Hartley Magazine

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Slugs in the greenhouse

Now here’s a sight to strike fear into the heart of any greenhouse owner. The greenhouse is full to bursting with healthy young plants, all waiting to head out into the allotment. Despite a few false starts and a couple of non-germinations it has been a productive spring, most things were sown around the correct time, and grew as they were meant to and there have been no major disasters.

The kids – as far as I can tell at this stage of the game – have abstained from random label swapping. Nothing went outside before the cold snap, a happy coincidence of slatternliness and luck. The greenhouse table and floor are both now carpets of green, rows of perfect little plants awaiting the moment when it is warm enough to go outside, or I have cleared enough space to plant them, and hopefully both. And then I walk in this morning and see a gap, a circle of brown compost where once there were two perfect, round leaves of winter squash ‘Crown Prince’.

mayActually, not a complete circle of compost, a little stump of (presumably unappetising) stalk has been left behind, and a giveaway slick of silver. It didn’t take long to find the culprit and his friend: sitting patiently on the bottom of a seed tray alongside were two small slugs, presumably waiting for nightfall and feeding time, when they could more safely nip out and start on the next pot. I was lucky they were only small and that I got to them quick.

A slug in a greenhouse is a thing you don’t want, at this crucial moment above perhaps all others. So this is a good moment to set up a full scale search, and then get a strategy in place to discourage them. First things first: I lifted every pot. I found a good few other lurkers and evicted them, snails too of course. I checked nooks and crannies as best I could and think that I am now, at least temporarily, slug and snail free.

Next step is to keep out any more, to which end I sprinkled organic slug pellets along the entrance and a few around and about the greenhouse. I placed some grapefruit halves upside down in a few places (they love to lurk in these dark, damp, acidic hollows) and have left a couple of limp lettuce leaves lying around.

Slugs actually prefer slightly wilting greenery to young and fresh seedling tops, so if I can throw a bit of this down every few nights I might be able to sate them before they hit the cucumber seedlings. Above all though, I need to be more vigilant. If they are going to lurk until dusk then after dusk I need to be out there, torch in hand, giving them the evil eye and being ruthless in my dispatch. Just before bedtime seems as good a time as any, when they are all out in the open and confident they wont be disturbed.

There are a couple of other things I could try but haven’t so far. One of the best ideas I’ve seen for a greenhouse is to use copper tape wrapped around all of the uprights of the tables and benches. Slugs hate to travel over copper, but in the garden it can be tricky to make use of this. The greenhouse suits it perfectly. I could also tape a couple of slug pubs to the legs: plastic milk bottles with holes cut in the side and filled with beer. Slugs find it irresistible and climb over the lip and drown. Both of these techniques seem particularly suited to the greenhouse, and both may well be added to my armoury, to try to keep those plants intact until they get outside.