How do I stop my pots blowing over?

Why tall plants in light pots go over, and the weight, shape and shelter changes that keep them upright without moving everything indoors.

Difficulty: beginner
Time: 30 min
Read: 3 min

Short answer

The problem is almost always a top-heavy plant in a light plastic pot with a narrow base. Add weight low down — loam-based compost, stones or paving slabs in the base of a large planter — widen the base, and move the tall pots into a group against a wall.

A pot that blows over usually breaks, damages the plant and often takes a pane or a light with it. It is worth solving before the first autumn gale rather than after it.

Step by step

Switch to loam-based compost.A loam-based mix weighs roughly twice what a peat-free multipurpose does when moist. For anything tall this is the single most effective change.
Choose pots that are wider than they are tall.A tall narrow pot with a small base is unstable by design. Where a plant needs height, put it in a broad, heavy container instead.
Weight the base of large planters.A few large stones, a broken slab or a bag of gravel in the bottom of a big planter lowers the centre of gravity. Keep the compost depth adequate above it.
Group pots together.Pots wedged against each other cannot fall. A cluster in a corner is far more stable than the same pots spread along an exposed edge.
Put the tall ones against a wall.Backed by a wall or fence, a pot can only fall forwards, and often cannot fall at all if others are in front of it.
Tie tall plants to something fixed.A standard bay, olive or acer in a pot can be tied to a wall vine eye or a trellis. It is invisible and it is permanent.
Cut back top-heavy growth before winter.Reducing the sail area of a tall shrub or grass in late autumn reduces the force acting on it. Do not do this to plants that flower on old wood.
Use pot feet, not a saucer, in winter.Feet keep drainage working. A waterlogged pot is heavier, but a frozen waterlogged pot cracks, and the plant dies anyway.
Move the vulnerable ones for a named storm.Laying tall pots on their sides in a sheltered corner for two days is quicker than replacing them.

Tips

Loam-based compost is the cheapest ballast there is, and it is also better for the plant.
Pots grouped together hold each other up.
A standard tree in a pot is a sail. Tie it to a wall eye and forget about it.

Common mistakes

Putting a tall shrub in a tall narrow pot because it looks right — The proportions that look elegant are the ones most likely to go over. Wide and heavy at the base is what stays upright.
Weighting a pot by standing it in a full saucer of water — It adds little weight and waterlogs the roots. Weight belongs in the base of the pot, not under it.

If it doesn't work

Same pot goes over every autumn

Cause: Top-heavy plant, light compost — Fix: Repot into loam-based compost in a wider container, and move it against a wall.

Pots knocked over on a balcony

Cause: Wind accelerating around a corner — Fix: Group them, weight them, and fix trellis or windbreak netting to filter the wind.

Terracotta cracking as well as falling

Cause: Frozen waterlogged compost expanding — Fix: Raise on feet, remove saucers, and move the vulnerable ones under cover for winter.

Plant blown out of the pot, roots exposed

Cause: Insufficient rooting depth for the height — Fix: Pot on into a deeper container and stake or tie the plant while it re-establishes.

Questions people ask

Will putting stones in the bottom help?

For stability, yes, in a large planter — weight low down is exactly what you want. Note that it is a stability measure, not a drainage one; a stone layer slightly worsens drainage.

Should I bring pots inside for winter?

Only the tender ones and the most vulnerable containers. For everything else, grouping against a sheltered wall and raising them on feet deals with both wind and frost.

What compost is heaviest?

A loam-based compost. It weighs roughly twice as much as peat-free multipurpose when moist, holds nutrients better and rewets more easily.