5 flowering plants you can collect seeds from right now to fill your summer garden with bold blooms for free

We may be heading into the cooler months, but this doesn’t mean you should put your gardening gloves down just yet. In fact, it’s time for one of the year’s most fun gardening jobs: collecting seeds ready to fill your garden with beautiful colours next growing season.

Collecting seeds from your garden is not only a fun job to complete, but it’s also an incredibly rewarding way to fill your garden with stunning blooms for free! Of course, you’ll need to know how to collect seeds from your garden, but once you do, this autumnal task will save you plenty of time and money from going to the garden centre.

Now is one of the best times of the year to collect seeds, as many plants come to the end of their growing cycle, and garden experts say these are the 5 best plants to collect seeds from now.

1. Cosmos

First on the list is cosmos, a gorgeous summer-flowering plant that will fill your garden with bold hues come the summer months. And right now it's the prime time to collect seeds so you are ready to grow cosmos come spring.

‘September through to October is the perfect time to collect seeds from your cosmos plants,’ explains Lucie Bradley, garden expert at Easy Garden Irrigation.

‘When the petals have fallen from the flowers and the seed heads dried and gone brown, is when you should rub the heads to get the seeds to fall into your hand. You should then be able to separate the dark seeds from any other debris and place them into a paper bag or envelope ready to store.’

2. Sunflowers

With huge yellow heads, sunflowers are a sure fire way to add joy to your garden border ideas. But not only do they frame your garden beautifully, sunflowers are great food sources for your local wildlife, so make sure you leave a few seeds for the garden birds!

‘You can tell when sunflower seeds are ready to harvest as the flower will have turned brown, the seeds appear plump, and the seeds should come out easily,’ says Richard Barker, commercial director of LBS Horticulture.

‘To harvest the seeds, cut the flower from the stem and remove the chaff. The chaff can drop off by itself, but you may need to remove it manually to expose the seeds.'

'Mature sunflower seeds should come away from the flower easily when you rub them with your finger, but if this does not happen, then they will need more time to mature. If this is the case, leave the flower to dry out for a little longer, and check the seeds again in a few days.’

3. Dahlias

Dahlias are some of the most popular plants out there, famed for their show-stopping petal formation and bold, bright colours. You can grow dahlias from seed if you collect the seeds now, ready to be sown between February and April.

‘Easy to handle, dahlia seeds are a bark brown or black oblong shape, approx. 1.3cm long. These seeds are in seed pods which form once the dahlia bloom fades and dries, which you will see happening in September through to October,’ says Lucie.

‘The simplest way to collect dahlia seeds is to snip off the full flower head once it has turned brown and dried out. Leave the collected heads to finish drying somewhere warm and dry for about 10 to 14 days, when you can then break up the seed heads to get at the long dark seeds ready to store until it’s time to plant next year.’

4. Zinnias

Zinnias are sun-loving plants, beginner-friendly and produce some of the most Instagram-worthy blooms in the garden. Once you’ve mastered how to grow zinnias, you’ll definitely want to start collecting their seeds to enjoy these beautiful flowers for summers to come.

‘Once the flowerhead has faded and dried, you can collect the seeds from zinnia plants (as long as it is not a hybrid variety). When the seeds have ripened to a dark brown, you can cut the flowerhead off the plant,' explains Richard.

'Hold the flowerhead over a piece of paper, and agitate it gently or hit it against the surface of the paper to remove the seeds. Discard any petals and then leave the seeds to dry out for a few days.'

5. Marigolds

Marigolds are a superhero plant. Beautiful to look at and naturally repelling pests, it’s a plant you definitely want to keep in your garden.

‘Resembling a fine pointed sliver or stick, marigold seeds have a very dark brown lower half, whilst the top half will be very pale yellow or white and feathery at the end,' says Lucy.

'These seeds are tightly packed into the seed pod of the marigold flower and are ready to collect once the flower petals have faded and fallen off and the remaining seed pod has dried, turned brown and starts to droop on the stem, indicating the seeds are mature.'

‘Simply snip off the seed pods and place them into a paper bag and leave for a few days somewhere warm and dry to ensure they are completely dry.'

'You should then be able to rub the seed heads between your fingers to release the tightly packed seeds. Once released, leave to thoroughly dry before storing.’

Will you be collecting seeds from your garden this autumn? We'd love to know how you get on.