September gardening tips
Bulbs, flowers and containers
September is the prime time for planting spring bulbs; choose plump firm bulbs and plant within a week of buying in a location with good drainage. Add a little bonemeal for a slow-release fertiliser and grit if the soil is heavy. Ensure pots and containers have plenty of crocks at the bottom. Bury bulbs at twice the depth of their size, tip upwards and ensure there are no air pockets around them. Use them to fill gaps in beds and borders, in formal gardens, in pots and containers, under shrubs and trees or naturalised in grass or woodland.
Make your life easier by investing in a strong good quality dibber and if you have a bad back, a long handled bulb planter.
Start with narcissi, alliums, crocuses, scillas and chionodoxas - tulips should be left until November.
For a natural look, throw handfuls of bulbs in the air and plant them where they land.
The last chance to plant indoor bulbs to be in flower (hopefully!) for Christmas is mid September. Use bulb fibre or multi-purpose compost with a little added grit, set the bulbs as close as they can possibly be in a bowl at least 4" deep, preferably with a drainage hole. Narcissi and hyacinths should have their noses just showing - all other bulbs (crocuses, scillas and tulips are good candidates) must be covered completely. Make sure the compost is well below the rim of the bowl and leave in a cool dark place inside. Don't let the compost dry out and when the leaves are 1 - 2" high move into a cool room; when flower buds appear move into full light – preferably again in a coolish room…Good luck!
Plant new perennials and bring tender ones into shelter. While the soil is moist and warm, plant hardy perennials so their roots have a chance to become established before winter. Water well before and after planting and ensure you choose plants that are appropriate for your soil type! Lift and bring tender perennials inside before frosts cause any damage.
Deadhead dahlias, chrysanthemums, asters and any other spent flowers to keep the garden looking tidy and to encourage dahlias to reflower.
Support and divide! Autumn can be windy so make sure tall flowers are supported. Once perennials have finished flowering, cut them back and divide large clumps by lifting carefully and separating down the centre with 2 forks back to back. Replant with plenty of organic matter and water generously. Remember some perennials, such as peonies, loathe being disturbed so check before you dig them up.
Collect seed heads from perennials, alpines, trees and shrubs. Growing plants from seeds you have collected is fantastically rewarding, but be vigilant; seed heads have a nasty habit of ripening and popping whilst your back is turned. Collect when nearly ripe - just as they are turning brown. Snip them off, put them in a paper bag, label and hang somewhere cool, dark and dry.
If your alpines have outgrown their present home, move to their new location now with a generous ball of soil around the roots and water well once in situ.
Pots and containers
Plant winter bedding and spring bulbs in your pots and containers now. Stop feeding permanent plants and move any tender plants under cover before the cold sets in.
Spring flowering bedding
Buy and plant out violas, wallflowers and primulas now for cheery colour come springtime. Clear old summer bedding, incorporate some organic matter into the soil and plant in drifts for stunning effect. Remember not to grow wallflowers and ornamental cabbages in the same spot two year running; they are brassicas and need rotation to avoid the root disease 'clubfoot', which is not only infectious, but persists in the soil.