Look closely at the head. A ricey curd has a grainy, fuzzy surface where the tiny flower buds have started to swell and separate. A loose head has split into smaller clusters, sometimes with small leaves growing up through the curd. A purple, pink, or reddish blush on a white variety is pigment, usually strongest on the side facing the sun; yellow or brown patches on top are sun damage. A tinged head is safe to eat. Don't confuse this with varieties bred to be purple or orange, such as Graffiti or Cheddar, which are meant to look that way.
Heat during head formation is the most common cause. Cauliflower is the most temperature-sensitive of the cabbage family; it grows best around 60 to 65°F, and Clemson Extension describes it as extremely sensitive to temperatures that are too hot or too cold. Illinois Extension attributes leaves in the head and heads splitting into loose, smaller curds to plants maturing in hot weather. Hot, sunny spells also tend to bring the purple tinge and a stronger flavor. Spring plantings are most at risk, because heads form as the weather warms; fall plantings mature into cooling weather.
Harvest timing is the next most likely cause. The curd develops quickly: heads are usually ready 7 to 12 days after blanching begins, and a head left past that point turns coarse and ricey. Sun on an unblanched head causes yellowing and discoloration. Any interruption in growth, including dry soil, cold, heat, or root damage, can also hurt the head, and Utah State University Extension notes that plants short of water in hot weather tend to make more open heads. Tiny heads on stunted plants, called buttoning, are a different problem, usually from cold or stress early on.
Harvest affected heads now while they are still firm. A slightly ricey or tinged head is still good to eat; cut it with a few outer leaves attached to protect it, and use it soon, cooked or raw. Trim away any brown, sunburned spots. If other heads in the planting are still tight, tie or fold the outer leaves over them once the white curd shows 2 to 3 inches across, and check every day or two. In warm weather a head can go from tight to loose in a few days, so err toward cutting early.
Next time, time the crop so heads form in cool weather. For spring, set out sturdy transplants around your last spring frost, avoid stressing them with dry soil, and choose fast-maturing varieties. In many areas a fall crop is more dependable: count back from your first fall frost using the on the seed packet, plus about 2 weeks for slower growth in shortening days. Keep the soil evenly moist through head formation. Grow self-blanching varieties or tie the leaves over white types; orange and purple types don't need blanching.
- Imported CabbagewormRagged holes in brassica leaves with pale green caterpillars and green frass nearby.
- Fruit CrackingTomatoes crack at the stem end or shoulder, cabbage heads split, and carrots split lengthwise — usually after heavy rain follows dry weather.
- Blossom End RotDark, sunken, leathery patch on the blossom end of tomato or pepper fruit. The developing fruit is short of calcium, usually because of uneven watering rather than a lack of calcium in the soil.
- Gray Mold (Botrytis)Gray-brown fuzzy mold on fruit, flowers, or stems — soft, collapsing tissue beneath the coating in cool, wet conditions.
- Brown Marmorated Stink BugSunken, corky dimples on fruit and pods caused by a mottled brown shield bug feeding through the skin.
- Why did my broccoli skip making a head and go straight to flowers?Broccoli bolts when it experiences heat or stress during head formation — once it starts flowering, the head is unsalvageable, but timing adjustments can prevent it next season.
- My transplants look wilted and sad after planting — is this normal?Some wilting and leaf drop in the first few days after transplanting is normal; if a plant is still wilting after a week and well-watered, the roots may have been damaged.
- When should I start seeds indoors?Count backward from your last frost date using the seed packet's weeks-to-transplant number — most tomatoes and peppers go in 6–8 weeks before last frost.
- How can I extend my growing season in fall?Row cover fabric, cold frames, and switching to cold-hardy crops are the three most reliable tools for extending production 4–6 weeks past your first fall frost.