Top tips for getting polyanthus to germinate – Brian Kidd

Now is a good time to sow polyanthus seed for spring 2020.
Now is a good time to sow polyanthus seed for spring 2020.
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We must plan ahead if to be successful in the garden. While polyanthus are just starting to bud to explode into flower in a few weeks, we need to sow some seeds now so there are more coming along, even though they won't flower for 15 months.

The great thing about sowing polyanthus seed is that it doesn't need heat to germinate. We don't need a greenhouse either. They will be quite happy sown in a cold frame or even in a cool room because they will germinate anywhere frostproof, but it must be light.

We are used to covering seeds with newspaper and keeping them in the dark to encourage germination, but polyanthus and busy Lizzies germinate far better if left in the light after sowing.

Try to find something special rather than the cheapest packet. This is because polyanthus have been hybridised and there are some superb strains if you’re willing to pay. Read the packets and you might find some which are fragrant. If you like coloured primroses or even wild primroses, the same rules for germination apply.

Polyanthus seeds ripen while still in their seed case. Mother Nature coats them with a thin film of resin which becomes harder over time so the seeds are protected from bad weather. The longer the seeds are left unsown, the harder the resin becomes so by the time the seeds are sent to the shops it's as hard as varnish. This stops them germinating as water can't penetrate the seed coat.

In the garden you might have little polyanthus seedlings growing alongside the parents. This proves they’re easy to grow if the seed is fresh. Prick them out into seed boxes where they will develop into good plants. Only thing is, they may not be as good as their parents as they have been cross-pollinated. This means you will have some of the parents and also some of the grandparents too, not all of which will be brilliant.

I have found a way around the problem of the resin. Take a screw-top jar and put a teaspoon of dry sharp sand in it. Now put the seeds in and replace the lid tightly. Shake the contents for five minutes and then sow on any seed compost in a tray or pot. They should germinate in two weeks in cool, light conditions.

The seeds must be saturated, not just damp, so try this. Once the seeds are sown, soak the seed tray in Copper Mixture. This will kill off fungal diseases and help prevent damping off, the disease which causes seedlings to keel over. Having really soaked the compost, cover the seed tray with Clingfilm.

Inspect every day to see if they have germinated. Once they have, remove the Clingfilm but put the seed tray into a slightly deeper box and cover it with a sheet of glass.You will now be proud you have the best-ever germination of polyanthus.

Once the seedlings are large enough to handle, prick out each one into insert trays. The one with only 12 cells is the best so the plants have space to make a super root. The larger the root, the more flowers you will have in spring 2020.​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

THIS WEEK’S TOP TIP

Planning to sow a few seeds in the greenhouse? Ensure the propagator is turned on for 24 hours before sowing. Remember too, a section of greenhouse can be kept warmer by using polythene bubble plastic to divide it.