Question: I want to make room in my garden for other vegetables and grow more plants in containers. Can cauliflower be grown in pots? Should I grow it differently than when planting in the ground? -Heather F.
Answer: Cauliflower is a relatively large vegetable, but its root system is actually very shallow compared to other vegetables of a similar size. As long as you have containers that are wide enough to accommodate cauliflower plants, you should have no problem growing them in pots at home.
Select a container that is 12 to 18 inches wide and at least eight to twelve inches deep for a single cauliflower plant. Larger containers, such as half whiskey barrels, can accommodate up to three cauliflower plants at a time. Any type of container that meets the size requirements will suffice, as long as it has at least one large drainage hole at the bottom. Cauliflower plants will not abide soggy soil, and will quickly rot and die in standing water.
Provide your plants with a loose, well draining potting soil with good moisture retention. Any store-bought mix with peat, compost, fine bark, and either vermiculite or perlite will perform beautifully. Never use garden soil for your cauliflower containers, as it can easily become compacted, and will stop air from being able to reach the roots, which will suffocate the plant.
Directly plant cauliflower seeds outdoors when temperatures reach 50 degrees F, or start your seeds indoors about a month before the last average frost in your region. Alternatively, for an easier start, you could opt to purchase seedlings which are ready for transplant from your local nursery or garden center. Plant seedlings about one month prior to the last average frost date in your climate if you want to harvest your cauliflower in the spring. For fall harvests, plant seedlings around six weeks before the last average frost in your area.
Choose a location that receives at least six hours of direct sunlight per day and provide water whenever the soil feels dry to the touch. If the soil is still moist, wait to water until it has fully dried on the surface level, as cauliflower will not survive in soggy soils. Don’t wait until the soil has gone completely dry throughout the pot to water, but allow the surface to dry out between waterings. When watering, keep it going until you see it begin to drain from the bottom of the container.
For fertilization, mix a dry, time-release fertilizer into the soil prior to planting, or feed your cauliflower once per month using a balanced, water soluble fertilizer. Your cauliflower plants may need a bit of assistance to keep their heads tender and white when you are ready to harvest. Some varieties of cauliflower are self-blanching, producing leaves that naturally curl over the developing head to protect it from direct sunlight. These varieties will require no assistance, but others may need a little help. Keep an eye on your plants when the heads get to be about two inches across. If the leaves aren’t doing an adequate job of curling over to protect the heads, help them do so by pulling the large outer leaves up around the head and secure them with a clothespin or a small bit of string.
When the heads become compact, white, and firm to the touch, it is time to harvest them. Ideally, the heads will be six to eight inches in diameter at harvest time, but the size may vary based on the variety, the climate in your region, and the food and water that was provided throughout the growing season. Cauliflower plants are usually ready to harvest around 50 to 100 days after planting, depending on variety, or seven to 12 days after blanching.
Cut the heads off with a large knife, being careful to leave some of the leaves around the head for protection. If the heads seem too small but have already begun to open up, go ahead and harvest immediately, as they are not going to improve once they have started to open. If the heads look coarse, it has past maturity and needs to be discarded.
Store cauliflower heads inside a plastic bag in the fridge. They will stay fresh for about a week. For long-term storage, you can either freeze or pickle your cauliflower heads. To freeze, cut into one-inch pieces and blanch them by boiling for three minutes in lightly-salted water, then cooling in an ice water bath for another three minutes. After blanching, drain them in a colander, pat them dry with a paper towel, package them in serving sizes in separate freezer bags, then seal and freeze.