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Growing wallflowers from seed

Posted in All Gardening Advice, Perennials and Biennials, June, on 26th January 2011

Growing wallflowers from seed is easy and rewarding.  I’ve just measured a stem from my wallflowers and most are nearly three feet tall. The wallflower plants I’ve been looking at are eighteen inches wide and they’ve been in flower since the second week of March.

There are three varieties, Erysimum ‘Vulcan’, in deep rich crimson-black.I also have Erysimum ‘Fire King’, a lovely sort of browny, toffee-apple orange, and then a bright, magenta-pink, E. ‘Violet’ which is on the verge of pushing Erysimum‘Blood Red’ off the top position. I've grown all my wallflowers from seed.

Here are my top tips for growing wallflowers from seed, including choosing the varieties and caring for your plants.

Step 1: Ideas for how to plant Wallflowers

My Wallflowers are in big blocks all the way down the central path in the cutting garden, lovely tapestry like swathes under-planting an avenue of Stipa gigantea – the golden oat grass. Erysimum ‘Violet’ in particular looks wonderful at the moment with the lovely Lily-flowered tulip ‘Mariette’ in a similar bright-pink, and the freesia-scented, orange Parrot tulip, ‘Orange Favourite’ in a big block at its side. The smell as you walk through the garden at any time of day is as good and sweet as you can imagine.

The key to their visual success is planting lots together in proper drifts – at least fifteen plants of each type, rather than having the dotting of clumps of five or six. I’ve got wallflowers in these smaller groups in the oast garden and they look very ordinary.

So what is the secret to their massive size and success? You’ve got to sow your own and choose the right varieties of seed in the first place. With these three, you’re guaranteed wonderful scent – which some wallflowers no longer have - beautiful colours, and hugely tall, straight stems.

I used to buy wallflowers at the local farm shop. They were always bare-root, ten in a bunch with an elastic band round the lot. I think they were grown on a field scale in the fens as a useful fill-in crop for the summer. They were great – cheap, productive and easy. Sadly, there’s no money in it and the old growers have stopped. The only ones I ever manage to find bare root now are ‘Dwarf Tapestry Mix’ with a maximum height of about twelve inches. As with so many annual and biennial plants, the pressure in breeding programmes is to get smaller and smaller, and yet if you want to pick them for the house this makes them a wash out.


Step 2: Sowing Wallflower Seeds

My wallflower seeds were sown inside in Jiffy 7’s (expanding peat or coir pellets) in early June, then potted on into deep one litre pots and stored on water absorbing capillary matting outside until their space was free at the end of August. I had no room to sow them direct, but if you can find space for a seedbed, you’ll have good germination rates from sowing wallflowers straight into your garden soil. 

Flea beetle – that pin-head, shiny, black beetle, which hops about like a flea – can be a problem with young seedlings. It doesn’t seem to bother them on their capillary matting, but when they are sitting surrounded by garden plants, the beetle may pepper every seedling leaf with holes. It’s not enough to kill young wallflower plants, but it holds them back several weeks.

I learnt a good tip for getting rid of flea beetle organically the other day. It’s the thing that devastates your rocket and a commercial organic salad grower showed me what they did. Get someone to walk along with a yellow fly strip stretched across the line of wallflowers. Follow them close behind ruffling the leaves of every plant. The flea beetles hop up on to the strip and stick!

Step 3: Planting Out

Whichever way you grow them, inside or out, the important thing is to get them into their final flowering position by the end of August. This is about a month before I normally get round to planting any biennial and about a month before gardening convention dictates. In late August the soil is still warm, but the dews have started falling good and thick. The ground is therefore moist enough to not need watering. The roots rocket away and the plants are well established and strong before the night colds really start in earnest in October.

As I planted them, I put the sprinkler on the bed for an hour and then mulched them with a two inch layer of mushroom compost to hold the water in and weeds down. I then spread pea and bean netting horizontally over the whole block in one go, tying it on to canes to stop it dropping down. The netting was stretched taut over all the plants at a height of about eight inches.

If you have a look at wallflowers grown without any support, they almost always lurch over to one side in the wind and rain and then start to grow upwards from their hip. That is one drunken lurch you don’t want. Get them growing straight up and you immediately gain six or eight inches.

Step 4: Plant care

Once you hit mid April, you must keep picking or dead-heading your plants. It’s not so important when the weather is cold, but as soon as you get a few hot days, they will run to seed quickly without a regular shear.

And why not add one other spring-flowering plant, brilliant in combination with all three? It’s another biennial, the purple honesty, Lunaria annua ‘Purple’ which I passionately recommend you combine with them. I’ve got a block of it just behind the stipa and wallflowers and have been picking them and putting all four together in a vase. It’s a rich, velvety, incredibly fragrant, bright, yet faded combination, and what more can you want from flowers?