What to do
If you have just planted a young fruiting cherry, you should shorten the leading branches by half and continue to do this for the next four years. As the trees mature, you have to leave them pretty much to their own devices, taking out only wood that has died or whole branches that are crossing.
Elders grown for their decorative foliage also need regular pruning. If you cut all the stems to ground level, you get the best leaves, but sacrifice the flowers. Cut a third of the stems down to the ground each year instead. That way you can have both.
The snowberry, Symphoricarpos albus, gets overgrown and overtwigged as it ages. Thin it out cutting the twigs down at ground level.
Lilac does not get so congested, but also benefits from regular thinning out of growths. Take out any weak or crossing branches. If you want to rejuvenate an old, overgrown bush, cut the whole thing down to within two feet of the ground. You will not have any flowers for the next couple of years, but the gain is worth the sacrifice.
Continue to plant tulips. They are excellent in tubs and windowboxes, especially the shorter varieties and those with decoratively striped leaves such as the Greigii and Kaufmanniana types. 'Daylight' is brilliant red with a yellow striped base and only 15cm high. 'The First' flowers in March with white blooms tinted on the backs of the petals with deep pink. Miniature tulips, species such as T. tarda or T. whittallii are also charming in troughs and rockeries.
Continue to plant hyacinths in bowls to flower in January and February. Leave dahlias and begonias in the ground as long as possible before lifting. The tubers do most of their growing in the short days of autumn. Lift them only when the foliage has been blackened by frost.
What to buy
The urban ecologist Dusty Gedge has put his considerable expertise in installing green roofs into a practical guide for beginners. For £11.65 you can download it from grassroofcompany.co.uk or livingroofs.org. If you prefer your information on the page, get hold of Planting Green Roofs and Living Walls by Nigel Dunnett and Noel Kingsbury (Timber Press £25).