The Celosia Year: From a Late Sowing to Dried Stems for Winter

The shape of the season

Celosia takes roughly ten to twelve weeks from sowing to a full sized flower head, and then holds and extends that display until the first frost kills the plant outright. There is no dormancy, no overwintering and no cutting back for next year. The whole year is one uninterrupted run, and it is decided almost entirely in the first six weeks.

The counterintuitive part is that starting earlier makes things worse. Sowing four to six weeks before your last frost, rather than the ten or twelve weeks common for other bedding, is what lets you plant out a young unchecked plant into warm ground. A sowing made too early produces a plant that is ready long before the soil is, and holding it back in its pot is exactly what stunts it.

Late winter to spring: resist starting early

The most useful thing you can do with celosia in early spring is not sow it. Work out when your soil will genuinely be at 60F (16C), which is usually a fortnight or more after your last frost date, then count back four to six weeks and sow then. Everything about this plant rewards a late start into warmth and punishes an early start into a cold windowsill.

Use the waiting time on the bed. Fork it over, work in an inch (2.5 cm) of compost, and check drainage after a rain, because celosia is one of the few annuals that dies outright from wet feet. Mark out your spacing while the bed is empty and easy to measure, since spacing decided with plants in your hand is always too close.

When you do sow, sow thinly onto the surface and put the tray somewhere really warm. Transplant into individual cells at the first true leaves and then keep the plants moving. A celosia should be in the ground four to six weeks after it germinated, not ten.

If you already have plants in flower in small pots, either from a nursery or from your own early sowing, pinch the heads out at planting and feed them. They will branch and give you something, but do not expect the height a later sown plant reaches.

Early summer: the six weeks that set the height

From planting out until the plants reach around 18 in (45 cm), your only job is to prevent any check. Keep the root zone evenly moist with deep soaks rather than daily splashes, mulch once the soil is warm, feed lightly every two to three weeks, and get netting or stakes in at 12 in (30 cm) while the roots are still shallow enough not to be damaged.

Watch for early buds. A bud appearing on a plant under about 10 in (25 cm) tall means something has gone wrong, most often a dry spell or a cool week. Pinch it out at a leaf pair, water and feed, and the plant will branch. Do not pinch a crested type that is already at full height if you want a single large comb from it.

Slugs and cold nights are the two early summer risks. Torch check for the first week after planting, and if a genuinely cold night is forecast, cover the young plants with row cover or a cloche. One night at 45F (7C) is enough to trigger the stunting this plant is famous for.

Midsummer to frost: cut, dry and clear

From the first heads onward the routine is steady. Go down the row every four or five days, cut anything ready on a long stem back to a leaf joint, remove faded heads the same way, take any spotted or mildewed leaf out of the bed, and water the ground rather than the plants. Celosia carries on through the hottest weeks of the year while other bedding is failing, so this is when it earns its place.

Cutting for drying happens over several weeks rather than on one day. Take each head when it is fully colored and firm to a gentle squeeze but before it has finished setting seed, strip the leaves, tie loose bunches of five or six and hang them upside down somewhere dark, dry and airy for two to three weeks. Cutting spread across the season gives better stems than a single rush before the frost.

Leave two plants uncut late in the year if you want seed, and bag or cut the heads before they shatter, because a mature celosia head sheds a remarkable quantity of fine black seed. Then the frost ends everything in one night. Pull the plants, take the material out of the garden rather than leaving it on the soil, and note down what you want to change.

1. Cut and deadhead every four or five days Always back to a leaf joint 12 to 18 in (30 to 45 cm) down, never just under the head. Side shoots break below the cut and carry the next flush.
2. Take drying stems as they reach firmness Squeeze the base of the head. Solid and fully colored, with seed not yet shed, is the moment. Spread this over weeks rather than cutting everything at once.
3. Hang bunches in the dark for 2 to 3 weeks Strip all leaves, tie five or six stems loosely, hang upside down with air moving. They are dry when a stem snaps instead of bending.
4. Stop feeding once heads have colored Late nitrogen keeps stems soft when you want them hardening. Soft stems are why tall plants end up flat on the soil after an autumn storm.
5. Leave two plants for seed, and bag the heads Mature heads shed a great deal of fine black seed. Tie a paper bag over them or cut them into a bag before they start dropping.
6. Clear the bed after the first frost Pull the dead plants and remove the foliage from the garden. Leaf spot and mildew both overwinter on woody celosia debris left lying on the soil.

Write down four dates each year: sowing, planting out, the first flower head, and the first frost. Two seasons of those numbers tell you precisely how late you can sow and still get full height, which is the whole difficulty with this plant.