The best seeds to sow in August

Summer is slowly coming to an end, but this does not mean boredom in the garden. Flower beds are still bursting with colour, joined by more species that are producing flowers.

Plenty of sunshine and warm, late summer temperatures make August also the ideal month for sowing certain seeds and planting out. Here are some tips on what to grow and how – for bountiful crops this winter and into next spring.

Remember to water your beds more often to ensure seedlings and young plants don’t dry out during hot, dry weather.

Seeds to sow

Plants blooming in August

1. Seeds to sow

Spinach

Easy to grow and hardy against frost and rain. Sow seed in August for a first crop in October. Spinach then goes dormant over winter, ready to provide fresh ‘cut-and-come again’ baby leaves in early spring.

Sprinkle seeds thinly into shallow drills, approximately 1.5cm deep and 40cm apart, in well-prepared, fertile soil in a sunny spot.
Cover seeds with soil, and water well. And if the weather is still cool, protect with cloches.
Sow a batch every three to four weeks for a continuous crop.

Rocket

You can’t beat the peppery tang of rocket for spicing up salads. Sow wild rocket seeds in early August for a continuous crop up to winter's arrival, with new growth in March and April.

Mark out a row in the soil with a 1-2m long line.
Sow a small number of seeds, spaced about 3cm apart, every two weeks.
Cover seeds lightly with soil, removing any weeds or large stones as you go.
Drench the soil without moving the seeds too much, using a watering can with a rose head attachment.

Top tip: To prevent flea beetles nibbling holes in rocket leaves, cover the row with a mini tunnel or length of horticultural fleece.

Cabbage

Ideal for making coleslaw, stir-fries and soups. With lots of varieties to choose from, you could be harvesting cabbage in around 20 weeks, almost all year round. Sow spring cabbages in late summer, and plant out winter cabbages grown from seed in previous months now.

For best results, sow seeds indoors in pots or trays, 2cm deep.
About five weeks later, plant the young cabbages outdoors in a sunny spot, after digging plenty of garden compost into firm, moist, alkaline soil.
Space out the cabbages depending on the type, such as 25cm apart for spring cabbages and 45cm for winter varieties.
Suspend fine netting 1m off the ground to stop pigeons and cabbage white caterpillars from eating the leaves.
Use a nitrogen-rich liquid food every fortnight.

Forget-me-nots

Add a springtime splash of pale blue. Forget-me-not flowers are great for filling in shady spots beneath trees and shrubs, the front of borders and path edges. They also add a natural-looking touch among tulips, wallflowers and hostas.

Sprinkle seeds in trays filled with compost. A heated propagator or a warm windowsill will encourage germination.
Prick out seedlings and pot on. Flowers will appear the following year.
It self-seeds easily, so either let forget-me-nots spread naturally, or lift and replant where you want them.

2. Plants blooming in August

Flowers

Plants that began their flowering in June or July still delight with their developed flowers in August. These include, for example, carnations, zinnias and coneflowers, as well as popular bulbous perennials such as dahlias, gladiolas and lilies. But that's not all - although this month marks the end of the flowering season for many plants, there are still some species that are just beginning.

Blue leadwood (Ceratostigma plumbaginoides) - in autumn, its leaves turn a striking reddish-brown, which contrasts nicely with the intense blue flowers.
Garden chrysanthemum (Latin: Dendranthema ×hortorum) - a showy perennial that flowers in August and can decorate a garden or balcony. It comes in hundreds of varieties in yellow, red, pink or white.
Some asters, such as the dwarf (Aster dumosus) or narrow-leaved (A. sedifolius), have flowers with characteristic yellow centres and pink or white petals.
Sneezeweeds (Latin: Helenium) - these frost-tolerant plants produce interesting-looking flowers in various shades of yellow, orange and red.

In addition, it is worth mentioning one of the bulbous perennials that flower in August: Colchicum. Its flowers are usually purple, although there are also yellow and white varieties.

Shrubs and trees

One of the more popular species associated with autumn is undoubtedly heather. Some of them start flowering in August, such as the common heather (Latin: Calluna vulgaris). It is a small shrub with needle-like leaves and distinctive purple flowers, that blooms until early autumn.

In addition, the garden can be decorated with Caryopteris (Latin: Caryopteris ×clandonensis). This blue-flowering shrub is distinguished by its flowers with very long stamens. Its intense colour and pleasant fragrance attracts bees and butterflies. Hydrangeas, roses, summer lilac or lavender also continue the flowering season.

The double-flowering variety of magnolia flowers in August and as standard in spring, so we can enjoy its beauty twice a year. The variety is called Magnolia Soulangeana and Magnolia Grandiflora and, although it takes a little effort to grow, the appearance is worth the effort.