The secret step to starting seeds

Also known as ‘A winter in September’.

Oh, that crushing crushing disappointment of an empty seed tray. All the excitement and the investment and the buying (or saving, please save) of seed and then… nothing. 

This is the second reason why I do worry about people saying that gardening is good for your mental health. Is it possible to feel rejected by a strawflower?

If you are interested, the first reason is slugs. 

Heartbreak in a mollusc.

I think one of the issues is we are too nice. My dogs are currently asleep on the sofa, you don't need to tell me I'm a soft touch. We are heading into the last week of September and I'm thinking about the cold, wet soil, and there's no way I'm risking my beautiful, precious seeds in that. They will be tucked up in a blanket of eye-wateringly expensive organic, biodynamic compost and in my greenhouse. I will check them twice a day, move everything around to bottom water them, and watch carefully for the aforementioned slugs.

And you know what? Some of the annuals will be fine. Annuals are the Labradors of the flower world; generally enthusiastic and bounding into life without a huge amount of effort on anyone else's part. But the really precious ones? The ones I persuaded Jelitto to post from Germany? The perennials need something else. Not rocket science really, they need cold.

It has taken an embarrassingly long time for me to catch on to the importance of pre-chilling seeds. Some plants won't germinate—or will germinate poorly or irregularly — unless their spring follows a prolonged period of cold weather. 

You can either do this by sowing them into the ground in autumn and hoping for a few good hard frosts (I just can't), or you can fake it with a fridge.

This process is called cold stratification, but I think between us, we're going to call it pre-chilling.

WHAT

 List of plants that would thrive with chilling:

• Anemone

• Aster

• Astrantia

• Baptisia

• Bells of Ireland

• Campanula

• Celosia

• Clematis

• Columbine

• Cornflowers

• Delphinium & larkspur

• Dicentra

• Echinacea

• Eryngium

• Globe thistle

• Hollyhock

• Honesty

• Joe Pye Weed

• Nigella

• Phlox

• Poppies

• Primrose

• Rudbeckia

• Rudbeckia

• Sanguisorba

• Scabiosa

• Sea Holly

• Snapdragons

• Strawflower

• Thalictrum (meadow-rue)

• Verbena hastata

• Viola

• Weld

And which won't:

If the seed you have in your hand doesn't come with instructions, there are two questions you can ask yourself.

Firstly, if it is a perennial, the chances are it will benefit from pre-chilling.

Once you have answered the perennial or not question, there's only one other thing to thing; does it come from somewhere super hot, where winter isn't really a thing? They aren't going to need chilling. Dahlias from seed for example. They wouldn't know what to do with a winter.

TIMING

I am cutting it fine by thinking about this in September. Although I did get my larkspur in the freezer in good time, I am a little late with everything else. This is because the extra fortnight means you don't start the pre-chilling on the sowing date for that seed, you have to add it on.

For example, there are some flowers that are more August-September than they are September-October, and I have missed the boat on those.

We will be doing this all over again in the spring and I will be far more organised. There is also an easier firm date with the last frost date which makes this a bit easier to explain. The last frost is around April 21st here, which means:

4 weeks before this last frost is March 21
8 weeks before this last frost is February 21

If the guidance is to sow eight weeks before the last frost, I had better start the fortnight's pre-chilling ten weeks before (February 7th).

HOW

COLD ONLY:

Place seed packet or the number of seeds you want straight in the refrigerator or freezer. This method obviously requires the least effort but sadly, I don't generally recommend it. This is because pre-chilling usually required moisture and cold to trigger the whole process of coming back to life. I mean, I keep my seeds in a seed fridge (cold and dry) before I post them to you for the express purposes of keeping them dormant.

The one exception: Larkspur. Just chuck the whole parcel in the freezer for a week.

COLD & MOIST: 

Wrap seeds in a moist paper towel and place that paper towel in a sealed bag or a Tupperware box. I find the bags quite fiddly so this year I am doing folded over kitchen paper wraps (remember to include a label with writing that won't run) all stacked on top of each other. Then put the whole box in the fridge and write a reminder in your diary for two weeks hence.

I have said two weeks because that seems to be enough the vast majority of seeds, although some (Astrantia for example) seem to want four to six weeks.

Until I have spent January researching every single perennial cut flower and making notes on their individual needs (and I promise I will share it all with you in an easy to reference printable when I do) I am going to opt for the two-week window.

I did read one suggestion that Rudbeckia should be a day in the fridge and then a day in the freezer, alternated for a month. Have I got the capacity for that?

COLD + MOIST + SOIL: 

Mix seeds with a moist soil mix or vermiculite of some kind. Wrap in scrap fabric, paper towel, or place in a Ziplock bag. Place this in the refrigerator or freezer.

This method requires the most faff, but it gives you the benefit of more water retention than the paper towel method. If the seeds are very small, it can be difficult to sort them out in the soil to know how many you're planting or to surface sow. And it doesn't matter what you put the moist soil or vermiculite in, it will stick when you try and get the seeds out. I'm not going to try this one, so let me know if you do.

If this is all seems too much, remember, you can just direct sow in autumn. A compromise position is in 9cm pots that you leave in an exposed and chilly position. This always feels better that direct sowing, but pots attract slugs so…

 A little note on moisture

This really is a bit tricky. Too dry and the seed either won't chill or the coat won't soften enough. Too wet and it will rot or go mouldy. We are going to for moist. The guidance is generally that, if you squeezed the kitchen paper with your hand, nothing would drop out, but it would stick to itself like paper mache. Not terribly easy to judge but do take it seriously.

WHAT NEXT

After two weeks, unwrap the kitchen paper parcel and take each individual seed and put it into a module tray with seed compost. Water from beneath and put somewhere warm.

This year, I am going to try germinating some directly in the paper towel, which means just putting the whole thing (unwrapped if the seeds need light) in a Tupperware box on the kitchen windowsill. Once the seeds have sprouted, they can be moved one by one into the modules with tweezers.

Oh, so much faff, but watching each one send out a little shoot will make October for me. If I can get a chocolate soldier aquilegia to germinate, it'll make my year. 

I'm doing all of this tomorrow - let me know if you are trying it too.