fukagawa is another early type that is very upright with a good disease package.
Pac Choi: Our green-stem varieties do well for extended season tunnel growing, specifically Li Ren, Mei Qing and Yoshi. These are compact, dense, and fast to mature.
Baby Greens: Fast-growing greens with sweet and slightly spicy flavor are great for winter greens mixes. We suggest trying Early Mizuna, Red Stem Mizuna, Terus Tatsoi, any mustard, and corn salad. Our hairless baby daikon leaves, Sai Sai green and purple are great for winter production as well. For arugula, check out Astro, Speedy, Surrey and Uber.