Disorder
Failure to flower
Also called Shy flowering, Not flowering, No blooms
A wisteria in leaf and nothing else, a hydrangea that flowered once, a camellia that never sets buds. The five reasons a plant refuses to flower, in the order worth checking.
At a glance
- Type
- Disorder
- Cause
- Growing conditions
- Severity
- Destroys the crop or display
- Affects
- Garden plants, Houseplants
- Active
- All year
What you are seeing
- Vigorous healthy growth with plenty of leaves and no flower buds at all
- A plant that flowered when bought and has not since
- Flowering on only the lowest part of a shrub, or only on one side
- A wisteria putting out metres of whippy growth every summer and no racemes
- A hydrangea that produces leaves in spring where the flower buds should be
- A bulb that comes up blind, with leaves and no stalk
- Buds forming and then never developing
Before you treat anything
Nothing here is harmful. Wisteria seeds and pods are toxic if eaten, which becomes relevant only once the plant does flower.
Five questions, in this order
A healthy plant that will not flower has a reason, and running through these in order finds it in almost every case.
Is it old enough? Wisteria raised from seed can take twenty years, and a great many disappointing wisterias are seedlings sold cheaply without a graft. Look at the base for a graft union. Magnolias, tree peonies, many trees and most fruit take several years to reach flowering size, and nothing is wrong.
Is it being fed nitrogen? A shrub growing magnificently and flowering not at all is usually a shrub with too much nitrogen. Lawn feed drifting into a border, a general growth fertiliser applied every spring, or a heavy mulch of fresh manure will all do it. Nitrogen buys leaves and potassium buys flowers.
Is it in enough light? Flowering is expensive and a shaded plant cannot afford it. A shrub flowering only on its sunny side has already told you the answer.
Is it being pruned at the wrong time? More shrubs are pruned out of flower than are lost to any pest on this site. Anything flowering before midsummer is usually flowering on last year’s wood, so a tidy-up in February removes the entire display. Forsythia, lilac, philadelphus, weigela, deutzia and spring clematis all want cutting back straight after they flower and at no other time.
Was it stressed at the wrong moment? A camellia short of water in August has no buds in March. A daffodil whose leaves were cut down in May comes up blind the following spring. Both of those decisions are taken months before the disappointment.
Wisteria deserves its own paragraph
Most wisterias that do not flower are pruned wrongly rather than fed wrongly, and the fix is specific.
Cut the long whippy growths back to about five leaves in July or August. Then in January or February, cut those same shortened shoots back again to two or three buds. That is it, twice a year, and it converts the plant’s energy from extension growth into flowering spurs.
A grafted plant pruned this way, in full sun, without nitrogen, flowers within two or three seasons. A seedling will still take as long as it takes.
Bulbs coming up blind
A daffodil forms next year’s flower inside the bulb during the six weeks after this year’s flower fades, and it pays for that with the leaves.
Cutting the foliage down, tying it into knots or mowing over it during those six weeks removes the plant’s income at the exact moment it is investing. The result is leaves and no flower the following spring, and it is entirely self-inflicted.
Leave the foliage for six weeks after flowering, feed with a high-potassium feed, and lift and divide congested clumps in summer.
What to do about it
Check the age and look for a graft union.
Stop all nitrogen and switch to sulphate of potash or a tomato feed in spring.
Get more light onto the plant, by moving it or by cutting back what shades it.
Find out whether it flowers on old or new wood, and prune accordingly. When in doubt, prune immediately after flowering.
Prune wisteria in July or August and again in January or February.
Leave bulb foliage alone for six weeks after flowering, and feed it.
Leave clivias, agapanthus and orchids in tight pots.
Deadhead the things that stop once they set seed.
What it gets mistaken for
Bud drop means the buds formed and were shed, and the plant is telling you something different.
Frost kills formed buds in a night, and the browned remains stay attached.
Nutrient shortage produces a pale, small, unhappy plant. This page is about plants that look wonderful.
Reversion on a variegated or grafted plant produces vigorous plain growth from below the graft that swamps the flowering part, and cutting that growth out at the base is the answer.
Biennial bearing in apples and pears produces a heavy crop one year and none the next, which is a rhythm rather than a fault, and thinning the fruit in the heavy year evens it out.
What to do, in order
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Start here
Prevention, and the changes that stop the problem returning. Most of these pages should end at this tier.
- Check the age first
- Wisteria from seed takes up to twenty years to flower and is a common and expensive disappointment, which is why grafted plants are worth the money and worth checking for a graft union at the base. Magnolias, tree peonies and many trees take years to reach flowering size. Where a plant has not reached that size, nothing needs doing except waiting.
- Cut the nitrogen out
- This is the commonest fixable cause. A shrub in a border fed by lawn fertiliser drifting off the grass, or one given a general growth feed every spring, puts everything into leaves. Stop feeding nitrogen, and use a high-potassium feed such as a tomato feed or sulphate of potash in spring instead.
- Give it more light
- Flowering is expensive and a plant in shade cannot afford it. Wisteria, roses, most fruit and nearly all bulbs want full sun. A shrub that flowers only on its sunny side is telling you exactly this, and the answer is either to move it or to cut back whatever is shading it.
- Find out when it flowers on
- More shrubs are pruned out of flower than any other single cause. Anything that flowers before midsummer usually does so on wood made the previous year, so cutting it back in winter removes the flowers. Forsythia, lilac, philadelphus, weigela, deutzia and spring clematis all want pruning straight after flowering, and never in spring.
- Feed and water a bulb after it has flowered
- Daffodils and tulips build next year's flower inside the bulb during the six weeks after this year's flower fades, using the leaves. Cutting the foliage down, tying it in knots or mowing over it produces blind bulbs the following spring. Leave the leaves for six weeks and feed.
- Leave a pot-bound plant tight
- Clivias, agapanthus, hoyas, peace lilies and many orchids flower better crowded and produce leaves when repotted generously. Potting one on to encourage it is a common way to lose a season of flowers.
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Then reach for a barrier
Netting, hand removal and water. Nothing here harms anything except the target.
- Prune a wisteria twice a year
- Cut the whippy summer growth back to about five leaves in July or August, then cut those same shoots back again to two or three buds in January or February. It is the single most reliable intervention in this entire page and it turns a non-flowering wisteria round within two seasons.
- Restrict the roots or bark ring a stubborn tree
- An over-vigorous fruit tree that will not fruit can be brought into flower by root pruning in winter, cutting a semicircular trench a metre or so from the trunk and severing the roots on one side. It is a traditional technique, it works, and it is worth trying before giving up on a tree.
- Deadhead where it prolongs the season
- Sweet peas, roses and many annuals stop flowering once they set seed, because seed is what they were flowering for. Regular deadheading keeps them going for months.
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.