September in the garden

The cutting garden

Sowing & growing

• Plant out and transplant biennials.
• Divide and replant perennials to ease any congested areas. Later in the month bring tender perennials, such as pelargoniums, inside to protect from the frosts.
• Continue sowing hardy annuals for early flowering next year – you'll get bigger, better plants which can flower a good six weeks earlier than those spring sown. For example, briza, bupleurum, calendula, centaurea, Papaver rhoeas, Papaver somniferum, and scabious can all be direct sown now. Remember to keep them weed free as they germinate. 
• Clear your annuals as they go over and add them to the compost heap. 
• Sow a pack of Viola 'Heartsease' to flower in about eight weeks' time, right through winter.
• Hunt for self-sown seedlings of hardy annuals and biennials, such as English marigolds (Calendula), honeywort (Cerinthe) and honesty (Lunaria), where you’ve had them earlier this year. If they are overcrowded where they’ve sprung up, transplant them, spacing them 12in (30cm) apart. Or create a line in a cutting patch to harvest flowers next year.
• It's urgent to get wallflowers in place now. These spring-flowering biennials need to get their roots down well before flowering.
• Sow yellow rattle. This is key to the success of any wild flower patch as it reduces the vigour of certain grasses. We devised a good system at Perch Hill, creating circles of almost bare soil with a swish of a strimmer, then scattering seeds direct into these.

Bulbs & tubers

• Now is a good time to start planting your spring bulbs – the ground will still be nice and warm from the summer months, and it gives plenty of time for the new roots to bed in before the spring sunshine arrives.
• Inside, have a go at forcing some hyacinths or amaryllis now for colour over the festive season.
• Plant pots of smaller bulbs such as muscari, iris, crocus, chionodoxa, scilla and anemones. Keep watered during the winter if we have any dry spells (but lift off the ground to prevent waterlogging which is just as bad) to provide pots full of colour for the spring.
• Plant a layered pot of bulbs, known as a “bulb lasagne”, for your doorstep, with the largest and latest flowering bulbs at the lowest level (with at least 6in of soil/compost below the bottom of the bulb) and early flowering, smaller bulbs on top. Excellent combinations are crocus above early tulips (e.g. single varieties such as ‘Prinses Irene’ and ‘Couleur Cardinal’), or try an early grape hyacinth (Muscari azurea) on top, with a late tulip (‘White Triumphator’) below. Top-dress with grit to keep the pot looking good through winter. Watch Sarah make a bulb lasagne in our video guide.
• Plant small bulbs in to your lawn. Think of jazzing up an area of lawn or rough grass with crocuses such as C. tommasinianus, C. vernus and C. chrysanthus hybrids. All are happy in thick turf with the sun fully on them.

Harvesting

Lovely things to pick and arrange from your garden in September:

• Bulbs: gladioli and acidanthera
• Hardy annuals: Euphorbia oblongata, sunflowers and scabious
• Half-hardy annuals and dahlias: all
• Perennials: Euphorbia ceratocarpa, salvias, heleniums, phlox, echinacea, rudbeckias
• Shrubs and trees: hydrangeas, Viburnum opulus, berries and leaves.

Pick a large bunch of late-flowering phlox, such as the pure white ‘Mount Fuji’. It thrives in sun and shade. Strip just the bottom leaves and pile tall stems into a simple jug. Add a teaspoon of bleach or slosh of vinegar to keep bacteria at bay. They will last more than a week.

Pick hydrangeas before they are damaged by wind and rain. To make them last as long as possible indoors, float the flowers overnight in a bath of cool water. Then arrange them in a vase with only an inch or two of water. As this evaporates, the flower heads will dry and keep their colour. If you want them to retain their texture but not their colour, add a drop of glycerine to the water too.

Pick a last bunch of roses before they brown. Sear the stem ends in boiling water before you arrange them to make them last as long as possible.

The kitchen garden

Vegetables

• When you think you’ve harvested your last potatoes, carefully dig over the veg bed, collect those that were still lurking under the surface, and then dig over ready to plant some green manures. These green manures are useful in many ways; they protect the soil from erosion over winter, reducing the potential of any leaching of mineral and nutrients, and also protect soil structure, as well as boosting nutrients when dug into the soil. They also provide a green carpet that helps provide shelter for beneficial insects through the winter, such as ground beetle, and if you leave a patch to flower they are loved by pollinators – Phacelia tanacetifolia for example, is one of the best nectar sources for the honeybee, bumble bee and hoverfly.
• Bean and pea plants that have finished their harvest can be cut back, leaving the roots to be dug in to the soil to provide extra nitrogen for future crops.
• Continue to feed tomato plants until all the fruits have finished growing and ripening. If your tomatoes refuse to ripen in miserable weather, then you could make a delicious green tomato chutney.
• Sow spring onions – these will be ready to eat before the frosts get going in most parts of the country. Even if frosts are forecast, they are fine under glass or plastic to harvest through late winter and autumn.
• Remove any crops that have finished leaving unneeded areas clear – weeding and tidying for the winter. Keep an eye on your brassicas for butterfly eggs and caterpillars; these will most probably be under the leaves.
• Sow Swiss chard, winter spinach, broad beans and hardy peas.
• Keep watering winter squash and pumpkins if the weather is hot. This will prevent their growth from being checked. Use stored rainwater wherever possible. Keep pinching out the tips of triffid-like pumpkins and squash. They prioritise vegetative growth over fruit formation, and you may get fruit drop if you don't keep them contained. With the tips pinched, all the fruit down to the base of the stem will now be ripening well. Place a tile under the largest fruit to stop rot creeping in where they sit on the damp soil. Leave pumpkins, squash and marrows to ripen in the sun as long as possible so that the skin can harden.
• Prepare a bed for autumn-planted shallots. Incorporate well-rotted compost into the area to improve fertility. If your ground is wet, a raised bed may be a better option. Plant the sets from the end of the month, with the tip just protruding from the soil.
• Do a last outside sowing of radish. With the soil still warm and moist with dew, you should be eating these in four to five weeks.

Salad & herbs

• Direct sow a row of rocket. It seems late to still be sowing seed, but salad rocket does not bat an eyelid at the cold or wet. There’s no flea beetle around now either and the scourge of the slug and snail is on the decrease. Don’t just scatter the seeds willy-nilly, but space them a couple of inches apart, to make thinning (or transplanting excess seedlings to a second row) easy.
• Sow all your autumn-winter picking salad leaves and herbs if not done in August.
• Cut and hang herbs to dry for using in the kitchen over winter.
• Sow coriander now and you may be harvesting until April or May next year. Sow in a row outside, or into a gutterpipe for planting out in a month’s time.
• Long-season herbs, such as chives, lovage and sorrel, should all be cut to the ground. They will be up again in a couple of weeks with fresh leaves. Drench with slow-release, potash-rich liquid comfrey fertiliser to encourage strong regrowth.
• If weather is dry, water well. Pot up less hardy herbs such as parsley, chives and French tarragon and bring inside into a sunny, frost free spot.

Fruit

• Once harvested, it's time to start thinking about pruning back your fruit trees and shrubs to maximise yields next year. As a general rule of thumb the sooner this is done after harvesting the better.
• Pot up strawberry runners to make new plants for next summer.
• Cut back the fruited canes of summer raspberries, tying in the new green canes for next year’s crop.
• If you are not sure when your apples are ripe, gently lift them in the palm of your hand or give them a gentle pull – they should come away easily from the branch without needing to be pulled hard.

Harvesting

Here's what you could be picking and eating this time next year or, if you're an old hand, already are:

• Brassicas: kohl rabi and kale
• Roots: radishes, carrots, maincrop potatoes, stored onions, beetroot
• Salad crops: salad leaves, pea tips, all lettuce and Florence fennel
• Edible flowers: nasturtiums, runner bean and courgette flowers
• Leafy greens: chard and spinach
• Legumes: peas, Borlotti, French and runner beans
• Squash: courgettes, Red Kuri squash and Pumpkin ‘Munchkin’
• Fruity veg: tomatoes, cucumbers, aubergines, peppers and chillies
• Other veg: globe artichokes and sweetcorn.
• Herbs: all
• Fruit: autumn raspberries, plums, damsons, first cobnuts and walnuts, apples and first quince and pears.

Pick figs as and when they ripen, bottling them in vodka if you can’t eat them all fresh. They can be sliced to serve as a delicious topping for vanilla ice cream, and you can drink the spirit as you would sloe gin.

Pick gluts of damsons, plums and apples to make jams, flavoured gins and chutneys in preparation for the coming winter. Store in good airtight bottles and jars and they’ll last for months.

Harvest all your sweetcorn, blanch and freeze. Strip the husk and blanch the cobs in boiling water for four to six minutes, depending on size, and then cool immediately in cold water. You can store these in the fridge for up to five days, or freeze them.