The Winter Greens Trifecta: Kale, Collards and Spinach

 

Here are three types of winter-hardy leafy greens to feed you through the winter. In central Virginia, it is too late to sow any greens for this winter. If you live in zone 9 or warmer, where you could still sow spinach and maybe collards and kale in December. Spinach sowings can be made until Oct 15 in South Carolina and Nov 15 in Louisiana. This post is to help with planning for next year.

Kale Varieties

There are two main types of kale, Brassica oleracea and Brassica napus. Oleracea types can have more cold tolerance and go somewhat dormant in cold weather, which lets the kale survive to regrow when the weather improves in the spring. Our outdoor kale, for both fall and spring planting, is Vates Dwarf Blue Scotch Curled, an oleracea type, the most cold-tolerant we have found. We prefer the curly-leafed kind over the flat-leafed as it holds up better against wilting and wind damage. We have not been successful indoors or out with dinosaur kales (also oleracea) as they harbor too many aphids in the curled-back edges of the leaves.

The napus types continue to grow at lower temperatures than oleaceae do, but they can’t stand such cold temperatures. The special spring kale varieties such as Hanover Salad, and the Russian and Siberian kales, are all napus types. White Russian and Red Russian kales do very well in our winter hoophouse but do not survive our winters outdoors. They are more productive and better flavored in our winter hoophouse than Vates.

Collard varieties

Collards have risen in popularity in recent years, partly thanks to the book Collards: A Southern Tradition from Seed to Table by Ed Davis and John Morgan, two geographers who traveled the South gathering information, stories, and seeds from collard growers both black and white. Their seed collection inspired the Heirloom Collard Project to preserve some Southern foodways. Seed Savers Exchange, Ujamaa Seeds and Southern Exposure Seed Exchange have been growing sixty varieties to preserve the genetic diversity of collards and increase the availability of seeds.

Our long-time favorite collards are Morris Heading, with slightly savoyed leaves, finishing with a head later in spring. More recently, we have been enchanted by some with beautiful colors, such as Alabama Blue and Nancy Malone Wheat Purple Collards. We’ve also grown Georgia. Northerners seem to prefer smaller-leafed collard varieties such as Champion, Flash, and Top Bunch. Green Glaze and Big Daddy Greasy Green collards have shiny leaves more resistant to caterpillar attacks.

Spinach varieties

For people who love OP vegetables, the Bloomsdale varieties —Abundant, Winter, and Long-Standing —are reliable. However, for bolt-resistance and productivity, we go with the hybrids. On the East Coast, bubbly savoyed spinach varieties are preferred, while on the West Coast, smooth-leaved ones are popular. We experimented with smooth-leaved spinach, thinking it would be easier to clean, and it probably is. The disadvantage is that it wilts very quickly after harvest and needs to be picked and chilled promptly. Space is a good smooth-leaved variety.

For a dark-leaved savoy type, with good cold tolerance and good bolt resistance, we compared Acadia, Avon, Escalade and Reflect. Acadia (45d) and Escalade (43d) had the best early fall harvests and best bolt resistance in our trial of overwintering. They are both rated highly for baby leaf production, if that’s what you do. Spinach is cold tolerant down to 10°F (–12°C).

Sowing

Brassicas germinate very well at high temperatures: the ideal is 77°F–85°F (25°C–30°C), and 95°F (35°C) is still OK. Given enough water, the seedlings will emerge in 4.5 days at the low end of this range, and at the top in only 3 days. The third week of June is a good time to start sowing fall brassicas in our region. We use an outdoor nursery seedbed and bare-root transplants for brassicas. https://www.sustainablemarketfarming.com/2017/01/10/bare-root-transplants/

For the seedbeds, we use insect netting (ProtekNet) on wire hoops—good airflow is vital. If you use flats, it can help to have them on benches in an enclosed shadehouse, or outdoors, above the 3′ (1 m) height flea beetles can jump.

Spinach needs much cooler conditions, and we wait till September and direct sow. Eight weeks before the first fall frost date is a good time to start planting spinach again, if it’s not too hot.  Spinach comes up quickest at 59°F–86°F (15°C–30°C). It makes up for lost time by maturing in just 50 days from sowing. The flavor of spinach is sweetest and nuttiest once the weather cools. Unless overcrowded (by other spinach or by weeds), or underwatered, spinach will not bolt until spring daylight reaches 14 hours.

Our second fall sowing is usually September 20–30, and these overwinter small and do not reach harvestable size until early spring. This planting will bolt in the spring at a date between the first fall sowing and the spring sowings. In climates colder than Zone 7, make the fall sowings earlier in order to have adequate growth before hard freezes, sowing as soon as soil temperatures are cool enough for germination, perhaps 77°F (25°C).

Amounts to grow for overwintering

We transplant our dwarf kale at 12″ (30 cm) apart, 4 rows in a 4′ (1.2 m) bed. We plant collards at 18″ (46 cm) in-row spacing. For a hundred enthusiastic vegetable eaters, in spring we grow 1,080′ (330 m) of kale, and 540′ (165 m) of collards. We harvest kale and collards by the leaf, for multiple harvests.

We typically plant 5 rows of spinach on our 4′ (1.2 m)-wide raised beds, and sow 1,080′ (330 m) to feed 100 people all winter (the same amount as we sow of kale). We always grow collards, kale, and spinach in raised beds. We grow spinach on 6″ (15 cm) spacing in-row.

Transplanting

We aim to transplant most brassicas at four true leaves (3–4 weeks after sowing). It is better to transplant crops at a younger age in hot weather than you would in spring because larger plants can wilt from high transpiration losses. If it is necessary to use older plants to fill gaps, we pinch off a few of the lower leaves to reduce their water needs.

We plant fall kale by a mixed direct sow/transplant method that allows for the possibility of patchy germination, and requires less watering than if we direct sowed it all, and less time than transplanting them all. We sow 2 beds on each of three dates in August, with 4 rows 10″ (25 cm) apart. Later we carefully thin them, leaving one plant every foot (30 cm). We use the carefully dug thinnings from those beds to fill gaps and to plant more beds, at the same spacing.

Crop care

We do not normally rowcover winter kale and collards, as they will survive without. In harsh winters, we lose the collards. Using rowcover would keep crops in better condition later into the winter, but we have found the fibers stuck in the curly-leaved kale. In areas where continuous snow cover doesn’t happen, rowcover on hoops will protect spinach. If you use rowcover without hoops, the abrasion of the fabric on the leaves causes damage, and they are more likely to freeze to the fabric if you have wet weather followed by freezing nights. Hoops help create a nice microclimate, noticeable when you harvest.

Pest control

Use rowcover or netting to keep pests off the plants while they are small. Pests are less of a problem in winter. We are also lucky enough to have the naturally occurring wasp parasite of cabbage worms, the Braconid wasp Cotesia species, which are found as small cottony white or yellowish oval cocoons in groups on brassica leaves. If you find Cotesia cocoons, you can leave them in the field over winter. Or you could collect leaves with cocoons in late fall and store them at 32°F–34°F (0°C–1°C) until spring. Hopefully no one will clean out your fridge without asking.

Diseases

Details for dealing with several diseases and a chart of commercially available compounds can be found in Organic Production and IPM Guide for Cole Crops, by Abby Seaman, NYS IPM Program, and in the ATTRA publication, Cole Crops and Other Brassicas: Organic Production, by M. Guerena.

Harvest

We usually have about 7 beds each of overwinter kale and spinach and can pick one each day in October, November, February, and March. All three greens will make some growth whenever the temperature is above about 40°F (5°C), so we can also make occasional harvests in December and January. Kale, collards and spinach last until they bolt in early May, sometimes April for spinach.

We use a marker flag to show which bed to harvest next, moving it to the next bed after each harvest. We harvest kale and collards by snapping off the largest leaves. There are three main ways to harvest spinach:

1. Harvest by the leaf, with scissors. This has the advantage of producing an attractive product —all whole leaves. I believe it is also the least damaging to the plant and likely to give the highest total yield over the life of the plant. It can be rather slow, depending on the skill of the harvester.
2. The buzz-cut method is much faster, and the plants live to carry on producing more. Gather the leaves and cut them all 1″ (2.5 cm) above the crown. The plants do take longer to recover from buzz-cutting than from leaf harvesting. If you are making a salad mix, the fact that the leaves are cut might not matter. This is a good method when time is at a premium. If your plants are frost damaged, with yellow-white patches, this method might not work as well as leaf-harvesting as you might have to do lots of sorting.
3. The final method is the single harvest: cut the plants, then till in the crop residue and start again. This is the quickest method and produces the most beautiful spinach, but obviously it isn’t suitable if you hope to overwinter your spinach as it kills the goose that lays the golden eggs, and it will be too late in the year to resow. Season extension into winter relies on extending the harvest period by keeping plants alive and productive for multiple harvests.

More information

Workhorse Crops for April includes the links to each month’s post in that series (lots of kale)

Success with winter kale and collards earlier this year covered crop requirements, rotations, systems for growing these crops, timing, planning, sowing, transplanting, crop care and harvest.

Success with Spinach for Fall, Winter and Spring includes info on varieties. presprouting, floating Speedling flats of spinach on water in the daytime, and growing bare-root transplants.

Sowing kale, finishing planting cabbage, more on zipper spidershas info about kale varieties.

Planting kale, catching up on weeding and reading

Sowing beets, radishes and kale, transplanting cabbage.