What is vine weevil, and what else attacks container plants?

Vine weevil is the most damaging pest of container-grown plants, and its defining characteristic is that the damage you notice is done by the stage you cannot see — the grubs eat roots underground while the adults leave only cosmetic notches in leaves.

How to recognise it:

Adults are matt black, roughly 9 mm, flightless, active at night, and cut distinctive semicircular notches from leaf edges. The notching looks alarming and matters very little.

Larvae are creamy white, C-shaped, with brown heads, living in the compost and eating roots. The first symptom is usually a plant that wilts and then collapses despite adequate watering, and by then the roots have gone.

All adults are female and reproduce without mating, which is why populations build so quickly.

What they favour: containers above open ground, and particularly heuchera, primula, fuchsia, sedum, strawberry, cyclamen and begonia.

What actually controls them:

Biological control with nematodes, watered into the compost. This is the most effective domestic option, and timing is what makes it work — apply when soil is warm enough, typically late summer to early autumn while larvae are small, and repeat.

Physical removal. Check pots at night with a torch; tip out compost from affected plants and pick out grubs.

Encouraging predators — birds, ground beetles, hedgehogs.

Barriers and sticky bands on pot rims.

Chemical controls exist and are restricted, with fewer available than previously.

The other container pests worth recognising:

Fungus gnats, whose larvae are mostly harmless but indicate persistently wet compost.

Root aphids, showing as poor growth with white waxy deposits on roots.

Scale insects, immobile brown bumps on stems producing sticky honeydew.

Mealybugs, white and cottony in leaf joints.

Red spider mite, causing fine mottling and webbing in hot dry conditions — raising humidity is the effective response.

Slugs and snails, sheltering under rims and in drainage holes.

The general principle: containers concentrate pests because plants are stressed, isolated and reliant on you — healthy, correctly watered plants resist far better.