Planting Brassica Seedlings for Fall

August 18, 2023

Now that it's mid-August, it's the perfect time to plant some fall brassicas - broccoli, cabbage, cauliflower, kale, and Brussels Sprouts. The end-of-season cold weather will sweeten them up and make for a great harvest.

A few weeks ago, my head gardener, Ryan McCallister, started several trays of seeds for our autumn crop. When planting brassicas, it is important to plant seedlings rather than seeds so they have time to become established before any drastic temperature fluctuations. Yesterday, the plants were big enough and strong enough to put into the ground. And then it's just six to eight weeks before we're picking fresh fall greens once again.

Here are some photos.

: We start many of our vegetables from seed inside my greenhouse where they can be nurtured until they are ready to transplant. If you follow this blog regularly, you may recall Ryan started these trays just weeks ago.

: The trays are kept inside our Urban Cultivator until they germinate, and then they are brought out into the main greenhouse to grow some more.

: It doesn’t take long, but now they’re ready to get into the ground.

: First, the beds are cleared of any organic debris left over from the last crop. For fall planting, as soon as early-season plants have passed their prime and appear close to bolting, they can be pulled out and the area can be replanted with a different crop. Rotating crops will help avoid diseases particular to one plant type and balance nutrients in the soil.

: In this bed, Ryan measures the area for cabbage. The cabbage seedlings should be spaced at least 12 to 18 inches apart in the row…

: … and then those rows should be two to three feet apart. Proper measuring will ensure the vegetables have enough room to grow. Our cabbages have been so beautiful and large in this new garden.

: Cabbage seedlings have roundish leaves with very small teeth. As they grow, they get a thick center stem and then the green or purple cabbages in the center.

: Ryan gently removes each seedling out of the tray. Seedlings should be about two to three inches high before transplanting, and after the seedling has its two “true leaves.” True leaves are the leaves that grow after the initial seed’s cotyledon leaves appear.

: Ryan is using a stainless steel widger from Johnny’s Selected Seeds. This is one of our favorite tools for working with small plants. The unique convex stainless steel blade is ideal for delicately separating seedlings and transplanting.

: The seedling should be planted at the same depth it was grown in the tray. Ryan scoops a handful of dirt to make a hole.

: And then gently places the seedling into the soil.

: As with every plant, Ryan then tamps down on the surrounding soil carefully to make sure there is good contact.

: Here is the bed all planted – it won’t take long before these grow. They will be watered and checked every day. We still have a lot of summer vegetables growing, so there is always something to harvest during the season.

: This is a tray of Brussels sprouts. Like most vegetables, Brussels sprouts need a minimum of six hours of sunlight daily. They also like fertile, well-drained, moist soils with plenty of organic matter.

: Ryan looks through the tray and thins the seedlings. He selects only the strongest, healthiest, and most compact plants.

: And then using the same widger, Ryan removes the plants from the tray and places them where they will be planted in the garden bed.

: Brussels sprouts need room to spread out, so Ryan places them 18 to 24 inches apart also with two to three feet in between rows.

: And then just like the cabbages, he plants the Brussels sprouts as deep as they were in the tray and then tamps down lightly around the plants. These require a fairly long growing season, about 80 to 100 days to harvest.

: The leaves are similar to broccoli and cauliflower, but more circular in shape and grow in whorls. Once developed, the plants will be upright with a single stalk thickly set with small, firm, cabbage-like heads.