Thank goodness we have done no wildflower seeding here this spring. It has been so dry the patch of unruly wasteland we have in Somerset looks more like the Gobi Desert. I have been watering our green roof and running around the veg patch with a watering can.
I fear this is going to be a pattern; a dry spring followed by a cool wet summer. This is hopeless for seeding wildflower seed mixes. Wildflowers and native grasses are particularly vulnerable because – unlike commercial cultivars – they take a while to get going. They’re also surface sown rather than drilled, which leaves them exposed.
If there’s enough moisture around for seed to germinate the seedlings will conk out before you’ve even noticed them. If there isn’t there’ll just sit there being eaten by birds and blowing about until a downpour washes them away.
Traditional wisdom is that you sow wildflowers in spring or early autumn. Most of the species in wildflower meadow mixes set seed in summer, so you would think early autumn would be a better bet for seeding – and you’d be right.
The idea with seeding in September is that the soil is warm and moist enough and the days long enough that there will be some germination before it turns cold. The caveat to this is to be wary of heavy wet soils, where there is a risk seed will just sit in waterlogged conditions and rot. There’s also a risk of a really wet and cold period on any soil, which would do for a lot of seedlings. Generally, though, it looks to be better time to seed than spring as rainfall is more reliable in September/October than it is in April/May.
Some species too, most notably Yellow Rattle, need to stratify to germinate, so want the cold of winter.
The text books say the last time to seed in spring is end May. This is particularly true of annuals, which won’t have the time to flower before the days start drawing in. If you’re sowing a mix of perennials and grasses – a wildflower meadow mix – I’m increasingly thinking you should think about doing it at any time of year between March and November when conditions are right.
We need to adapt to changing weather patterns and local conditions. If I were seeding a Welsh hillside I would be reasonably happy doing it in June, for example. Rainfall is pretty reliable throughout the summer here. On the other hand I’m increasingly cautious about sowing wildflower mixes in places like East Anglia and Kent in spring without the ability to water.
It looks like we’ll have to take more care whenever we seed. We should also resign ourselves to more failures because of hostile weather conditions. If you have to seed in spring water the seed bed then the seedlings.