Well, another glorious weekend has come and gone and we've enjoyed some wonderful family pottering about in the garden. John's been mowing (he loved a mow!), Imogen's been watering (her feet, the log pile, occasionally some plants) and I've been hard at work creating the new lavender bed at the front of the terrace. It's a very, very sunny spot with free draining soil so perfect position, but as it was entirely grass and weeds I had to do a little bit of preparation first! I removed the turf with a spade and stacked it at the back of the shed under a tarp, it will rot down nicely to create lovely rich loam which will be perfect for adding some nutrition back into our poor soil. Then dug, and dug, and dug some more, removing dandelion roots as I went. Finally I edged the beds with some old fence boards and gave everything a good rake, before planting the lavenders. They're all English Lavender, half of them are two year old plants and half new babies. I've spaced them about 50cm apart to give them space to grow, but will fill in the gaps with cerinthe and scabious this year so it doesn't look too bare.
Now is the perfect time to get out into the potting shed and start sowing seeds like cerinthe and scabious for the summer. Hardy annuals and veg can all be sown now, and if you have the greenhouse or coldframe space you can get a head start on more tender things like tomatoes and dahlias. A little bit of attention to detail now will pay dividends at harvest time, so to get seed sowing right there are a few things you need to bear in mind.
1. Condition of seeds
All seeds need to be kept dry, dark and cool. A tupperware pot in the fridge is perfect, especially if you pop one of those little silica gel packets in to absorb any excess moisture. Some seeds like to be stratified before they'll grow, tricking them into think they're growing in their natural position, seasonal temperature changes and all. You should also pay attention to the shelf life of the seeds. Some, such as astrantias or hellebores, have to be sown fresh; in these situations it's often easier to pop a little tray of compost under the plants in the border and just let them self seed. Some others can be stored for several years - I currently have some 'sow by 2014' peas germinating beautifully on the windowsill.
2. Growing Medium
All seeds need compost, but not all composts are created equal. It's important that the compost is light and free draining, specific seed composts are perfect. If you haven't got any then sieved general purpose compost with a healthy dose of vermiculite mixed in will do the trick, but given as you'll probably only need one bag, it's worth the investment. A seed compost will be sterile, loose enough for tiny roots and not contain too many nutrients that might damage your seedlings.
A general rule of thumb for the placement of seeds is to sow them twice as deep as they are wide. Tiny poppy seeds are just sprinkled thinly on the surface and covered with a sprinkling of vermiculite, big broad beans pushed deep into the pot. Wide, flat seeds such as pumpkin seeds should be planted on their side to stop water collecting on the surface and rotting the seed.
Make sure you lightly tamp down the compost after sowing - if a root hits an air pocket it won't be able to grow. Some tougher seeds like sweet peas benefit from a brief soak before sowing, though some gardeners recoil in horror at this idea.
The smaller the seed, the more delicate the seedling is likely to be. In these cases then using module trays is ideal - sowing a couple of seeds (pick them up using a damp cocktail stick) into each square and then only potting on when the roots are poking out the bottom. Tougher things (scabious, cerinthe etc) can be sown into larger pots and then pricked out into their own 3" pots when they're big enough to handle. Once they've filled those they can be planted into the bed.
Some plants really hate being moved. In these cases it's best to sow directly where they are to live and to protect them from any mad spring weather with cloches or mini polytunnels. The exception to this may be sweet peas, which do surprisingly well when started off in root trainers, which are fantastic for getting them started inside.
5. Light & Water
Most seeds like to be warm and light to germinate, but some odd balls need to be cool and/or dark. It will normally say so on the packet, so if in doubt a sunny windowsill (or greenhouse) will be perfect.
It's absolutely vital that you don't let your seedlings dry out, it might look like nothing's happening but if your seed is germinating under the surface and doesn't have enough moisture, it will die before it even gets a chance. I water mine every morning, and sometimes in the evening too if it's been a very sunny day. The compost needs to dry (too boggy and the seedlings will rot) but not dry out between waterings, watering from the bottom is always a good idea.
And that's it. It's really not too complicated, just keep those seedlings watered with plenty of light and pot them on if they get too big. Tender seedlings can be hardened off (gradually increasing their outside time every day) and planted out after the risk of frost has passed. That's the beginning of May down here in Devon, but will be later further North. Good luck and I'd love to see the results!