At this time of year, just when plants are entering their dormant phase, I always look at the overcrowded clumps of perennials dying down and decide what I need to lift and divide next year.
Dividing plants involves digging them up, splitting them into pieces which each have roots and growth shoots or buds, and then replanting them. The method stops many herbaceous plants becoming overcrowded, untidy and invasive.
Many perennials, including delphiniums, heuchera, hostas, anemones, phlox and cranesbill geraniums, benefit from regular division to maintain their health and vigour, and require no special conditions when new, divided sections are replanted. Other plants benefit from division every three to four years although some, like asters, are best divided annually. A few, including red hot pokers and peonies, hate being moved so only lift and divide them if you want to propagate them.
The best time to divide plants is autumn, when they are dormant, and spring, when they are just starting into growth. Grasses including bamboos should be divided in early spring, while perennials which flower in spring and early summer, such as lily-of-the-valley, epimediums and rhizomatous bearded irises, should be divided as soon as they have finished flowering.
There are various ways to divide plants. Those with tough roots which are difficult to prise apart, such as hostas, are better off being dug up and then cut into thick slices with a knife like you'd a cake, making sure good roots are present in each slice. Other plants can be lifted carefully with a garden fork, working away from the crown centre to limit root damage, then split into two portions across, each with some roots, shoots or buds. Larger pieces with more roots are likely to flowers sooner than small ones, which may take a year to recover. If you are digging up a clump, remove the centre portion, retaining the younger outer parts for replanting. If any sections are short of roots, trim the leaves to reduce moisture loss.
Evergreen and perennial ornamental grasses should be left until spring, when they've had a chance to recover from all the energy they've expended making their feathery plumes in autumn. Young, newly planted grasses also hate sitting in the wet, heavy soil that so often prevails in winter, so don't divide them until spring.
Cut down the foliage of evergreen grasses in spring and divide them, while bamboo stems can be cut down to 30cm (12in). Perennials such as daylilies (hemerocallis) have masses of fibrous roots and large crowns which are difficult to pull apart, so use two forks thrust back-to-back in the centre and work the handles outwards in opposite directions to loosen the clump. You may then have to use hand forks to divide it completely, or cut away sections with a sharp knife.
Plants with fleshy roots, such as delphiniums should be cut with a spade or knife. Divided clumps should ideally contain around three to five shoots.
Divide primulas into rosettes, asters into single rooted shoots and bugles into single rooted plantlets. Clumps of epimediums should be teased apart into separate plants using your hands or a hand fork, replanting on mild autumn days, while crocosmia and crocus clumps can be dug up and the new corms which are resting on the original ones can be eased off and replanted up to 10cm deep.
When replanting, add compost or well-rotted manure to the planting hole on a new site, or a balanced fertiliser if you are replanting the divisions into the same hole. They should be replanted at the same depth in flowering positions and watered in well.
Alternatively, pot up divisions while you decide where you want your new plants to grow, overwintering them in a cold frame.
Before long, you'll have an array of new plants - which won't have cost you a penny.
Best of the bunch - Actaea (Bugbane)
Good enough to eat - Pumpkins
They are grown in the same way as squash. Seeds should be sown individually in 9cm pots of multi-purpose compost, indoors, in late spring, pushing each seed to a depth of 2cm. Water thoroughly then grow on until the first two leaves are well developed and then harden them off before planting.
Pumpkins are frost-tender so don't plant them out until danger of frost has passed. They need plenty of space and an open sunny position in a moist, fertile soil rich in organic matter which has been added in autumn and winter.
After planting, surround each plant with a low rim of soil, about 30cm (12in) out from the stem and fill the basin with water when the plant needs moisture. Then water regularly during the summer and keep the area well weeded, adding a liquid feed regularly. Before long, the huge foliage will act as ground cover to smother the weeds. By the end of summer you should reduce feeding and watering and remove any foliage blocking sun from the fruits, which will need to ripen. Pick them when ripe and certainly before the first frosts.
Good varieties include 'Becky', ideal for Halloween, and 'Summer Ball', which is good for growing in containers.
Top buy - Wheelbarrow Booster
What to do this week
Cut out loganberry and blackberry cans that have finished cropping, and tie in new ones to the support framework.
Protect cauliflower curds by bending two or three leaves over them.
Start heating the greenhouse at night to protect tender plants if frost is threatened.
Make new lawns from turf.
Examine pears in store every few days, and eat them as soon as they are ripe.
Shelter pot-grown strawberries from heavy rain.
Cut down the top growth of dahlias when it is blackened by frost, then lift and dry the tubers for storage.
Remove half-hardy fuchsias from the garden and from containers, and put them in pots to overwinter under cover.
Wrap containers of potted acers with horticultural fleece to stop the compost freezing and protect the plant.
Continue to clear fallen leaves, and recycle them to make leafmould.
Take hardwood cuttings of roses and root outdoors.
Cut down faded border perennials and lightly fork the soil between them.
Dig up and store gladiolus corms.
Finish lifting potatoes, leaving them on the surface of the soil for a couple of hours to dry out, or in a greenhouse if it's damp. They must be dry before putting them into storage.