What to sow and grow in September

What-vegetables-to-plant-September-flowers-sow-grow-hero - Kniphofia 'Erecta' from Thompson & Morgan
Sow 'Red Hot Pokers' for stunning displays next summer
Image: Kniphofia 'Erecta' from Thompson & Morgan

September might be peak harvest time, but there’s still plenty to sow and grow this month.

Here's a handy list of what to plant in September, along with the flowers, fruits and vegetables you can grow this month:

Flowers to sow and grow

What-to-plant-September-flowers-sow-grow-verbascum - Verbascum x hybrida 'Snow Maiden' from Thompson & Morgan
Start verbascum off in a cold frame
Image: Verbascum x hybrida 'Snow Maiden' from Thompson & Morgan

Here are the flowers to sow and grow this month:

In the greenhouse/indoors

  • Surface-sow euphorbia seeds now in trays indoors.

  • Sow dierama seed now on the surface of moist compost. Keep in a cool greenhouse over winter.

In the cold frame / under cloches

  • Sow calendula seeds in pots now and keep in a cold frame, for fruity colour from early summer next year.

  • Sow violas in a cold frame to plant out in the spring.

  • Sow lupins, aquilegia, aconitum and hollyhocks in a cold frame now.

  • Sow eryngium and echinops in pots and place in a cold frame this month to enjoy their silvery spiky foliage next year.

  • Start verbascum seeds off outdoors now in pots in a cold frame.

  • Sow perennial salvias into pots and trays outdoors and leave in a cold frame or unheated greenhouse through the winter.

  • Sow red hot pokers into pots and trays outdoors for stunning flowers next summer.

  • Sow helenium in a cold frame to attract bees and butterflies into your garden next year.

Direct sow outdoors

  • Sow Ammi majus (Bishop's Weed) directly in the ground now where you'd like it to flower. Autumn sowing will produce bigger, more robust plants to grow.

  • Sow hardy geraniums outdoors and leave them to over-winter.

  • Direct sow hardy annuals, such as cornflowers, poached egg plant, annual poppies and larkspur, for bigger plants next year.

  • Sprinkle California poppies into your borders for stunning colour late next spring.

  • Direct sow Love-in-a-Mist (nigella) - it will over-winter quite happily and will self-seed prolifically!

  • Sow delphiniums this month for flowers next summer.

Plant outdoors

What-to-plant-September-flowers-sow-grow-chrysanthemums - Chrysanthemum x hortorum 'Anastasia' from Thompson & Morgan
Extend the season by filling any gaps with chrysanthemums
Image: Chrysanthemum x hortorum 'Anastasia' from Thompson & Morgan
  • Fill gaps in your borders with autumn-flowering plants, such as sedum and chrysanthemum, to extend the colour to the end of the season.

  • Plant hyacinth and amaryllis bulbs for forcing, to ensure a crowd of colourful blooms at Christmas. Keep them in a dark, cool place like a shed or garage and bring them indoors when the shoots are 5cm tall. Perfect for a homemade Christmas present!

  • Plant spring-flowering bulbs, such as daffodils, crocus and hyacinths.

  • Plant out any biennial plants sown earlier in the year. This includes foxgloves, wallflowers and violas.

  • Plant new perennials, trees and shrubs. Now is a good time as the soil is still warm and increasing rainfall should be on its way.

Vegetables and herbs to sow and grow

What-to-plant-September-vegetables-grow-radish - Radish ‘French Breakfast’ from Thompson & Morgan
September's your last chance to sow summer radishes
Image: Radish 'French Breakfast' from Thompson & Morgan

Here are your vegetables and herbs to sow and grow this September:

In the cold frame/ greenhouse/ under cloches

  • Direct sow spinach now and offer cloche protection as the weather cools. This will ensure harvests throughout autumn and winter.

  • Sow spring cabbages, such as 'April' and 'Durham Early' into modules in the greenhouse.

  • Sow pak choi under cloches now for an autumn supply of baby salad leaves.

Direct sow outdoors

  • Sow corn salad (lamb's lettuce) now - it’s a fully hardy crop which can be sown outdoors now for cropping throughout the autumn and winter.

  • Sow 'green manures' on empty beds now to help improve your soil structure and prevent weeds establishing over winter.

  • Sow 'Hi Keeper' onions into a well-prepared seedbed - these are the best variety of onion for autumn sowing. Only thin your onion seedlings in the spring.

  • Direct sow salad leaves now.

  • Try sowing the very hardy 'Perpetual' spinach outdoors this month for winter harvests later in the year.

  • Sow winter-hardy spring onions, such as 'White Lisbon' and 'Performer' for crops next spring.

  • Make your last direct sowings of summer radishes this month - the cool autumn conditions are ideal.

  • Sow turnip seeds into well-prepared beds this September, for small roots.

  • Sow winter lettuce, such as 'Arctic King', directly into the ground now.

Plant outdoors

What-vegetables-to-plant-September-onions - Onion ‘Shakespeare’ (Autumn Planting) from Thompson & Morgan
It's time to get onion sets in the ground
Image: Onion 'Shakespeare' (Autumn Planting) from Thompson & Morgan

Keep one step ahead - what to order this month

What-vegetables-grow-September-rhubarb - Rhubarb ‘Delight’ (Spring/Autumn Planting) from Thompson & Morgan
Stock up on rhubarb now
Image: Rhubarb 'Delight' (Spring/Autumn Planting) from Thompson & Morgan

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