Sowing Hardy Annual Seeds in March
Here we are at the weekend of 13th and 14th March and it's prime sowing time for Hardy Annuals (plants that will complete their life cycle within a year and not be killed by the cold early spring temperatures). It's still too cold to sow most of them straight into the earth though and chances are you haven't had time to clear up the flower beds and rake the soil yet anyway. So the best way to get them started is either in a greenhouse or on your windowsill, although you can of course wait to sow direct outside - they'll be a little behind but they'll catch up.
If you're using a greenhouse then your Hardy Annuals will be fine germinating and growing on in there until they're sturdy enough to plant out. If, however, you're using your kitchen windowsill, they'll germinate quickly because of the warmth but then you'll need to get them outside into the light before they stretch towards the window and get 'leggy' (the technical term is 'etiolated'). If you don't they'll be weak and spindly and won't grow into strong, healthy plants. You can't just put them straight out though - they'll need a bit of transitioning into a greenhouse or cold-frame to get them used to being outside before you plant them out when they're big enough in a few weeks' time.
So what to do if you don't have a greenhouse or a cold-frame? You can buy those cheap plastic greenhouses which will do the job just fine as long as you weight them down with sandbags or paving slabs - the taller ones will inevitably blow over in the wind, causing much upset and frantic rescuing of seedlings. You could make a cold-frame - see my first post entitled 'Sow and Grow Some Beautiful Flowers With Me' on how to do this using a wooden crate.
Or you could use lidded clear plastic storage crates which make perfect mini-greenhouses. They're robust, will last for many years and will keep your tiny plants safe from the elements whilst giving them enough light to grow strong. You take the lid off during the day (it's important to stop them overheating in the sunshine - but you can leave it on if the weather turns foul) and put the lid back on in the evening. This helps them get used to being outside, which is known as 'hardening off'. Once the seedlings have outgrown the crates then they'll be fine just pushed up against the wall of the house in a sunny spot. If the weather takes a dramatic turn for the worse (snow, gales etc), you could cover them with a sheet of plastic or pop them in the garage or shed just till the bad weather passes.
If you don't have the time or resources to buy or make something more permanent you could also construct a makeshift and very temporary cold-frame from some garden furniture like I did in the photo below with my garden bench, some string and a sheet of plastic - it's working well and survived the recent high winds and definitely protected my seedlings from destruction in yesterday's hail.
If you're growing on your windowsill here are a few tips to help with successful germination and care until you move them to their next home outside:
- Use the smaller half-sized seed trays - they fit better on the windowsill than the full-sized ones. Or, rather than buy new ones, recycle strawberry and mushroom punnets or the plastic containers that takeaways come in - just remember to make some drainage holes in the bottom (see video below).
- Don't sow all the seeds from the seed packet - you'll end up with far too many seedlings and that makes it harder to keep them healthy. Better to sow fewer seeds and keep the remainder for next year (store in a tupperware in a cool, dry place).
- Sprinkle the seeds sparingly on top of the already damp compost and then check the seed packet to see if they need covering with a very light sprinkling of compost or prefer to germinate without.
- Cover with a clear plastic lid to help keep the atmosphere damp and warm (use cling-film if you have some or pop the seed tray in a clear plastic bag.)
- Once the seeds have germinated, take the lid/plastic off and, if they start to lean towards the light, turn the seed tray around to help them to straighten back up again. Then get them outside into their new home with cooler, brighter conditions as soon as possible.
- Keep the compost very slightly damp and enjoy watching them grow.
- Protect your windowsill with plastic and place your seed tray on a thick layer of newspaper to soak up any excess water.
- Water your seed trays on the draining board and give them a minute or so to drain before putting them back on the windowsill (I speak from experience - I have flooded my windowsills more than once!).
Here's a short video of an easy way to put drainage holes in your takeaway cartons....
And here are my snapdragons and marjoram seeds all planted up in their takeaway containers, lids on until they germinate...
I hope I've explained that all ok. Do let me know if you have any questions. Next time I'll be showing you how to 'prick out' your seedlings into bigger pots and we'll get the dahlias started too. Have fun in the garden.