The Best Flower Seeds to Sow in September

What to plant in September: 14 picks to fill your garden with now

What to plant in September will give your garden a lot to look at when it gets cooler. Whether you want to make an immediate impact with pretty bedding plants or sow seeds or plant bulbs for early spring displays, our ideas will make sure you have plenty to enjoy.

If you plant any flowers this month, don’t forget to water them while they get established. This is especially important since September is often a warm, dry Indian summer.

After a summer of growing, the soil may also need to be improved. Add a lot of well-rotted compost or manure to the ground. This will feed your new plants and help it keep its moisture.

Nectaroscordum siculum, also known as Sicilian honey garlic, is a unique allium that gives borders height and style (credit: John Richmond/Alamy Stock Photo).

One of my favorite alliums for garden borders is Nectaroscordum siculum or Sicilian honey garlic.

Most onion relatives have round flower heads that are purple or white. This allium, on the other hand, opens up into umbrella-shaped flowers that are pale cream, pink, and have green tips.

Growing to almost 4ft (1. 2 m) in the best conditions, and they’re still fun to look at after the flowers die off because the tall, straight stems produce arrowhead-shaped seed pods that grow straight up.

The arrowhead seed pods of Nectaroscordum siculum are worth keeping for garden interest ( credit: Future/Ruth Hayes)

Put the bulbs in a sunny spot with well-drained soil that has been improved with compost or farmyard manure. Plant them about two to three times their own depth and a bulb’s width apart, and try to group them in odd numbers so they don’t look too regimented.

Firm the soil around the bulbs just a little and water them well. They should bloom next spring.

Tip: You can also grow Nectaroscordum siculum from seeds, but it will take them about six years to flower.

Red hot pokers

Even though red hot pokers are usually red, people also like yellow and cream varieties (credit: Botany Vision/Alamy Stock Photo).

For a bit of late summer heat, add some red hot pokers to your borders.

These plants, which can handle drought, are also known as kniphofias. They have strap-like leaves and tall spires of glowing red flowers, though you can also find them in yellow and cream.

Though traditionally tall, dwarf varieties look lovely planted towards the front of your beds.

To plant, make a hole that’s as deep as the plant’s root ball but a little wider. Then, fork some well-rotted organic matter into the hole.

Put the plant in water for about 30 minutes to soak the root ball. Then, carefully take it out of the pot and use your thumbs to loosen any roots that are tangled or going around the pot.

First, put the red hot poker in the hole. Then, fill in around the roots with soil and compost, pressing it down to get rid of any air pockets. Water well and mulch the root area with compost or manure to retain moisture.

Tip: If you are planting in clay soil, make the sides of the hole more draining by forking them up. This way, the roots won’t get stuck in a “bucket” of water that can’t get out.

There are many sedums with green leaves and pink flowers, but this “Purple Emperor” variety stands out (credit: Gary K Smith/Alamy Stock Photo).

Sedum, also known as stonecrop, is a beautiful flower that blooms in the fall and provides late-season nectar for bees and butterflies that are looking for food.

They have fleshy leaves that are green and purple and different shades of pink flowers that grow in flat, spreading clumps. They are also called “ice plants.”

They are great for a low-maintenance garden border, like to be in the sun, and are one of the most drought-resistant plants. However, young plants should be protected from slugs and snails. I’ve found that putting a ring of wool pellets like Slug Gone (available on Amazon) around plants keeps pests away and also acts as mulch to keep the soil moist.

You can plant stonecrop at the front of a border or in pots with multipurpose compost that has grit added to help the soil drain better.

If you cut sedum plants in half and remove one stem, you can do the “Chelsea chop.” This will keep them neat and flowering all summer, and in the fall, you can leave the faded flowerheads on.

Iris reticulata are a beautiful way to add low-growing color to borders, rock gardens, and pots (Stock Photo: katewarn s/Alamy)

Iris reticulata are early-blooming spring flowers, grown from bulbs in a sunny spot with rich, free-draining soil.

A dwarf variety, their flowers are traditionally violet with yellow markings. But newer types, like ‘George,’ have beautiful pinky-purple petals, and ‘Natascha,’ has blue petals that are so pale they almost look white.

Irises reticulata, also known as reticulate irises, are native to dry parts of Europe. They look great at the front of borders and in pots. They are also worth considering as plants for rockeries.

Tip: Plant the bulbs in the fall for flowers in the spring, or buy plants that are already flowering in late winter if you don’t want to wait.

Verbascum, also known as mullein, grow in this variety called “Clemantine.” It makes borders taller and looks good in both cottage and modern gardens (credit: Ellen Rooney/Alamy Stock Photo).

Verbascum plants are a great way to add height to a border. They are stately perennial or biennial plants with spires of clustered flowers in shades ranging from deep purple to creamy yellow.

Soil that is neutral to alkaline and drains well is best for them. They look great in cottage gardens, but they will also work well with more modern curb design ideas. Try them with ornamental grasses and bright hardy annuals such as poppies and cornflowers.

Verbascums, which are also called mulleins, do best in partial shade but also like the sun. They are great to add to a wildlife patch because they attract many helpful pollinators.

However, mullein moth caterpillars—yellow, black, and white-striped grubs that can do a lot of damage to your plants—can attack them. The best defence is to pick them off and add them to the bird table.

Top tip: Verbascum flower early in the summer. A second set of flowers should appear later in the summer if you cut back the stems that have flowers on them.

Bedding chrysanthemums bring a shot of low-growing color to borders and containers( credit: Tim Gainey/Alamy Stock Photo)

Chrysanthemums, which are also called “chrysanths” and “mums,” were popular for a while but then lost their appeal and got a bad name for being dull and retro.

People are learning how to grow chrysanthemums more often now that they are trendy again and a top garden trend. Its easy to see why too. They are easy to care for and come in many colors, flower sizes, and heights. They are the dahlia’s less flashy cousin, but they are just as beautiful.

Most chrysanthemums are bought as rooted cuttings or small plants in the spring, but garden centers and online stores will have a lot of beautiful, bright bedding varieties in stock now, so they are an easy thing to add to your September planting list.

These are usually dwarf plants that form clumps of gem-shade flowers in pinks, reds, russets, and oranges. They will flower long into the winter and again next spring.

Top tip: Deadheading flowers regularly will keep the blooms coming and the plants in a neat shape.

Sweet rocket is a beautiful, tall-growing early summer biennial( credit: Future/Ruth Hayes)

If you planted some biennials in the spring and summer, the seedlings should be ready to go to where they will grow.

In the plant world, foxgloves, sweet rocket, wallflowers, and honesty are all biennials, which means they grow one year and flower the next.

This means that many of these plants will happily spread seeds around the parent plant. If you are already growing them, you may find seedlings popping up in places you didn’t want them to.

Plant biennial seedlings, such as this foxglove, where you want them to flower next summer( credit: Future/Ruth Hayes)

Carefully dig them up, making sure to leave some soil around the roots. Then, plant them where you want at the same depth they were growing at before. Keep them well-watered.

Alternatively, pot them up in peat-free compost and overwinter them in a cold frame or unheated greenhouse. Next spring, when the soil warms up, you can plant them out where you want.

Tip: If pink and white honesty has grown on its own, you can leave it alone or throw it away if you don’t want it. These plants have long, thick tap roots and don’t transplant well.

Cyclamen hederifolium flowers add color to the garden in the fall and early winter (Alamy Stock Photo by Jannis Tzimopulos).

Cyclamens are a great choice for what to plant in September because they have bright flowers and leaves with interesting patterns.

They are great plants for shade and seem to shine in the dark. Their corms will grow more over time. They also boost their numbers by self-seeding.

Cyclamen coum and Cyclamen hederifolium are the best types to grow outside. Cyclamen coum has green leaves with white streaks and pretty little flowers in pink, red, and white. Cyclamen hederifolium has pink and white flowers and leaves that look like ivy.

Both varieties thrive in humus-rich soil and are lovely under trees and shrubs.

Cyclamen seedpods are held up by curled stems after they flower. As they ripen, the stems slowly unwind, letting the seeds fall to the ground.

Ornamental cabbages and kales are an unusual addition to flower beds and containers( credit: Ian Evans/Alamy Stock Photo)

You don’t have to laugh at this idea for what to plant in September! Ornamental brassicas are not at all like soggy, over-boiled cabbage or the smell of old laundry.

Many of them have brightly colored leaves that come in different shades of green with mauve, purple, and steely tints. These leaves are a cool contrast to the bright and shiny colors of spring and fall bedding, and their color often gets deeper as the temperature drops.

The best part is that you plant them when cabbage white butterflies aren’t around, so you don’t have to keep an eye out for caterpillars for weeks on end.

When planted in borders, ornamental cabbages look great, but they also look great in pots, baskets, and rockeries where they are contained.

As a bonus, you can eat these pretty plants when they are young, but they don’t taste as good as the brassicas we grow for cooking.

If you want to learn how to grow winter brassicas to eat instead of just for looks, our guide has information on how to grow cabbage, cauliflower, kale, and sprouts.

Dierama pulcherrimum or angels fishing rods have a delicate beauty( credit: Clifford Rhodes/Alamy Stock Photo)

If you can wait, now is a good time to plant the seeds of Dierama pulcherrimum, also known as angels in a fishing rod.

You have to be patient because the plants can take up to five years to flower fully. But when they do, you’ll be rewarded with delicate and beautiful plants with thin, strap-like leaves and gracefully drooping skeins of bells in deep pinks and mauves.

If you already have the plant, get the seeds as soon as they’re ready. Our guide on how to get seeds from flowers shows you how to do this. Spread the seeds out thinly on top of a tray of seed compost when you plant them. Don’t cover them with more compost or vermiculite because they need light to grow.

When the seedlings are big enough, prick them out and let them grow until they are big enough to be planted outside in sunny, well-drained soil.

It looks great for dierama to grow near water among ornamental grasses, but the corms that grow from their seeds when they’re ready to be planted need to be somewhere dry.

Top tip: Dierama will grow in containers, but are much happier in the soil. In winter, mulch corms with well-rotted compost or manure if very cold weather is forecast.

Here are some small violas that you can plant now for spring bedding. They come in many colors and are easy to grow.

Violas are a spring bedding stalwart. They are smaller than pansies, so winter weather is less likely to damage their petals. They will happily hide out during the worst of the storm and come back to life when conditions get better.

You can plant a lot of different kinds of flowers in September. The classic purple and yellow “Johnny Jump Up” is one option, but you can also plant the colorful “Chicky Chicks” and “Pink Halo,” which have pink-mauve petals with darker inky rings and yellow centers that look like faces that have been squashed together.

Plant the seeds in a tray of wet seed compost. Cover with a little more compost and let them grow on a warm, sunny windowsill. Prick out seedlings when they are large enough to handle and pot them on in peat-free compost. There are tips on how to transplant seedlings in our guide.

Harden off plants in spring and plant them out when the weather warms.

Pansy plants often get leaf spot, which you can see on this group of violas (credit: Future/Ruth Hayes).

Top Tip: Violas and pansies can get leaf spot, a fungal disease that makes the leaves look oily and dark and makes the plants weak. To avoid it, plant homegrown plants in garden spots where violas and pansies have never grown before.

What Flowers to Sow in September with Gardening at Douentza | Seeds to Sow Now in Autumn

FAQ

Can flower seeds be planted in September?

Are there any flowers you can plant in September?

Can you sow flower seeds in the fall?

When is the best time to sow flowers in September?

Discover the best flowers to sow in September. the beginning of autumn is the best time to sow some of your favourite spring and summer flowering plants – poppies, lupins, cornflowers, larkspur and lots more, are all best seeded now, ready to grow quickly as soon as the days lengthen and the weather warms.

Can you plant flowers in September?

As a transitional month, September offers just enough warmth for seeds that need to be sown in late summer yet is cool enough for many fall sowings. This article reveals some of the best flowers to plant in September. However, most of the flowers to plant in August can also be planted this month.

Can you plant coneflowers in September?

‘Coneflowers, known for their daisy-like petals and cone-shaped centers, make an excellent choice for the September garden,’ says Reese. ‘They come in various colors, including purple, pink, red, white, yellow, and orange.’ ‘Sow coneflower seeds directly into the soil outdoors in September to kickstart their growth,’ says Reese.

Should you plant flower seeds in fall?

Sowing flower seeds in fall is as easy as it gets. By choosing seeds that naturally self-sow at this time year and need the cold of winter to germinate in spring, also known as vernalization, we’re just imitating what nature does naturally.