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Plant Now for a Colorful Spring: Flowers to Sow in September

Plant Now for a Colorful Spring: Flowers to Sow in September

Nicole Hutten |

September might feel like the winding down of the garden season, but for flower lovers like us, it's just the beginning of something beautiful. While the focus might be shifting to harvests and preparing for winter, this is the perfect time to sow flowers that will give you a burst of color next spring. By planting now, you’re giving these hardy blooms the chance to settle in, develop strong roots, and be ready to take off as soon as the first signs of spring arrive.

If you’re like me, and your heart sings at the sight of a vibrant flower bed, here are some of my favorite flowers to sow in September that will transform your garden come next year.

Why Sow in September?

Before we get into the flowers, let’s talk about why September is such a wonderful time to sow. The cooler temperatures make it easier for seeds to germinate, and the soil is still warm from the summer, giving them a great start. Many of the flowers I’m about to mention are hardy annuals, which means they can survive a cold winter and burst into life in the spring.

Sowing in the fall gives them a head start, ensuring they bloom earlier and stronger than if you wait until spring. Plus, isn’t it lovely to know that while the garden may look quiet over winter, there’s something wonderful happening beneath the surface?

My Top Picks for September Sowing

1. Sweet Peas (Lathyrus)

Sweet peas are one of my absolute favorites. They’re romantic, fragrant, and add a dreamy, vintage feel to any garden. By sowing them now, you’ll get earlier blooms next spring, and they’ll grow into stronger plants. Choose a sunny spot with well-drained soil, and don’t forget to give them something to climb on—sweet peas love to reach for the sky.

Tip: Soak the seeds overnight before sowing to speed up germination.

2. Cornflowers (Centaurea cyanus)

Cornflowers, with their charmingly wild look, are a must for any cottage garden lover. They come in shades of blue, pink, and white, and they’re so easy to grow. They thrive when sown in September, establishing themselves through the winter and blooming early in the spring. Scatter the seeds where you want them to grow, and they’ll pretty much take care of themselves.

Tip: Cornflowers attract pollinators, so they’re not just pretty—they’re also great for your vegetable garden.

3. Nigella (Love-in-a-Mist)

Nigella, also known as Love-in-a-Mist, is a whimsical addition to any flower bed. The delicate flowers sit atop feathery foliage, and the seed pods are just as decorative. They’ll self-seed for years to come, giving you a touch of magic each spring.

Tip: Nigella loves sunny spots, so plant them in a bright area for the best results.

4. Calendula (Marigold)

Calendula is such a cheerful flower, and one of the easiest to grow. These sunny blooms are a lovely addition to borders, beds, and even containers. Sowing in September ensures early blooms next spring, and they’re incredibly hardy—surviving frosts and bouncing back with bright flowers. They also have a lovely herbal quality, with petals you can even use in the kitchen!

Tip: Calendula is great for companion planting, especially in your vegetable garden, as it repels pests.

5. Poppies (Papaver rhoeas)

Who can resist the delicate beauty of poppies? These paper-thin petals are iconic, and they’re so rewarding to grow. Autumn is the perfect time to sow poppies—just sprinkle the seeds on top of the soil and let nature take its course. They’ll germinate over winter and explode into bloom in early spring.

Tip: Poppies thrive in poor soil, so you don’t need to worry about giving them too much attention—they’re happiest when left to their own devices.

How to Sow for Success

Sowing these flowers couldn’t be simpler. Here’s a quick guide to make sure you’re giving them the best start:

  1. Prepare the soil: Make sure the area is free of weeds, and rake the soil to a fine texture.
  2. Water gently: After sowing, give them a gentle watering to help the seeds settle in, some of these seeds are tiny, so make sure they don't wash away.
  3. Protect if needed: If you’re concerned about frost or pests, cover the seeds with a thin layer of horticultural fleece for extra protection.

Looking Forward to Spring

There’s something special about knowing that even as the garden starts to quiet down for winter, the seeds you plant now are busy preparing for their grand debut. These hardy flowers will not only bring joy to your spring garden but they will also keep your ground covered in the winter.

So why not give them a try? You’ll be rewarded with early blooms and the satisfaction of knowing that your spring garden was already well on its way during the colder months.

I hope this has inspired you to get outside and start sowing! What is your favorite flower to grow over the winter?