Slugs eaten your summer greens? Plant brassicas now for an autumn yield

Even though my veg patch is – mercifully! – full of crops ready to harvest, there are some notable absences caused by this having been the year of the slug. Along with lettuces and the first round of climbing beans, brassicas have been repeatedly mown down by the molluscs that munch their way through my garden. I’ve missed the reliable sight and taste of kohlrabi, kale and the (usually) ever-reliable ‘Red Russian’ kale. Fortunately, we’ve reached the time of year when you can begin to sow seeds for an autumn harvest – one that will take you through the leaner winter months to next spring.

Kohlrabi is relatively straightforward to grow, and because the purple-skinned varieties are hardier than the paler ones, they are the best choice to sow now, as the temperature will be dropping by the time they’re ready to harvest. Cavolo nero is my preferred variety of kale and I’ll be sowing seeds in coming weeks so that the plants are a decent size by the time the days shorten and they stop growing. (Come the first signs of spring, they’ll be back in action and provide one of the earliest harvests of the new season.) The more tender-leaved ‘Red Russian’ kale and spicy mustard greens – including varieties such as mizuna – will also make it through winter as long as the plants are established before colder weather arrives.

I start all these brassicas in modular seed trays, sowing one seed in each module for the cavolo and kohlrabi and about three or four seeds a module for ‘Red Russian’ kale and mustards. The soil is warm enough to start seeds in the ground, but I’m certain slugs would find their emerging sprouts if I attempted that. If your seed trays are in a greenhouse or covered space that really warms up, keep on top of watering and consider moving them somewhere cooler on hot days, as they may bolt if stressed by the heat.

Cabbage white butterflies will be active until October, so protect plants from the moment there’s enough leaf for them to lay eggs on. You’d be surprised how capable of sneaking under insect-proof mesh these butterflies can be, so check the underside of brassicas’ leaves for little yellow eggs (or for caterpillars if you missed the egg stage) regularly.

Related: Sow chicory and radicchio this summer to brighten your plate (and garden) in winter

I tend to leave the mesh in place (or replace it with fleece) as the weather shifts to offer an additional layer of protection, as hard frosts can be fairly destructive even for the varieties described as hardy. The flavour of cavolo nero is believed to improve once exposed to winter weather, yet I’d still be tempted to throw fleece over it if snow is forecast. After the bizarre weather we’ve had this season, that might come sooner rather than later!