Slugs Are Destroying My Cabbage Seedlings

Cabbage seedlings are most vulnerable to slug damage in the first three to four weeks after transplanting — when they are small, the leaves are tender, and the soil disturbance of transplanting creates the moist, loose surface conditions that slugs prefer. A slug attack on newly transplanted cabbage seedlings can reduce a tray of carefully raised plants to bare stalks within two or three nights in wet spring or summer weather. The key is protecting the plants through this critical window until they are large enough to be less severely affected by slug feeding.

Why transplanting creates slug vulnerability

Transplanting disturbs the soil and creates the ideal conditions slugs need — loosened, moist soil around the stem where they can shelter during the day and feed at night. The transplant stress means the seedling is not growing vigorously and cannot outgrow slug damage quickly. Any slug that finds the seedling can cause significant proportional damage because the total leaf area is so small. Within two to three weeks, if the plant has established and is growing away strongly, it has enough leaf area to absorb a similar level of slug feeding with much less impact.

Ferric phosphate pellets

Ferric phosphate slug pellets (sold as Ferramol or similar) are approved for organic use and are safe for wildlife, pets, and birds — the iron phosphate is broken down to soil nutrients after the slug is killed. Apply sparingly around newly transplanted plants immediately after planting. Refresh after rain (the pellets dissolve in wet conditions). These are the most practical chemical control for the establishment window.

Physical barriers and hand removal

A collar of copper tape around each individual transplant deters slugs from climbing up (not foolproof but worthwhile). Copper impregnated mats or wool pellets create a surface slugs avoid crossing. Nightly torch inspection and hand removal during the first two weeks is highly effective — a ten-minute check on two consecutive evenings after transplanting can remove most of the slug population from a small planting. Use a bucket of salty water to kill collected slugs, or transport them far from the garden.