September Garden & Greenhouse Checklist

A practical guide to what to sow, plant, prune, and prepare this month

Flowers & Borders

• Sow hardy annuals like cornflowers, cerinthe, ammi, and scabiosa for early summer blooms.

• Lift gladioli corms, dry them, and store frost-free.

• Plant spring bedding: wallflowers, pansies, forget-me-nots.

• Collect seeds from favourite flowers and store for spring sowing.

• Fill pots for autumn colour with cyclamen, heathers, heucheras, and other seasonal bedding.

• Divide and replant perennials like achillea once flowering finishes.

• Control vine weevils if you spot notched leaves on potted plants.

• Add late-flowering perennials like sedums to support pollinators.

• Plant spring bulbs: crocus, daffodils, hyacinths, bluebells, fritillaries.

• Take cuttings from fuchsias, salvias, pelargoniums.

• Keep summer bedding going with regular deadheading and feeding.

• Trim conifer hedges to tidy and manage height.

• Leave sunflower heads for birds to feed on.

• Make an autumn wreath with garden foliage and berries.

• Visit other gardens for late-season inspiration.

Fruit & Veg

• Sow hardy greens: kale, pak choi, mustard, mizuna, land cress, lamb’s lettuce.

• Prune summer raspberries: remove fruited canes, tie in new growth.

• Pot up herbs like parsley and chives for indoor use.

• Sow broad beans and peas for early crops next year.

• Plant onion and shallot sets with tips just above soil.

• Expose pumpkins and squash to sun by removing shading leaves.

• Plant saffron crocus bulbs for an autumn harvest.

• Pick apples and pears before wind damage; store undamaged fruit.

• Dry chillies by threading and hanging in a warm, dry spot.

• Ripen green tomatoes indoors before cold weather hits.

• Lift and store potatoes in cool, dark, ventilated sacks.

• Finish summer pruning of apple and pear trees.

Garden Maintenance

• Rake and spike lawns, re-seed bare patches.

• Net ponds to catch falling leaves and reduce rot.

• Water autumn asters to prevent mildew.

• Clean water butts and check fittings before heavy rain.

• Clear pondweed and algae from water features.

• Secure tree ties and supports ahead of autumn winds.

• Disinfect bird feeders and tables to prevent disease.

• Collect fallen leaves to make leaf mould.

• Check rosemary and lavender for beetles and larvae.

• Remove rotting fruit to prevent fungal spread.

• Order bare-root fruit trees for winter planting.

• Inspect roses for blackspot and remove affected leaves.

Greenhouse Tasks

• Plant hyacinths in pots or glasses for Christmas blooms.

• Remove shading by end of month to boost light.

• Watch for pests and diseases, treat promptly.

• Plant dwarf bulbs: irises, crocus, scilla, chionodoxa.

• Pot up tender perennials like fuchsias and osteospermum before frost.

• Plant Anemone De Caen for spring colour indoors.

• Ventilate carefully, closing vents on cool nights.

• Check heaters and plan for winter warmth.

• Keep greenhouse tidy, removing dead leaves and blooms.

• Prepare for early frosts, move tender plants inside.

• Relocate peaches and nectarines to sheltered spots.

References

BBC Gardeners World Magazine. (2024). What to do now – September. [online] Available at: https://www.gardenersworld.com/what-to-do-now-september/ [Accessed 21 Sep. 2025].