General gardening topics

How to grow bedding plants from seed such as lobelia, marigolds, petunias and begonias

Last updated on March 26th, 2021

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There is nothing quite like an array of stunning bedding plants to add colour to your garden. You can purchase the summer beddings plants at the end of spring usually around April or May, but why head to the nursery multiple times when you can grow bedding plants from seed and have much more fun and the satisfaction of growing yours own?

When you grow from seed you will probably save a little money especially if you already have a propagator, save time shopping around, and gain a wider selection of choice as you can get many more bedding plants types as seeds than you can in trays from even the biggest garden centres.

Sow seeds early around January and February

Most of these bedding plants you can start inside using a propagator in January or February, consider using a heated propagator for a more constant and faster germination rate . The sooner you sow the seeds, the sooner you can get the plants to their flowering stage as this usually takes a good few months. 

super7 self watering propagator is designed to fit onto the windowsill in your home. It features a self watering feature which keeps the soil moist for better germination.

Bedding plants need between 18-21°C to germinate successfully

The key to success is providing the plants with light and warmth, steadily. Most seeds need between 18-21°C to germinate which is why we recommend investing in a propagator if you don’t already have one.

Grow lamps, heat mats, all of these things can help you maintain steady temperatures especially if you are starting early and you can get a good propagator for a reasonable price. 

What you need:

  • Good quality seed compost or multi-purpose compost sieved.
  • Seed tray or small pots or both (7,9 & 10cm are ideal) for however many plants you are propagating.
  • Heated propagator (not essential but advised)
  • Your favourite bedding plant seeds
  • Vermiculite to cover seeds

Prepare the seed tray and pots

With all of your supplies ready, now is the time to fill your seed trays or containers with seed compost. If you use multi-purpose compost then we recommend sieving the compost. Tap each container or seed tray to settle the compost. 

See our recommended multi purpose compost

Sowing seeds

Sowing summer bedding in trays

Space the seeds evenly over the seed tray or containers. Cover them with a fine layer of vermiculite or the compost, a little tip if you cover with compost is to use a sieve or use an empty plastic pot and sieve the compost through the holes.

Label trays and containers

Be sure to label each container or area of your propagating tray so that you know what is growing where. Water the containers well with a fine spray, it’s sometimes better to soak them in a tray if water from the bottom in a tray of water. 

Summer bedding seedling growing in tray

Place inside a heated propagator or onto a warm windowsill

Place the seed trays or pots, what every you sown the seeds in inside your heated propagator. Some kits come with all the things you need including detachable plastic lids which fit over the trays or pots and have vents on top to release condensation occasionally. Set the temperature to 18-21°C is possible, some propagator do not have the option to set the temperature and are usually set to the ideal temperature already.

Make your own little propagator

If you don’t have this, you can make this with a pot and a plastic lid or bag tented over the pot, propped with sticks or pencils to prevent the plastic from coming into contact with the plants.

Thin our seedling into individual pots

Transplanting summer bedding into larger pots

As they grow, you will need to thin out the biggest seedlings from each and move them into slightly larger pots. It is for this reason that you put multiple seeds in a single container. When you place them in a new container be sure to water them regularly and apply a fertilizer every 4-6 weeks thereafter to encourage healthily new growth. This will keep them from drying out and help their early growth.

Plant outdoors around May or later

Osteospermum being planted in rows

Once they are fully grown with their roots systems are established, you can move them outdoors when the risk of frost has passed which is usually May in most parts of the UK.

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