Vegetable · Brassicaceae
Cauliflower
Brassica oleracea Botrytis Group
Keep it cool, fed, and never thirsty, and the curd packs into one tight, heavy, snow-white dome.
Full sun
Every 3–7 days
45–75°F · 7–24°C
55–100 days
Overview
Cauliflower is a cool-season cousin in the cabbage family, raised for the dense pale head, the curd, that swells at the heart of a low rosette of wide blue-green leaves. The same wild ancestor gave us cabbage, broccoli, and kale, yet breeders steered this branch toward a single packed cluster of unopened flower buds. Cut it on time and the dome is firm and smooth; wait too long and the surface loosens into rough grain almost overnight.
It ranks among the fussier brassicas to bring to a clean head. From the first true leaf to the cut, the plant craves even, cool air, and it answers any slip with a smaller, coarser curd. One cold snap, one hot stretch, or a run of dry days can stall the rosette and shrink the head down to a hard little knot.
Color runs through the lineup now. Beside the standard white, the heads come in orange, deep purple, and the lime-green spiraling Romanesco, and each colored type holds its pigment only out in full sun, never under tied leaves. Match the type to your season and your patience, and the head shows up to suit it.
Care
The short version: plant it in full sun and rich loam held evenly damp near pH 6.0 to 7.0, feed it heavily, and most of all keep the rosette growing cool and unchecked from the first leaf to the cut.
Light
Cauliflower craves full sun, six hours a day or more, though it tolerates a little afternoon shade where spring heats up early. The colored heads in particular lean on that sun to deepen their orange, purple, or green skin.
Water
Even moisture decides everything here. Give the bed about 1 inch (2.5 cm) of water a week and never let the roots run dry, since one bout of drought stress can wreck the curd or set off buttoning. Sandy soil drains faster than clay, so reach for the hose more often there.
Soil
Set plants into rich, fertile, well-drained loam turned through with compost or aged manure, the kind that grips moisture without turning to muck. A pH of 6.0 to 7.0 keeps nutrients within reach and helps head off the hollow stem that acidic ground brings on.
Temperature
This is a cool-season crop, happiest between 45°F and 75°F (7°C to 24°C). Days that hang above 86°F (30°C) or nights that stay warm will abort or warp the curd, so place the crop to slip past the real heat.
Humidity
Plain outdoor air around 40% to 70% suits it fine, with no figure to chase. Moving air through the planting counts for more, since damp leaves packed tight together draw disease.
Feeding
Cauliflower is a heavy feeder. Turn a balanced fertilizer such as 5-10-10 into the bed before planting, side-dress with nitrogen about 3 to 4 weeks after transplanting, and keep boron topped up so the curd stays white instead of browning.
Pruning
Nothing is cut for shape, but white heads call for blanching: once the curd hits 2 to 3 inches, gather the outer leaves up over it to hold the pale color, unless the variety wraps itself. Leave orange, purple, and Romanesco heads bare to the sun, and strip off any battered outer leaves.
Repotting
Cauliflower is no houseplant, so there is no repotting round. Sow seed in cells or flats and shift each plant once into the garden about 4 to 6 weeks after sowing, before the seedling hardens off and stiffens into woody growth.
Size & spacing
Plants stand 12 to 24 inches (30 to 60 cm) tall and spread about as far across. Set them 18 to 24 inches (45 to 60 cm) apart so each rosette has the elbow room to swell a full head and air can drift down the row.
When to plant
Cauliflower lives by cool air and balks at both frost and heat. Sow seed indoors and move sturdy transplants out a few weeks ahead of the last spring frost, or in mid- to late July for a fall round, then cut the heads while the cool weather still holds.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Spring crop: start seed indoors about 4-6 weeks before the last frost (around April in cold climates). Fall crop: start seed in July, indoors or direct-seeded.
- Plant: Transplant 2-3 weeks before the average last spring frost, or mid- to late July for a fall crop; space plants 18-24 inches apart.
- Harvest: Harvest the curd when full-sized, firm, and still tight/white, before the florets begin to separate; cut with a few wrapper leaves attached.
Hardiness
USDA hardiness zones: 3–10
Temperature: down to -40°C
Troubleshooting
Nearly every cauliflower problem comes back to a single thread, a break in steady growth, and it tends to surface either in the curd itself or across the broad leaves. Read these early marks well and you can step in before one small stumble takes the entire head. Match what sits in front of you below, then act while action still counts.
Yellow wedges at the leaf edge or roots swollen into clubs
Two soilborne troubles share this look. Black rot scorches yellow V-shaped wedges inward from the leaf margins and darkens the veins to near black, while clubroot bloats the roots into knobby, distorted clubs that choke off water until the whole plant flags and wilts. Once either takes hold there is no saving the plant. Dig out and destroy anything infected, set out only clean transplants, hold a rotation of at least four years away from every cabbage-family crop, and lean on resistant varieties.
Fix:
- Remove and destroy infected plants
- Use clean, disease-free transplants
Marble-sized heads where a full curd should be
What you are looking at is buttoning: a chilled, baked, parched, or pot-bound young plant abandons the broad curd and pinches out a hard knot the size of a marble instead. The leafy rosette stays small while that tiny dome perches at its center. Plant out young, springy transplants on schedule, keep them growing without a hitch, and skip any start that has gone root-bound or stiff and over-hardened.
Fix:
- Keep plants growing vigorously with steady water and nutrients
- Replace stressed plants; avoid root-bound or over-hardened transplants
Curd gone grainy as the florets break open
A ricey curd wears a fuzzy, pebbled surface where the once-smooth dome has roughened into separate grains. Warm air does this, prodding each tiny flower bud to stretch and pull free of its neighbors before harvest. Plan the crop so the head fills out in the cool, cut it the instant it sizes up, and pull back on the nitrogen.
Fix:
- Harvest promptly before florets separate
- Time the crop so the curd matures during cool weather
Tattered leaves hiding plump green worms
Run a finger along the underside of a chewed leaf and you will turn up cabbageworms, cabbage loopers, and diamondback moth larvae, soft velvety green caterpillars trailing dark crumbs of frass across the ragged blades. Flea beetles riddle the same foliage with pinprick shot-holes, hitting tender seedlings hardest. Pluck the worms by hand, switch to Bt once they outpace you, and tuck young plants under a floating row cover.
Fix:
- Handpick caterpillars
- Apply Bt (Bacillus thuringiensis)
- Cover young plants with floating row cover
Rusty stains on the curd or a brown, hollowed stalk
Boron deficiency sits behind most of this, smudging the white florets rust-brown and leaving the inner stalk discolored or scooped out into a hollow core. Acidic soil and erratic watering deepen the damage. Test the soil first before reaching for any boron, hold the pH where it belongs, and water on a dependable rhythm.
Fix:
- Correct boron based on a soil test
- Maintain proper pH and even moisture
Toxicity
Cauliflower is a plain garden vegetable with nothing poisonous in it, so the whole plant is yours to grow and cut around children and pets. Being a brassica, it does carry goitrogens and some gas-raising fiber, so a heavy raw helping might unsettle a pet's stomach, but the plant is in no way toxic.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Nothing in the leaf or curd is toxic to cats, so a curious bite leaves them perfectly fine.
Dogs None
Dogs handle cauliflower without trouble. A big mouthful of the raw plant might stir up a touch of gas, yet nothing harmful comes of it.
Horses None
Horses face no poison from this plant, though like any brassica it can sit heavy in the gut, so offer only modest bites.
Rabbits None
Leaves and curd suit rabbits in small servings. A heap all at once can bring on gas, so keep the portion light.
Livestock None
Cattle, goats, and sheep may graze the plant with no fear of poisoning, since it holds nothing toxic for them.
Birds None
Hens and other backyard birds can peck happily at the leaves and curd with not a worry.
People Safe
A familiar kitchen vegetable, eaten raw or cooked with zero risk. Every part of the plant is safe to touch and to harvest.
As a brassica it contains goitrogens and can cause gas/bloating; large quantities may cause mild, temporary digestive upset in pets, but the plant is not poisonous.
Varieties
Cauliflower reaches well past plain white. A handful of names cover most home plots, running from early dependable hybrids to the bright colored heads.
Snow Crown
Reliable white hybrid that shrugs off a touch of warmth and sets a head in roughly 50 to 60 days, which makes it a top choice for the spring bed.
Amazing
White curd that folds its own leaves over the head, asking for little or no hand-blanching while taking varied conditions in stride.
Cheddar
Glowing orange head loaded with beta-carotene, deepening that color under open sun rather than beneath tied leaves.
Graffiti
Deep purple curd stained by natural anthocyanins, a head that must stay open to the light and never be blanched.
Romanesco
Lime-green head that coils into a pointed fractal spiral, drawing its color from sunlight rather than blanching.
Companions
Cauliflower's worst neighbors are its own relatives, the other cabbage-family crops that pass the same pests and soil diseases back and forth.
Keep apart
Other brassicas (cabbage, broccoli, Brussels sprouts, kale, turnip): Share the same pests and soilborne diseases (cabbageworms, clubroot, black rot); extension guidance is to rotate and avoid planting them together for several years.
How to propagate
Cauliflower starts from seed, and the whole game is the transplant: grow stout young plants and set them out before they ever break their stride.
SeedModerate
Start indoors about 4-6 weeks before transplanting; sow in early spring (around April) for a spring crop and in July for a fall crop. · Transplant-ready in about 4-6 weeks; curd harvest roughly 55-100 days after transplanting.
Cauliflower almost always comes up as a transplant rather than a direct sowing, which keeps the young plants springy and clear of the growth checks that set off buttoning. Sow indoors about 4 to 6 weeks before setting out, and figure roughly 55 to 100 days from transplant to a head worth cutting.
Myths
A cauliflower can only turn white if you tie it shut.
Many of today's cultivars blanch themselves, curling their own leaves across the head, so hand-tying falls only to certain white types. Orange, purple, and Romanesco kinds need full sun to color up and must never be blanched.
Cauliflower and broccoli are really one and the same.
They spring from a single species, Brassica oleracea, yet they do not stand in for each other. Cauliflower belongs to the Botrytis Group and broccoli to the Italica Group, two separate cultivar lines.
Cauliflower is simple, just one more cold-tough crop.
Few brassicas are harder to bring to a clean head. It demands steady, cool conditions and reacts badly to both heat and any check in its growth, which is what brings on buttoning and ricey curds.