May growing with Cel
The spring season feels as though it’s moving on so quickly this year doesn’t it? With warmer temperatures in May, seeds will germinate and develop quickly. It’s a perfect time of year for sowing seeds directly into garden beds as the soil will have warmed up nicely. It’s a good option to have if your greenhouse is overflowing with seedlings!
I’m Cel Robertson and I’m growing the free flower seeds that BBC Gardeners’ World Magazine are giving away this year and I’ll be sharing my progress with you each month. I hope that you’ve been sowing your free seeds along with me and that your sunflowers, echium and strawflowers are growing on well.
- Click here for details of which seeds you can look forward to receiving when.
- Get growing advice now, for all 12 packs of free seeds.
Sow with me
This month’s free seeds are cosmos ‘Sensation Mixed’ and I’ve always found cosmos a fairly easy variety to germinate. The seeds are on the larger side which makes them easy to handle. If you are sowing your cosmos directly into beds, station sow a couple of seeds at 30cm spacings in the border; pre-water the soil so it is moist, make a shallow depression in the soil with a dibber (about 0.5cm deep) and drop in two seeds. Cover the seeds lightly with soil. When the seeds germinate, you can thin them out to a single plant to grown on – just be aware that you may need to protect your precious seedlings from slugs and snails.
You can also sow your cosmos seeds into pots or trays in the greenhouse to plant out into beds as small plants. I’ll be sowing my seeds into small coir pots. I’m going to fill each small pot with peat-free compost and lightly tamp down to firm the compost, and then I’ll stand the coir pots in a flat seed tray to keep them together. I have a dibber with a nice round end, and I will gently press this onto the surface of the compost to make a 0.5cm depression. I’ll drop two seeds into each pot and then cover the seeds with a sprinkle of sieved compost and water.
I would expect the cosmos seed to germinate within 7-14 days, and once the seedlings produce a set of true leaves I will remove the weakest seedling leaving the other to grow on. Once the plant is growing well and the roots have filled the coir pot I’ll plant the whole thing out to minimise any root disturbance to the plant.
Seedling update
Do you remember the free zinnia seeds from the January edition of the magazine? Like cosmos, they are a half-hardy annual variety which means that they won’t tolerate any frost at all and it was much too early in the year to sow them in January. I had hoped to sow my zinnias in April, but we had a couple of weeks of low temperatures so I decided to delay sowing the zinnias until now. I’m going to sow them using exactly the same process as the cosmos and the seeds should germinate quickly in the warmer May temperatures. Zinnias are known for resenting too much root disturbance, so sowing them in a coir pot will help to mitigate that. Hopefully both the cosmos and the zinnias will be ready to plant out at the same time. Both varieties will produce the most flowers when planted in a sunny position.
After sowing a few of the free sunflower seeds in mid-April, I am continuing to sow a few more seeds every two weeks. The first batch have germinated already and will be ready to harden off soon – sunflowers seedlings grow fast and their roots fill the module cells really quickly.
I have been hardening off the echium and strawflowers that were sown in February and March ready for planting out. The process takes about two weeks; in the first week I move the trays of seedlings to sit in a sheltered position on benches outside of the polytunnel during the day, and then I return them to the tunnel at night. Through the second week they are left outside in a sheltered position, and this process helps to ensure that the young plants are acclimatised to outdoor conditions before they are planted out. It won’t be long before I’m ready to plant these seedlings into a flower bed so I’d better do a final weed and spread a layer of compost to make sure the bed is ready to be planted.
- Check out our guide to how to sow seeds indoors
- Read our top tips for how to sow seeds outdoors
- If you’re sowing directly, learn how to warm your soil to give your seeds a head start
- Find the best peat free composts for sowing, growing and more
