What flower and vegetable seeds to sow in September for autumn and spring?

In comparison with other regions, our winters in Ireland and across the water in Scotland, England and Wales are considered relatively mild which means there are a lot of hardy flowering plants and some quick growing vegetables you can start now and get growing for a late autumn harvest and early spring colour next year.

So it’s back to where I started this week for me with the seeds out of storage and a bit of indoor sowing once more on what is a rather drab and dreary day.

As well as growing a variety of flowers I also wanted to try and see if I’d have any luck germinating some very old seeds belonging to my late father. He was a keen gardener himself, largely self taught, and a few years after he passed away in 2014 I was given a box with seeds in it belonging to him. I’ve kept that box and had a look inside this year to find seeds dating back over 15 years. Nothing ventured, nothing gained, so I opened a few of them, some radish, spring onion and betroot, all with a use by date of 2012. These are all plants that you can start in the ground now as they tend to be quick growing, like others such as winter hardy lettuce and spinach. Broad beans and some varieties of peas are also very hardy and can overwinter outdoors normally with no problems, as can certain varieties of cabbage and turnips. September is also an ideal time to start planting garlic cloves for harvesting bulbs next year.

Radishes are particularly fast growing can be ready to pull out of the ground in as little as four weeks. Given that the seeds I’ve planted were very old and that the older the seed, the less likely it is to germinate, I wasn’t expecting anything. But the old ‘French breakfast’ radishes have already poked through the soil just days later and the seeds my Da never got to plant are sprouting now. Like most fellows my da was my hero and I hope he’d be happy to see that his seed box is not going to waste.

In terms of flowers you can sow now, there’s quite a few biennials and perennials as well as a few annuals you can get started and grow on for spring while we still have relatively good light. Ideally some you’d be better starting in late July or August and I did sow quite a bit over the last two months such as Wallflowers, Canterbury Bells, Pheasant’s Eye, Hollyhock, Lupin etc, but with others it shouldn’t matter too much as there is still a decent amount of light in September. You could try and get some of them big enough to plant out in the ground or overwinter them in pots either outdoors or in greenhouses or sheds. Some will handle a light frost and some won’t so always do a bit of research.

So what have I planted? Well first up are two blue flowers – Cornflower and Nigella a.ka. Love In A Mist. I’m expecting both will germinate over the coming days and I’ll pot them on initially until I have the flower bed worked over next month so they can get established before the winter sets in.

Next up is the annual Baby’s Breath and biennial Honesty. The Baby’s Breath I sowed a few days ago were from fresh seed just collected from those planted earlier in the year and now going over. And they are already up through the soil, hundreds of them, which is a bit of an eye opener on just how robust fresh seeds are.

In the early summer I sowed quite a few Sweet William and they are well established now and should flower in spring 2025. I thought I’d try a few more now in the hope to extending the flowering season next year.

Foxglove is another biennial you can sow now for some tall spikes of colour in spring and summer and this hardy plant should over-winter fine outside in the ground or in pots. While in the wild they tend to be purple, you can get numerous different colours now from seed shops. But just be mindful that this is a highly toxic plant and not a good option if you have pets or toddlers. Wear gloves if possible and wash your hands after sowing it. This is another new one for me so it will be interesting to see how it develops.

Foxglove is among the plants which benefit from a cold period to get going, and many experts believe autumn sowing makes for tough, bigger plants with more flowers the following year. Some others you can try direct sowing just by scattering the seeds on bare soil at this time of year are calendula and different varieties of poppies such as annual, oriental and California. The seeds may not pop up till spring, but when they do they should grow pretty rapidly.

Next week I’ll be collecting some more seeds from the garden to sow over the coming months and I’ll let you know what surplus seed I have in case any of you would like some free fresh seeds to try yourselves this year or next.