Start seeds indoors
Keep the top half-inch of seed-starting mix consistently moist; do not let it dry out or crust before sprouts emerge. Seedlings emerge in 5–10 days in warm soil.
A cool-season crop that produces dense green heads in spring or fall and rewards attentive timing with weeks of side-shoot harvests after the main head is cut.
Brassica oleracea var. italica · also called Calabrese, heading broccoli
Windows are counted from the average date of your last spring frost.
Home-grown broccoli can be harvested at peak density before the florets begin to open, a quality rarely available in supermarket produce. A single planting yields both a central head and a prolonged flush of smaller side shoots, extending the harvest window considerably.
A little history. Broccoli is a cultivated form of wild cabbage native to the eastern Mediterranean, selected over centuries for its enlarged, edible flowering head. It is the same species as cabbage, cauliflower, and kale, differing only in the part that was selectively enlarged.
Keep the top half-inch of seed-starting mix consistently moist; do not let it dry out or crust before sprouts emerge. Seedlings emerge in 5–10 days in warm soil.
Beds strongly preferred; containers work only with deep, large pots — roots need at least 12 inches of depth and the plant is top-heavy. In containers: 15-gallon pot, minimum 14 inches deep. Space plants 18 inches (45 cm) apart.
Water deeply 2–3 times per week; increase frequency during head formation. Water when the top inch of soil feels dry to the touch. Aim for about 1–1.5 inches per week including rain.
Side-dress (scatter fertilizer along the row and water in) once at transplant, again when heads begin to form. What to use: balanced 5–5-5 organic or compost-enriched amendment; avoid high nitrogen once heads form.
No pinching needed. After cutting the central head, leave the plant in place — side shoots (smaller secondary heads arising from leaf axils) will develop over the following 4–6 weeks and are harvested the same way.
It's ready when cut when the central head is firm and tight, florets are deep green and still closed, and the head measures 4–8 inches across — do not wait for any yellowing or loosening of florets. Cut the main stem cleanly with a sharp knife 5–6 inches below the head. Leave the plant rooted; side shoots will follow. Harvest side shoots when each small head is tight and 2–3 inches across.
Refrigerate unwashed heads in a loose plastic bag for up to 5 days. For longer storage, blanch florets for 3 minutes, cool in ice water, and freeze in a single layer before bagging.
For a continuous harvest, start a second indoor tray 3 weeks after the first. In mild climates, a spring planting and a separate fall planting together extend the season to 3–4 months total.
Celery
Gardeners have long set celery alongside cabbage-family crops, and the two do share a taste for steady moisture and rich soil. No pest or growth benefit has been demonstrated, so treat it as a convenient bedfellow rather than protection.
Onion
The strong smell of onion foliage can help hide young broccoli from cabbage root fly and aphids, which locate their target by scent. Results vary, so keep row cover on transplants as the primary defense.
Garlic
Garlic's pungent leaves can muddle the scent trail aphids follow to new brassica growth. Fall-planted garlic also finishes early, freeing the space before broccoli reaches full spread.
Nasturtium
Aphids and cabbage white butterflies often settle on nasturtium first, drawing pressure off the heads. It only helps if you check the decoys weekly and pull or spray infested growth before the colony spreads back.
Dill
Dill's flat flower heads draw in hoverflies, lacewings, and the tiny parasitic wasps that attack cabbageworm and aphid colonies. Let a few plants flower at the bed edge rather than cutting every stem for the kitchen.
Strawberry
Old companion charts keep strawberries and the cabbage family apart, though no mechanism has ever been shown. The practical caution is simpler: broccoli is pulled and the bed reworked each season, which disturbs a strawberry planting meant to stay put for years.
Tomato
Gardeners have long separated these two, and there is no demonstrated interaction behind it. What is real is timing and appetite: both are hungry crops, and a caged tomato throws shade over broccoli just as heads should be sizing up.
Give the cabbage family 4 years away from this spot before any of its relatives return.
The tomato family, the pea and bean family or the carrot family thrive in this ground next season.
Broccoli leaves the bed hungry and gives nothing back, so work in compost before the next crop. Keep all cabbage-family plants out of this ground for 4 years to starve out clubroot and black rot. Follow with the tomato family, peas or beans, or carrots and their relatives.