Cauliflower is a finicky plant, susceptible to all sorts of challenges. Sometimes, even with the best preparation, stuff just happens. Below are some of the most common problems, and what to do about them.
Buds, not curds
If your cauliflower creates small buds, not a single large curd, chances are it suffered a temperature or water shock. Cauliflower will start creating small buds if the temperature drops too low (below the 60’s). Later on, if the temperature rises too high (above 75), it may flower before the curd has a chance to grow fully. Inconsistent watering can also cause it to have challenges. Plant covers can help regulate the temperature, and the urbaculture planter system will help you keep watering consistent.
Discolored Leaves
A variety of issues can cause cauliflower leaves to turn yellow or blotchy. Below are some specific situations, what causes them, and what to do about them.
Yellow spots on leaf tops, with powdery grey on undersides
This is downy mildew, which sucks the nutrients from the leaves where it grows. It grows in damp areas, and suggests that there isn’t enough air circulating to keep the undersides of the leaves dry. Make sure there is plenty of space between the leaves and your soil, and remove any plant debris that might be blocking air flow.
Yellowing from bottom to top
If your cauliflower plant starts turning yellow near the soil, then rising up the leaves, this typically means it doesn’t have enough nitrogen. Add some compost tea or alfalfa to rebalance the nitrogen levels.
Yellowing leaves with brown veins
Dull yellow leaves are known as “Cabbage yellows” or “Fusarium wilt” and are the result of infestation by Fusarium fungi. This can occur from bottom to top as well, as the fungus grows from the roots, but unlike nitrogen deficiency, Fusarium is accompanied by a browning of the veins. The leaves eventually curl as the fungus clogs the plant.
Fusarium appears in warm temperatures. When it appears, there isn’t a lot that can be done. Fusarium is very hardy, and while its growth is stopped by cold temperatures, there isn’t any good cure. The plants must be removed, and the soil replaced, as the fungus can survive dormant up to seven years.
It can be prevented by keeping the garden free of leafhoppers, which can spread this fungus, and by making sure that your soil is well-drained.
Leaves yellowing from the edges, with black veins
This is black rot, a seed-borne bacterial infection. While the plant itself is irretrievable, this is not as damaging to the planter as Fusarium wilt. While the bacteria can travel between densely populated plants, if they are spaced further apart the other plants may avoid contracting this. The best preventative step is to use the planter only every other year for cruciferous vegetables (cauliflower, broccoli, cabbages) and plant other vegetables that don’t contract this disease during those alternate years.
Leaves yellowing with shiny or black spots and curling tightly
This is a sign of aphid infestation. Cover the leaves with soapy water to remove the spots and deter the aphids. You can also place aluminum foil as a mulch around the plants to confuse them. (Which sounds adorable — weaving aphids bumbling into the ground….) Fabric cover helps prevent them from reaching the plants.
Yellowing leaves with sticky undersides
This is a sign that whiteflies have come to visit. The sticky substance is a secretion from their ingesting the leaf juices.
Whitefly traps can be useful, although they may also capture beneficial insects. They can also be repelled with a spray made of the following mixture:
- 2 parts rubbing alcohol
- 5 parts water
- 1 tablespoon liquid soap
Leaves with yellow and/or white blotches and curling/wilting
This can be a sign of harlequin bugs and stinkbugs. Harlequin bugs are black with bright red, yellow or orange markings, while stinkbugs look like green shields, or pistachios with legs. Both bug types suck the life out of the leaves, causing this issue. They and their eggs need to be removed by hand. Keeping the planter free of detritus and weeds removes their living spaces. Fabric cover prevents them from getting close.
Disfigured Plants
When your cauliflower just isn’t looking right, here’s what’s up.
Holes in leaves, leaves eaten around the veins
Yes, long bugs have joined the party. Whether it is caterpillars, cabbage worms, or other larvae, the solution is to find them and pick them off the plants. You can also spray the plants weekly with Bacillus thuringiensis if there are too many to deal with by hand. Again, the simplest solution is garden fabric preventing the adult insects from getting close enough to lay eggs.
Holes in leaves, slime everywhere
Yup. Slugs and snails. A couple of simple ways to keep them away from your food:
- Cover soil with crushed egg shells or diatomaceous earth. These materials irritate slug and snail feet, like humans walking on glass.
- Use an iron phosphate anti-snail product. This is safe to use around plants, because iron phosphate naturally occurs in soil and works as a fertilizer as it breaks down.
You can also use beer and citrus rind baits, but they require cleaning out snail and slug remains.
Clusters of tiny holes (“shotholes”)
These are the result of flea beetles, which tend to show up in the spring to eat your plants. They can be repelled with the same mixture used to repel whiteflies.
Sudden wilting
If the plant has misshapen, gnarled roots, this is a result of clubroot, a particularly nasty fungal infection that spreads easily through the soil. The plants must be dug up and disposed of, not composted. Increasing the soil pH to above 7.2 can help to clear the fungus, or the soil should be sterilized or replaced.
Wilting with brown or deteriorated stem bases, holes in stems
This is typically a sign of worm or larval infestations. Infected plants and the surrounding soil should be removed. While individual worms and bugs can be removed by hand, the best solution is prevention. Keeping the soil well-drained helps and, of course, plant covers.