Raychis

Disorder

Bud drop

Also called Bud blast, Flower bud drop

A gardenia, camellia or Christmas cactus covered in buds that drop before opening. The three things that cause it, and why moving the plant is usually what did it.

At a glance

Type
Disorder
Cause
Growing conditions
Severity
Destroys the crop or display
Affects
Houseplants, Garden plants
Active
All year

What you are seeing

  • Buds forming normally, swelling, and then yellowing at the base and dropping
  • Buds falling at a touch, or found on the floor around the pot in the morning
  • The whole crop of buds shed over a few days, leaving a healthy plant with no flowers
  • Buds dropping shortly after the plant was moved, repotted or brought home
  • Camellia buds browning at the edges and going papery before falling
  • The plant otherwise in good health with sound foliage

Before you treat anything

Nothing here is harmful to people or pets. Check the toxicity section of the guide for any plant a pet has access to, since a plant that has dropped its buds is no less toxic than one in full flower.

What you are looking at

The plant is covered in buds. They swell, they look right, and then they yellow at the base and fall off, sometimes all within a few days. In the morning there is a ring of them on the floor around the pot.

The plant itself is fine. The leaves are sound, the growth is normal, and nothing is eating it. That combination of a healthy plant and no flowers is what brings people here.

Gardenias, camellias, Christmas cactus, hibiscus and moth orchids are the ones it happens to most.

Three causes, and one of them is you

A flower bud is expensive. A plant that is unsure of its supply lines will abort the buds rather than risk the whole plant, and almost everything on this page is a way of making it unsure.

The first cause is movement. Camellias, gardenias, Christmas cactus and hibiscus all set their buds in relation to a particular light direction, and turning the pot or carrying it to another room mid-budding is enough to make them drop. A Christmas cactus bought in bud and carried home through a cold car park very often sheds the lot within a week. Mark the pot, put it back the same way round, and leave it alone.

The second is water. A plant that dries out while budding drops buds, and it does it a week or two later, which is long enough that nobody connects the two events. Camellias are the extreme case: the buds for next March are formed in July and August, so a dry August produces a flowerless spring and the gardener spends the following winter wondering what went wrong.

The third is temperature and humidity, mainly indoors. Draughts, a radiator under the plant, and the swing between a warm evening and a cold night all trigger it. Gardenias in centrally heated rooms are the classic failure, and dry air is as much to blame as anything.

Outdoors, camellia bud loss has a fourth cause that is worth stating on its own. Frozen buds are destroyed during a rapid thaw rather than by the cold itself, so a camellia facing east and catching the first sun loses its flowers while an identical plant facing west keeps them.

What to do about it

Leave the plant where it is from the moment buds appear until flowering is over, and put it back the same way round after watering.

Keep the compost evenly moist throughout budding, checking rather than following a schedule.

Water camellias through July and August, which is when next spring’s flowers are decided.

Move camellias out of the early morning sun.

Keep gardenias and Christmas cactus away from radiators and draughts, and give them a steady, cooler position.

Stand a gardenia on damp gravel and group it with other plants.

Ease off feeding once buds are set.

Rub off the smallest buds where a plant has set more than it can carry.

What it gets mistaken for

Blossom drop sheds open flowers on tomatoes, beans and fruit trees, and the result is no fruit rather than no flowers.

Frost damage browns camellia buds and flowers on the exposed side of a plant in one night, and it goes no further.

Camellia flower blight rots open flowers to brown from the centre outwards and they hang on the plant, which is a fungus rather than a disorder.

Drought that is still going on wilts the foliage as well. Bud drop from an earlier drought leaves the leaves looking perfectly well.

Failure to flower is a different question entirely, since there the buds never form at all.

What to do, in order

  1. Start here

    Prevention, and the changes that stop the problem returning. Most of these pages should end at this tier.

    Stop moving the plant
    This causes more bud drop than everything else combined. Camellias, gardenias, Christmas cactus and hibiscus set their buds in relation to a particular light direction, and turning the pot or moving it to another room while the buds are forming makes them drop. Mark the pot, put it back the same way round after watering, and leave it where it is from the moment buds appear until the flowers are over.
    Water evenly and never let it dry out
    A plant that dries out while budding sheds the buds, and it does so a week or two later, so the connection is usually missed. Check the compost regularly through the budding period rather than watering to a schedule, and never let a camellia in a pot go dry in late summer, which is when next year's buds are being formed.
    Keep the temperature steady
    Gardenias and Christmas cactus are the fussiest. A draught from an opened door, a radiator coming on under the plant, or the swing between a warm evening room and a cold night all trigger dropping. A steady, cooler position beats a warm variable one.
    Get the humidity up around a gardenia
    Dry centrally heated air is the other half of the gardenia problem. Stand the pot on a tray of damp gravel with the pot clear of the water, group plants together, and keep it away from radiators. Misting helps for minutes rather than hours.
    Water camellias in late summer
    A camellia forms next spring's buds in July and August, and a dry spell then produces bud drop the following March. The watering that saves the flowers happens eight months before anyone notices they have gone.
    Feed in balance, and not while budding
    Too much nitrogen produces leaves at the expense of flowers, and a sudden strong feed on a budding plant can shock it into dropping. Feed through the growing season and ease off once buds are set.

  2. Then reach for a barrier

    Netting, hand removal and water. Nothing here harms anything except the target.

    Move a camellia out of the morning sun
    Camellia buds and flowers are damaged by frost mainly during a fast thaw, so a plant catching the early sun loses its flowers where one in light shade or facing west keeps them. This is the commonest single cause of camellia bud loss in a British garden.
    Thin a heavy set of buds
    A camellia or a gardenia carrying more buds than it can support will shed some regardless. Rubbing off the smallest ones leaves the plant to concentrate on the rest and produces better flowers.

Plants this turns up on

Guides that name it among the problems to watch for. The list is the plants it is characteristic of rather than everything it will feed on.

Sources