Everything you need to know to grow flowers from seed – and five of the best to try

Telegraph

21-02-2025

For the past 30 years I have spent each spring obsessively sowing flower seeds. It all started in my 20s when I was working for Gardens Illustrated magazine and managed to get an allotment at Fulham Palace in London. Sharing a full-size allotment plot with my cousin, I instantly became hooked on growing, and despite stringent rules stipulating that most of the plot had to be devoted to food crops, I was always keen to have flowers too. That first spring, having cleared and planted about three quarters of the plot with veg, I ran out of time, and scattered Californian poppy seeds over the remainder of the cleared plot to see what would happen.
Three months later I arrived to find those beds aflame with colour. It was magical, and it felt so good to have grown these magnificent flowers from a packet of tiny seeds. So began a quest to grow more and more flowers from seed each year, to seek out new and exciting varieties that couldn't be found elsewhere, and to experiment with growing methods to get the best results. There were huge triumphs along the way, but also many failures, which I tried to learn from the following year. The main thing to know is that growing from seed is easy. Mostly, these seeds want to grow for you and will germinate readily if you give them the conditions they need. Choose some of the most easily grown annuals listed below, and you can almost guarantee your success.
Why should we be growing from seed?
If you have ever grown sweet peas from seed, watching them germinate and nurturing them until they flower, you will know that particular sense of joy and satisfaction that comes from sowing seeds. To me, growing from seed is a sort of therapy. The quiet, meditative act of sowing and growing is a marvellous antidote to the stress and strains of everyday life. It connects you with the seasons, it makes you observe the minutiae of a plant's form and gives you an understanding of nature. The evolution of a beautiful flower from a tiny, unpromising seed is one of life's miracles, and to have a hand in that is amazingly rewarding.
The other major reason for growing your own flowers from seed is the incredible range of varieties you can find. With annuals in particular, only a very small range is available to buy as plants in nurseries and garden centres. Once you start realising the wealth of interesting and beautiful flowers available to grow from seed, the plant world opens up considerably. Each year, as I browse through the seed company websites, I am like a child in a sweetie shop, excited by new varieties I haven't come across before.
And last but not least, growing flowers from seed can save you money. As well as annual flowers, you can grow perennials that are sold as plants in garden centres for £10 or more. If you need multiple plants, it can become an expensive business. Sowing a tray of 12 Verbena bonariensis, for instance, with a packet of seed that costs £3.95 (plus the cost of a bag of compost) is far, far cheaper than buying them as two-litre potted plants.
Tips and techniques
Everyone can grow flowers from seed. The main thing is to be quite laid-back about it and not worry about doing things exactly by the book. Over the years, I've found that you can often take received wisdom in gardening books with a pinch of salt and adapt techniques to your own circumstances. However, there are a few things you can do to maximise your success:
Sow as much as you can in seed trays rather than direct. Sowing direct is more risky as the seedlings are at the mercy of the weather and wildlife.
The majority of plants need a temperature of 18-21C to germinate, so keep them somewhere warm until you can see the first signs of germination. This could be over a radiator on a windowsill – you don't need a special propagator. Then move them to a cooler place straight away. If you give them too much heat as the seedlings grow they will become leggy and weak.
Use a fine, good-quality compost designed for sowing seeds, especially for tiny seeds such as foxgloves and tobacco plants. For larger seeds you can use a coarser multi-purpose compost, but make sure you remove large lumps of organic matter first.
Read the seed packet for specific instructions. Some seeds need light to germinate, while others don't, and this kind of information should be printed on each packet.
Use modular seed trays with individual compartments, rather than open seed trays for larger seeds – it saves having to prick the seedlings out afterwards.
Keep seedlings well-watered using a small watering can with a fine rose so as not to damage them.
Pot on the seedlings into larger pots until you are ready to plant them out. If they remain in seed trays or small pots for too long, the nutrients in the compost will run out and the seedlings will start to droop or look etiolated. They can also become pot bound, so getting them into the ground as soon as the soil is warm enough is a priority.
My top 5 easy flowers to grow from seed
In my new online course with Create Academy, I've detailed some of the flowers I love to grow from seed. Here are five of my favourites:
Ammi majus, Bishops Flower
Ammi majus is one of the most useful annuals of all. A more subtle form of the common cow parsley, it can grow up to 1.6 metres, with lacy flower heads that are fantastic for cutting and arranging. Easy to grow from seed, it can be sown in both early spring or autumn; the autumn-sown plants flower earlier and produce taller and sturdier plants than those sown in spring. Sow the seeds in a modular seed tray with several seeds to a cell and remove the weaker two seedlings once germinated. Germinate at a temperature of around 18C. Grow the seedlings on until they are big enough to be planted out in mid spring – they are really hardy, so they can go into the ground earlier than many other annuals.
Calendula officinalis, Marigold
All calendulas are very easy to grow from seed. I love the creamy white 'Snow Princess' and the pale apricot 'Orange Flash'. The seeds are the type that just want to germinate for you, whether sown direct or in modular trays. Sow indoors from early spring, and outdoors in mid-spring when the soil has warmed up. Marigolds aren't fussy about the soil they grow in, and will grow in full sun or partial shade.
Cosmos bippinatus, Cosmos
Cosmos is possibly my favourite summer annual, easy and immensely satisfying to grow. My favourite varieties are the deep cerise-red 'Rubenza' and the frilly 'Psyche White' and this year I'm trying a new one – 'Rosetta' from Chiltern Seeds. Sow cosmos seeds under cover in April, two seeds to a module, and they should germinate quickly at 18-21C. Remove the weaker seedling and let the stronger one grow on, pinching out the growing tips if they get too tall (this causes a multi-branching effect making bushier, sturdier plants). Don't plant them out until after the last frosts as they are tender annuals (known as half-hardies).
Lunaria 'Corfu Blue', Honesty
Honesty is such a useful plant for early spring, an easy companion for tulips and euphorbias. Most forms are biennial, flowering in their second year, but they self seed freely to weave their way languidly around other plants. 'Corfu Blue' is a particularly good variety with purple-blue flowers and a multi-branching habit. Flowering in early spring, it forms purple-green pods that remain on the plant through summer, autumn and even winter, fading gracefully as time goes on. Collecting and sowing your own honesty seed is one of life's pleasures. As biennials, the best time to sow them is in early summer, either direct or in modular trays, where they can stay until the end of the summer, when they should be planted out in the garden before flowering the following year.
Zinnia elegans
Zinnias bring exotic colour to our gardens and are extremely easy to grow from seed. There are dozens of varieties to choose from, in single, semi-double and double forms of varying size, and in pretty much every colour apart from blue. My current favourites are the 'MFG Perfectly Pastel' mix from Marlston Farmgirl and 'Queen Red Lime' which has dusky red and lime flowers like antique chintz. Zinnias are fussy about having their roots disturbed, so sow them in modular trays so you can plant them straight out with minimal disruption. As half hardies, they shouldn't be sown too early, otherwise the seedlings will fill their modules before the last frosts. They need temperatures of 20–23C to germinate, then move them to a slightly cooler place once the seedlings have emerged. Plant them out in early summer in as sunny a spot as possible.