How to Propagate Broccoli

Wait for the broccoli plants to go to seed rather than harvesting the broccoli to eat. The plant sends up a tall flower stalk that produces green seedpods. Wait for the seedpods to begin turning brown, which means they are mature.

Pull up the plant and lay it flat on a sheet so the seeds can continue to dry. They are ready when the pods are brown and brittle. The amount of time this takes varies with the moisture level in your drying space. Check the pods twice a week.

Cover the plants with another sheet and walk on them to smash open the pods. Open the sheet and discard the main plant body. Place a fine mesh sieve over a bucket and pour the rest of the seed and pod material into the sieve. The small seeds fall into the bucket and the chaff stays in the sieve.

Pour the seeds into a plastic container with a lid. Store in a cool, dry place until spring.

Prepare the planting site in early spring by covering the ground with 2 inches of compost and tilling it into the soil at a depth of 6 inches.

Insert the seeds into the soil at a depth of 1/4 inch, spaced three inches apart. Water until the soil settles. Keep the soil moist until the plants germinate, then thin to one plant every 14 inches.