Rutabaga, or Swede (swedish turnip) – as it’s known in most parts of the world – is a close cousin of turnips and part of the brassica family. It’s sometimes difficult to get this vegetable to a decent size because so many things can go wrong – starting the seeds at the wrong time of the year, certain pests that like to munch on fragile seedlings, and lastly, disease like powdery mildew.

You can certainly take measures to prevent all these nuisances, and one of those important measures is starting Swede seeds indoors or undercover, instead of sowing them directly in the open ground.

Swede seedlings grow even better when sown in modules, safe from harmful insects, frosts, and strong winds. Sow 1-2 seeds per module and thin to the strongest or start them in trays and prick them out a week later into modules. Swede seedlings tend to be leggy but don’t mind root disturbance.

Best time of year to start Swedes

Since they’re a brassica, Swede seedlings are frost tolerant, but that doesn’t mean you have to hurry up and sow them early in spring.

In fact, Swedes have an ideal sowing window in temperate climates. Sow them too early (earlier than mid-April or May), and you risk triggering bolting and rendering your crop useless. Sow them too late (mid-June or later) and your Swedes won’t mature to a satisfying size.

The ideal sowing time for Swedes is late May, a sowing time practiced especially by UK gardeners. You can also get away with two successional sowing times:

  • sow Swedes in mid-April to get a September harvest;
  • sow Swedes in early June to harvest them in October.

If you’re unsure of your climate or have a shorter growing season, experiment with two to three sowing dates and see which plants perform better.

How to start Swede seeds undercover

You can start seeds in a few ways, depending on your preference:

  1. Directly in modules – sow 1-2 seeds per module and thin them out to the strongest seedling, or prick one of the seedlings to move to a cell where seeds haven’t germinated. (Learn more about the pros and cons of module trays vs direct seeding in this article);
  2. In toilet paper rolls – if you’re worried about disturbing the roots system (or if you have tons of loo rolls around);
  3. In trays or small containers – sprinkle seeds all over the surface and cover loosely with soil. You’ll get a ton of Swede seedlings which you’ll then prick out and move to individual modules.

I like to practice option #3 just because I find my indoor-grown Swede seedlings sometimes get too leggy for my liking. Once I prick them out, I can re-pot them a little deeper, but that’s just a personal preference. I’ve found, like many other gardeners, that root disturbance is not an issue – and Swedes are not as much a root crop, as their stems swell at soil level.

Legginess in seedlings has to do with a lot of things, and Swede seedlings are highly susceptible to growing too tall and spindly. You can reduce this tendency if you’re growing them in a cooler setting – like a greenhouse (although June can get pretty hot), or if you’re regularly leaving them outdoors on overcast days. This way, they’ll get hardened off early and prevented from growing too tall.

However, if they still fall over even when they’re ready to transplant – no worries, they’re supposed to look a little floppy. Just transplant them deeper and they’ll do okay.

Can you multisow Swedes?

While you can multi sow turnips and they tend to do well (they’re fast growers and stay small), Swedes are best grown as singles if you want them to reach a decent size.

I love to pack everything as closely as possible in my garden, but I take extra care with plants where spacing is important, and Swedes need a lot of room.

For growing root crops in clumps, I recommend beets – they do very well, as well as radishes and even onions. I’ve written this article on multi sowing that goes into more detail.

When to transplant Swede seedlings outside, spacing and best practices

Swede seeds take about a week to germinate and the seedlings will look very similar to other brassicas at first. When the seedlings are about 1 week old, you have the option of pricking them and moving them to a new pot, if that’s your chosen method. Otherwise, Swede seedlings are ready for transplanting when they’re 3-4 weeks old and have developed at least two sets of true leaves.

You’ll see the seedlings falling over at the base from the weight of the leaves and that’s perfectly normal. When transplanting, use a dibber to create room for the roots and drop them in the ground a little deeper – up to the first leaves.

Spacing is important – if you want to get big Swedes, space them at least 12in (30cm) apart or even more, if you have the room. If you’re happy with getting smaller Swedes, you can plant them 8in (20cm) apart.

By the time the plant is about 2 months old from sowing, it’s time to give them a feed. Swedes, just like most brassicas, are hungry plants, and while they can do just fine with a layer of manure spread in autumn, you can supplement the soil with a handful of chicken manure and seaweed pellets for optimum nutrition.

Let’s talk pests

The biggest reason for sowing Swede seedlings indoors vs in the ground is to shelter them from pests. Since we’re sowing Swedes in May, we’re exposing them to a time when flea beetles are most rampant. Year after year, these annoying bugs munch on radish leaves (and even bulbs!), arugula, and of course, brassica seedlings.

Flea beetles can seriously stunt the growth of Swede seedlings, and if you start seeds outside, they won’t stand the chance when they’re that small. That’s why transplanting a Swede that’s 1 month old gives it a much higher fighting chance against these tiny enemies.

So protect your Swedes from pests by starting them undercover and protecting them with insect mesh from day 1 after transplanting. Mesh covers are also essential if you want to get bigger roots – the indoor-sown Swedes will survive flea beetle and cabbage butterfly attacks, but their growth might get stunted and you won’t get Swedes that are as big.


Hopefully, I’ve convinced you to start Swedes/rutabagas indoors or in your greenhouse instead of an open field. There are so many advantages – from giving them a head start, protection, and correct spacing – not to mention you won’t have any thinning to do. Experienced gardeners swear by this method, and this is what’s worked for me as well. So good luck, and happy gardening!

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