Gadenin日本語Get the appThe shape of the agapanthus year
Agapanthus runs on a simple annual rhythm and most of the work falls into two short bursts. Spring is when you restart watering, begin the high potash feed and protect emerging growth. Late summer is when you cut down spent heads and begin tapering off. The rest of the year is largely a matter of leaving the plant alone, which for this species is not laziness but active management.
Two things change the calendar. The first is whether your plant is evergreen or deciduous, which decides everything about the winter half of the year. The second is whether it is in a container or in open ground, since containers need far more watering attention in summer and far more protection from rain in winter. Everything else is common to all agapanthus.
| Season | Main job | Watering | Feeding | Watch for |
|---|---|---|---|---|
| Early spring | Clear the crown, pull back winter mulch, bring pots back outside after frosts | Restart as new leaves show, keeping the mix just moist | Begin high potash liquid feed every two weeks | Slugs on soft new growth, late frost on emerging buds |
| Late spring | Divide only if the clump is genuinely old, and settle new plantings | Water in dry spells, letting the surface dry between | Continue high potash every two weeks | Leaves stretching, a sign of insufficient sun |
| Early summer | Support tall stems in exposed spots before buds open | Water containers freely, ground clumps only in drought | Continue until buds show color, then stop | Aphids on developing flower stems |
| Midsummer to late summer | Enjoy the flowering, remove each head as it goes over | Keep containers evenly moist while in flower | None | Pots drying to wilting point in heat |
| Autumn | Cut spent stems to the base unless keeping seed heads, tidy foliage | Reduce steadily as growth slows | None | Waterlogged pots after autumn rain |
| Winter | Evergreens under cover, deciduous mulched in place | None for deciduous, minimal for evergreen | None | Rot at the crown, standing water around pots |
Spring: the season that decides the summer
Everything that matters for flowering happens now. Clear away the last of the previous year's foliage so the crown is open to air and light, and rake the winter mulch off deciduous clumps once hard frosts are past. Move overwintered evergreen containers back outside gradually, giving them a week in a sheltered spot before full exposure, so the leaves do not scorch in stronger sun.
Start watering as soon as new leaves appear, but keep it moderate; the roots are still rebuilding and cold wet compost at this stage causes rot. Begin the high potash feed with the first new growth and apply it every two weeks. Resist any temptation to repot. A plant that looks cramped in spring is a plant preparing to flower, and moving it now is the single most effective way to guarantee an empty summer.
Watch for two threats. Slugs graze the soft emerging leaves, and a late frost can kill the developing flower bud inside the crown with almost no visible sign. Row cover over the crown on a clear cold night costs nothing and can save the entire season's display.
Summer: water, support, and then deadhead
Through early summer the plant is building its stems and needs steady water, particularly in containers where a root bound plant in a small pot dries quickly. Stop feeding once the buds show color; the work of the potash is done and further feeding only pushes leaf growth. Put supports in place before the stems are tall, not after one has fallen over.
As each head finishes, cut the stem right down to the base rather than leaving a stub. A spent head left in place puts a surprising amount of the plant's energy into building seed, and that energy is taken directly out of next year's flowering. Removing the stems promptly keeps the plant working on its roots instead.
The exception is deliberate. The dried seed heads are architectural and hold well into winter, and some gardeners leave a few for that reason or to collect seed. That is a legitimate choice, but understand the trade: the clump carrying seed heads will flower a little less freely next summer than one that was cut down cleanly.
Autumn and winter: the split in the calendar
From here the two groups part company. Deciduous kinds yellow and collapse; let the foliage die back fully so the plant draws its reserves down into the roots, then clear it away so it is not lying wet over the crown, and cover the crown with a dry mulch of bark, straw or leaves. Withhold water entirely. Their hardiness means they can normally stay in the ground.
Evergreen kinds keep their leaves and need protection. Move containers into a cool, bright, frost free place before the first hard frost and water only enough to stop the root ball drying to dust, perhaps once a month. An evergreen planted in open ground in a cold area is a gamble; if you cannot lift it, mulch the crown thickly and accept that a hard winter may take it.
For every container, get the pot off the ground on feet or bricks, remove any saucer, and put it where winter rain cannot fill it. Standing water is the commonest cause of death and the easiest to prevent.
- Establish which group each plant belongs to In midwinter, note which plants still have leaves. Evergreens are the tender group and need frost free quarters. Deciduous ones are far hardier and stay outside. Label them now, because once the deciduous kinds have vanished you cannot tell them apart.
- Cut spent flower stems to the base Take each stem right down as soon as its head has gone over. Leaving them means the plant spends late summer building seed at the expense of next year's flowers. Keep a few only if you specifically want the dried heads or want seed.
- Clear the crown before winter Remove collapsed and yellowed foliage from around the growing point. Wet dead leaves sitting over the crown all winter cause rot and give slugs somewhere to shelter until spring growth arrives.
- Move pots out of the rain Stand containers on feet, remove saucers and shift them under an overhang or against a wall. A dormant plant in a pot full of winter rain is the classic loss, and there is nothing above ground to warn you it is happening.
- Do the annual repotting review, and usually decide against it Once a year, ask whether the plant genuinely needs a bigger pot. Unless the container has split or the plant has stopped flowering after many years, the answer is no. Top dress with an inch (2.5 cm) of fresh gritty mix instead and leave the roots undisturbed.
A single page of notes covers the whole cycle
Keep one line per plant per year and the calendar starts running itself. Record the date growth restarts in spring, the date the first flower stem appears, the number of stems, the date the last head was cut down, and the date the plant went under cover or was mulched. Add the pot size and the year it was last divided or repotted.
After three years those lines answer the questions that matter. Is flowering advancing or slipping? Is this clump building up or declining? How many years since the roots were disturbed, and is it finally time? They also stop the two most expensive mistakes: repotting a plant that was about to flower, and leaving an evergreen outside for one winter too many.