Ornamentalshrub ornamentalStraightforward

Forsythia

Forsythia × intermedia

The yellow shrub in every front garden in March, and the one most often ruined by kindness. It flowers on wood made the previous summer, so the tidy-up most people give it in early spring cuts off the whole of the following year's display — which is why so many established forsythias flower only at the very top where the shears did not reach.

Position: Full sun or Partial shade
Water: low demand
Drainage: Moisture-retentive, Free-draining
Grows to: 200–300 cm × 200–300 cm
Hardiness: H6
Flowers: March and April
Difficulty: Straightforward

Described view

A forsythia stem showing this year's flower buds on last summer's wood, beside a stem cut back after flowering with new growth breaking

August

Nothing to do

No sowing, planting, harvesting or pruning window falls in August.

Forsythia’s year

Resolved for United Kingdom (general). Every window is stored against a climate event rather than a date, so a late frost pocket runs later than the band shows. What else August calls for.

Activity	F	M	A	M	O	N
Plant	February.	March.			October.	November.
In flower		March.	April.
Prune			April.	May.
Take cuttings					October.	November.

Timing that travels

The band above resolves this plant's windows into months for one region. These are the windows themselves, stored against a climate event rather than a date — which is the form that survives being carried to a colder garden, a frost pocket, or next year.

Conditions it needs

Light: Full sun, Partial shade
Frost: Very hardy
Hardiness rating: H6 (RHS)
Grows best at: 10–25 °C
Soil: Loam, Clay, Sandy, Chalky
Soil pH: 5.5–8
Drainage: Moisture-retentive, Free-draining
Water needs: low
Drought: moderate tolerance
Waterlogging: moderate tolerance
Heat: good tolerance
Wind and exposure: good tolerance

Where these figures come from

LightSourced guidancemoderate confidence: Royal Horticultural Society: Forsythia — position
Checked 2026-08-13
FrostSourced guidancehigh confidence: Royal Horticultural Society: Forsythia — hardiness
Checked 2026-08-13
Hardiness ratingSourced guidancemoderate confidence: Royal Horticultural Society: RHS hardiness ratings
Checked 2026-08-13
Grows best atSourced guidancemoderate confidence: Royal Horticultural Society: Forsythia — temperature
Checked 2026-08-13
SoilSourced guidancemoderate confidence: Royal Horticultural Society: Forsythia — soil
Checked 2026-08-13
Soil pHSourced guidancemoderate confidence: Plant Finder — Missouri Botanical Garden: Forsythia × intermedia — culture
Checked 2026-08-13
DrainageSourced guidancemoderate confidence: Royal Horticultural Society: Forsythia — soil
Checked 2026-08-13
Water needsHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
DroughtHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
WaterloggingHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
HeatHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
Wind and exposureHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13

On your soil

Computed by comparing this plant's recorded requirements against each soil's recorded characteristics. A recorded horticultural fact overrides the comparison where GrowingHQ holds one.

Soil	Verdict	Why
Heavy clay	Works, with one condition	Forsythia will crop on heavy clay, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. A plant that stays in the ground through winter with its roots in cold, saturated soil rots — which is what kills most of what fails on heavy ground, rather than the cold.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.
Sandy	Prefers this soil	Sandy suits Forsythia as it stands: The pH suits it: it wants 5.5 to 8, and this soil is in that range. The free drainage is exactly what it wants. Sandy soil is among the soils it is recorded as suiting.
Chalky and alkaline	Grows well here	Forsythia grows perfectly well on chalky and alkaline without special measures, though it is not the soil it would choose.
Loam	Prefers this soil	Loam suits Forsythia as it stands: The pH suits it: it wants 5.5 to 8, and this soil is in that range. The free drainage is exactly what it wants. Loam is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering.
Silty	Prefers this soil	Silty suits Forsythia as it stands: The pH suits it: it wants 5.5 to 8, and this soil is in that range. The free drainage is exactly what it wants. The soil holds moisture, which saves a great deal of watering.
Peaty and acid	Works, with one condition	Forsythia will crop on peaty and acid, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. A plant that stays in the ground through winter with its roots in cold, saturated soil rots — which is what kills most of what fails on heavy ground, rather than the cold.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.
Shallow over rock	Prefers this soil	Shallow over rock suits Forsythia as it stands: The free drainage is exactly what it wants. Loam is among the soils it is recorded as suiting.
Made ground and urban soil	Works, with one condition	Forsythia will crop on made ground and urban soil, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. A plant that stays in the ground through winter with its roots in cold, saturated soil rots — which is what kills most of what fails on heavy ground, rather than the cold.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.

Not sure which you have? Four hand tests will settle it.

Space and spacing

Mature height: 200–300 cm
Mature spread: 200–300 cm
Rooting depth: 60 cm
Spacing: 150–200 cm apart

Where these figures come from

Mature heightHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
Mature spreadHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
Rooting depthHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
SpacingSourced guidancemoderate confidence: Royal Horticultural Society: Forsythia — spacing
Checked 2026-08-13

Measured centre to centre. Plants set closer than this compete for light and water long before they look crowded, and the crowding cannot be undone once they are in.

Habit and ultimate size

What the plant becomes, rather than what it is when you buy it. The gap between the two is where most planting mistakes live.

Foliage: Deciduous
In a container: Not a realistic container plant

Where these figures come from

FoliageSourced guidancehigh confidence: Royal Horticultural Society: Forsythia × intermedia — foliage
Checked 2026-08-13
In a containerHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13

Growth rate: Fast — over about 60 cm a year
Ultimate height: 200–300 cm
Ultimate spread: 200–300 cm
Time to reach it: 10–15 yearsSourced guidance

Where these figures come from

Growth rateSourced guidancemoderate confidence: Royal Horticultural Society: Forsythia × intermedia — growth rate
Checked 2026-08-13
Ultimate heightSourced guidancemoderate confidence: Royal Horticultural Society: Forsythia × intermedia — ultimate height
Checked 2026-08-13
Ultimate spreadSourced guidancemoderate confidence: Royal Horticultural Society: Forsythia × intermedia — ultimate spread
Checked 2026-08-13
Time to reach itSourced guidancelow confidence: Royal Horticultural Society: Forsythia × intermedia — time to ultimate size
Checked 2026-08-13

Cutting it back. Breaks readily from old wood, so an overgrown plant can be cut to 45 cm and rebuilt. It flowers on the previous summer's growth, so this costs one year's display whenever it is done — which is why the rolling removal of the oldest third each year after flowering is the better method.

source

Horticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Where and how you can grow it

Each way of growing is assessed separately, and “not assessed” is a real answer rather than a gap we have filled in with a guess.

Method	Suitability	What it needs
Open ground	Well suited source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13
Traditional dug bed	Well suited source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13
Raised bed	Well suited source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13
Container	Marginal source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13

Growing it

PruningPrune as soon as the flowers fade, cutting a quarter to a third of the oldest stems right down to the base. It flowers on wood made the previous summer, so pruning in winter or early spring — the moment when the shrub looks untidy and the secateurs are to hand — removes every flower bud for the coming year. A forsythia that flowers only at the top has been trimmed at the wrong time for years.
PropagationHardwood cuttings taken in late autumn and pushed into a slit trench of gritty soil root without any equipment at all. Forsythia is among the easiest shrubs in the garden to make more of, which is worth knowing before buying a second one.
WateringWater for the first year or two and then not at all. Forsythia is about as tough and self-sufficient as a garden shrub gets, tolerating dry soil, clay, pollution and neglect, and an established one has no watering requirement in a British garden whatsoever. Where a mature plant flowers poorly the cause is nearly always pruning at the wrong time rather than any cultural shortfall — it flowers on wood made the previous summer, so a spring tidy-up removes the entire display.
FeedingRarely necessary. A spring mulch is enough, and a general feed after pruning is worth it only where a shrub has been cut back hard and is being asked to regrow a framework. Feeding will not improve the flowering of a forsythia that is being cut at the wrong time of year, which is what is actually wrong with most of them, and high-nitrogen feed makes the problem worse by producing more of the vigorous leafy growth that tempts people to trim it.

Where this guidance comes from

PruningSourced guidancehigh confidence: Royal Horticultural Society: Forsythia — pruning
Checked 2026-08-13
PropagationSourced guidancemoderate confidence: Royal Horticultural Society: Forsythia — propagation
Checked 2026-08-13
WateringSourced guidancemoderate confidence: Royal Horticultural Society: Forsythia — cultivation
Checked 2026-08-13
FeedingSourced guidancemoderate confidence: Royal Horticultural Society: Forsythia — cultivation
Checked 2026-08-13

The bud you cut to becomes the new shoot, and it grows in the direction it points — which is why an outward-facing bud opens the plant up and an inward-facing one crosses the middle.

The rule is the same in all four: the new piece needs both a growing point and roots of its own. A cutting is the exception that has to make its roots afterwards, which is why the node matters so much.

What goes wrong

Problem	How often	Notes
Capsid bug	occasional source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13

Sources for this page

GrowingHQ editorial synthesis · Plant Finder · Royal Horticultural Society

Each figure on this page carries its own citation, under the “where these figures come from” note in its section. Record last reviewed 2026-08-14.

If something is wrong with it

Healthy growth but no flowers — 2 causes GrowingHQ holds for forsythia

Something else? Work through it with the diagnostic tool.