In October my world is strewn with brown paper bags full of freshly collected seeds, rustling like oversized autumn leaves. The bags, with their turned over tops and black marker pen plant names are spilling over the potting shed benches, of course, but the sales shed has a pile on the desk and some have migrated into the house too. First the utility room gained a little cluster in the corner, but now they have crept into the kitchen too, tucked behind pots of pens, tightly folded and grubby from spending a day in my jacket pocket. They are a comforting presence – a reassurance.


Most of the seeds will be cleaned and stored away in boxes until spring, but I sow some seeds in early autumn. I’ve been asked by many people to explain why I sow some seeds now rather than spring. There’s more than one answer to that question and I’m not always entirely sure why myself. But here’s my take on it…  


1. Some seeds germinate more easily when fresh
Many seeds are easy to germinate when fresh and much harder when they’ve been stored for a few months. Some seeds ‘acquire dormancy’ as they age, protecting them from germinating until conditions are just right. Primulas and Pulsatillas are examples, and many Thalictrums too. All the cow parsely relatives (umbellifers) are best sown fresh too, I’m told. Sown fresh, before the seed has chance to build up dormancy, these seeds can germinate very quickly. I sowed Thalictrum aquilegiifolium ‘Album’ two weeks ago and they are already germinating in my unheated greenhouse. 

These are all hardy plants and I will just leave them in their seed trays over winter. The new young leaves may die down, but if I leave the trays alone, the infant plants will re-emerge in early spring. Once they seem strong enough I’ll pot them up individually and they should grow on quickly.

This little seedling is Sanguisorba hakusinensis. I’m not sure if it really needs to be sown fresh, but it germinates quickly when sown in autumn. Lovely plant – a bit better all round than Sanguisorba obtusa. 

2. Seed that needs a winter chill before they will germinate
Some seeds have a built in seasonal clock which prevents them from accidentally germinating in a rogue mild spell in the middle of winter. They need to experience a longer spell of low temperatures before they can be persuaded that winter really is over. A plant from our latitudes might, for example need to experience 8-10 weeks of average temperatures below about 6C before it will germinate as the spring days warm up. ( I can empathise with that – I feel I need 8-10 weeks of quiet before bounding into another manic season on the nursery!) I digress. 
From reading around and from my own experience, perennials in this group seem to include Astrantias, perennial honesty (Lunaria rediviva), Chaerophyllum and Beesia. 
I sow these in autumn, cover with grit or fine bark and leave them in the unheated greenhouse. If we get a cold, dry-ish spell in January, I might move them outside for a few weeks just to make sure they’ve had a long enough chill before moving them back into the greenhouse in Feb. This group usually germinate in late Feb or early March. 
You don’t have to sow these seeds in autumn – you could put them in damp vermiculite in the fridge for a few weeks, or do it the traditional way and stratify them in a pot with sand. But for me, getting them sown now is a job done once. 
Paeonia mlokosewitschii
3. Slow germinators

I’ve lumped slow germinators of all sorts in this group. Some can need two winters to germinate such as Paeonies. Some produce a root in the first year and leaf shoots in the second year, such as Trilliums. Some are just fussy and will germinate in their own time when they’ve had just the mix of hot/cold/short day/long day exposure.

I don’t bother figuring these out individually and giving them different treatment. I just sow them all fresh in autumn in 3″ pots, top with bark, leave them somewhere cool and shady and hope they’ll get on with it in their own time.
4. Biennials
Sowing biennials in late summer and autumn is all about trying to gain a year. If you collected foxglove seeds in July this year and keep them to sow them next spring, they will produce a leaf rosette in 2015 and flower in 2016. By sowing them in late summer/early autumn 2014 they might grow big enough to flower in 2015.  I’ve sown mine at the end of September which is a bit late really, but if I get a move on they might make it. I’ll probably pot up half of one of these trays in a couple of weeks and leave the rest till spring. 
The thick crop of seedlings on the photograph below is the white biennial foxglove Digitalis purpurea f. albiflora. I’ve also sown a gorgeous white split one from Janet’s garden which has also germinated quickly. We’re hopeful it will come true from seed. 

5. Hardy annuals
You can sow hardy annuals in autumn if you want to. This is a wonderful but little understood group of plants among gardeners. How can a plant be both hardy and an annual? Well, it’s an annual because the plant only lives for a year or less and it’s hardy because its seeds and seedlings can survive the winter. Examples? All of our cornfield annuals such as cornflowers, corncockles and field poppies. Sweet peas, Nigella, Ammi majus, and the gorgeously colouful opium poppies – Papaver somniferum are all hardy annuals.

By sowing now you’ll get an earlier show next year – say about six weeks earlier than by sowing in spring. But autumn versus spring sowing is a topic of hot debate among keen gardeners – a quick look at Twitter if Gardener’s World suggests one or the other is better for sweet peas reveals the strength of feeling among die-hard fans of either approach.

In general, I think sowing hardy annuals in February is just fine. But I sometimes sow in autumn to produce young plants for sale in early spring – especially highly fashionable ones such as Ammi majus and Orlaya grandiflora. 
Books usually talk about sowing hardy annuals outdoors in autumn, but think I lose too many to the birds and especially our chickens. I sow in the cold greenhouse and let them germinate when they will. They will keep growing through mild spells in the winter and may need pinching back to make them nice and stocky for spring planting.

6. Tough, slow growing or bombproof perennials

I sow some perennials in autumn to get them going early in order to make a decent size plant more quickly. I only sow them now if I’m pretty sure the young seedlings won’t be affected by a long cold spell in winter. Also these plants won’t be competing for space in the greenhouse in spring as they will be ready to move out earlier.

So those are my six reasons for autumn sowing. Some plants fit into more than one group. Sometimes I really don’t know, it’s just that autumn sowing seems to me to be the right thing to do.

Finally, for the really nerdy amongst you, the list below is everything I’ve sown this autumn, with one or more numbers from 1-6 next to them, indicating the best reason I can think of to explain why I’ve sown them now.

Aconitum napellus 6
Aconitum hemsleyanum 6
Actaea pachypoda 3
Aquilegia various 6
Ammi majus 5
Astrantia – long petalled form 2
Astrantia maxima   2
Beesia calthifolia 1 and 2?
Cephalaria gigantea 6
Chaerophyllum hirsuitm Roseum 2
Digitalis grandiflora 4
Digitalis purpurea f. alba 4
Gillenia trifoliata 1 and/or 2
Lychnis White Robin 6
Lamium orvale 1 and/or 2
Lunaria rediviva 2
Lathyrus vernus 1 and/or 2
Linum perenne 6
Maianthemum flexuosum 3/6
Meconopsis baileyii 1and 6
Primula elatior 1
Paeony mlokosevitchsii      3
Paeony peregrinans             3
Peucedanum verticillare 1 and 4
Primula sikkimensis 1
Sanguisorba hakusinensis    1and 6
Sanguisorba menziesii 1 and 6
Seseli libanotis 1 and 6
Symphytum orientale 6
Trillium erectum                 3
Thalictrum ichangense        1
Thalictrum diffusiflorum    1
Thalictrum aquilegiifolium 1
Thalictrum rochebrunianum 1
Tragopogon porrifolius 4
Thalictrum osmundifolium 1 (probably)
Thalictrum del. var mucronatum 1
Thalictrun del. var decorum 1

October 11, 2014