June 16, 2023: Planting for winter harvests starts now

From Linda Gilkeson:

It hardly seems possible, but we are starting into the main planting season for vegetables that will be harvested over next winter. Crops for winter harvests must do their growing in the growing season, which means sowing them early enough that they have time to mature before the shorter, colder days of October put an end to growth. Ideally, in October your living refrigeration (the garden) will be bursting with maturing hardy vegetables—but it all depends on getting those seeds planted at the right time. You can print out a planting chart showing when to plant what veggies at: http://www.lindagilkeson.ca/pdf/Linda%20Gilkeson%20Planting%20Schedule.pdf (Stick the list on your fridge to help you remember to keep on planting over the summer).

The last two weeks of June is the main planting window for sowing seeds of winter broccoli, winter cauliflower, and cabbage varieties that take less than 80-90 days to mature (check the days-to-harvest information in variety descriptions). Sow them directly in the garden or start them in flats, whichever works for you. I find that so many critters attack Brassica family plants (birds, slugs, cabbage root maggot, caterpillars, etc.) that I usually start mine in flats so that I can bring them indoors to safety at night while they are small.

Overwintering varieties of broccoli and cauliflowers are hardy biennials and not the same as the annual varieties we sowed this spring for summer harvests. If you don’t already have seeds you may have a hard time finding them this year. It looks like winter broccoli has gone the way of winter cauliflower, from what was once a wide choice of varieties to just one or two still being carried by small, regional seed producers. In British Columbia, Salt Spring Seeds, Full Circle Seeds and the BC Eco Seed Co-op each list a purple sprouting winter broccoli, but West Coast Seeds, which used to carry several varieties, doesn’t have any this year. In Washington, Osborne Quality Seeds lists a couple of purple sprouting varieties. Thanks to a local BC seed grower, the excellent winter cauliflower variety ‘Galleon’, is available from the BC Eco-Seed Coop. West Coast Seeds has the winter cauliflower ‘Walcheren Winter’. Salt Spring Seeds has ‘Purple Cape’ (and some US seeds houses have it as well), which is an excellent and reliable purple cauliflower. Eagleridge Seeds carries ‘Nine Star’, an old variety of broccoli (or is it a cauliflower?) with many small white heads; it can live through several winters if there are no severe cold snaps.

If you are not growing your own seedlings, watch for starts of Brussels sprouts, cabbage, winter broccoli and winter cauliflower for sale at nurseries and garden centres later next month. I know that Chorus Frog Farm on Salt Spring, the Compost Education Centre in Victoria, Russell Nursery in Sidney and other will have starts as will others. I will provide a more complete list of sources and sale dates of winter starts in my July message so please let me know about suppliers in your area. Don’t bother buying summer varieties of broccoli and cauliflower (such as Snow Crown, Snowball, Romanesco, etc. ) for late summer planting. They just don’t work! I have railed about this for years but garden centres are still getting seedlings from wholesalers who don’t seem to know (or care?) that these varieties fail as overwintering plants. They either end up producing a small “button head” prematurely or are just killed by winter cold.

Early July is the next planting window for important winter crops. As all but recent subscribers already know, Carrot Day is July 1st at my house, when I sow a big bed of carrots for harvests until spring. Planting the first week of July gives the roots enough time to reach full size by October. In early July, you can also sow beets, rutabagas, kohlrabi, as well as endive and radicchio (a surprisingly hardly vegetable). Even if you planted Swiss chard or kales this spring, you may want to sow more seeds of these in early July to have additional overwintering plants. Hardy leafy greens can’t grow replacement leaves during the winter, therefore you need more plants to sustain winter picking than you do in the summer when they are actively growing.

Remember to shade the seed beds of these summer plantings to keep them evenly moist during germination. This is especially important for carrots and lettuce, which don’t germinate well in warm soil. Use anything to shade beds: burlap, old towels or sheets, plastic bags that held compost, etc… Check daily for germination and remove covers when the first green tips appear.

Beware cabbage root maggot! I visited a couple of gardens recently where all of the cabbage family plants were stunted and dying due to infestations of cabbage root maggots. See Linda Gilkeson | West Coast Gardening | West Coast Gardening: Natural Insect, Weed and Disease Control With the early heat wave we had in mid-May, the first generation of these flies would have developed more quickly than usual. The maggots are already becoming pupa, the next stage of development from which the second generation of adult flies will emerge soon. There are usually 2-3 generations over the summer with the numbers in each generation higher that the last. This year I expect we will have a full third generation in August and September. Given how widespread this pest of the Brassica family is, you should just assume they are out there and protect your plants accordingly.

The flies only lay their eggs where the stem of the host plant meets the soil. Barriers are very effective in preventing the flies from laying eggs, but must be installed before the flies find the plants. For small plants (radishes, leafy greens, Chinese cabbage, etc.) cover the seed beds with insect netting before the seeds germinate. In warm soil, seeds can germinate in a couple of days so cover beds as soon as you sow. For seedlings of broccoli, cabbage, cauliflower, Brussels sprouts, install a barrier around the stem at the time they are transplanted into the garden (don’t wait! the flies comes out at dusk and are very, very good at finding host plants). For large plants the barrier is only needed just around the stem where the flies want to lay their eggs.

Cut 15 cm/6 inch squares of flexible waterproof material, such as plastic compost bags, heavy waxed freezer paper, or similar material. Cut a slit to the centre from one side so that you can slide the slit around the stem and lay the square of material flat on the soil surface. Hold the slit shut with a pebble if necessary. You need as tight a fit as possible around the base of the seedling stem, which is why the material can’t be too stiff as you don’t want to bruise or break the stem. This barrier stays in place for the life of the plant; just mulch over the top of the barrier.

Special offer from BC Eco Seed Co-op continues! Readers of my mailing list can get a 30% discount on seed order until August 31, 2023 by putting in this code: “Linda30” when you order.

Republished with permission from Linda Gilkeson’s Gardening Tips. See Linda’s website to sign up for her newsletter, purchase books, access free presentations and identify pests and diseases which may affect West Coast gardens.

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