Slugs

Worst in wet, mild conditions through autumn, winter and early spring, March to September.

Slugs are soft-bodied molluscs that feed at night and shelter in damp, dark spots by day. They shred seedlings and leafy greens fast, so a single wet week can wipe out a tray of young plants.

How to identify

• Irregular holes chewed in leaves, often with smooth edges
• Silvery slime trails over soil, leaves and pots in the morning
• Seedlings eaten off at the base overnight
• Slugs hiding under mulch, pots and boards during the day

How to prevent

• Water in the morning so the soil surface dries by nightfall
• Clear hiding spots like loose boards, dense weeds and excess mulch near seedlings
• Ring vulnerable seedlings with crushed eggshell, sawdust or a copper band
• Encourage frogs, lizards and skinks by leaving rough corners of the garden undisturbed

How to control organically

• Hand-pick after dark with a torch, which is the single most effective method
• Set beer traps, sinking a container so the rim sits at soil level and refilling every few days
• Lay boards or upturned grapefruit halves as overnight shelters, then collect and dispose of slugs each morning
• Scatter iron-based pellets (such as Quash or Tui Quash), which are safe around pets and wildlife, unlike older metaldehyde baits
• Apply nematode treatments in damp soil for an ongoing biological knockdown