Take control of shrubby invaders and breathe new life into your garden

The spring catalogues sent out by the bulb merchants are a rum concoction. Anything goes, from dahlias to michaelmas daisies. Some items read like a hangover from autumn. Allium albopilosum (correctly A. cristophii) has its portrait among the liliums in de Jager's catalogue, but does not feature in the alphabetical listings. Still, if you really can get it now, having forgotten to in the autumn, seize the opportunity.

When the legendary Christopher Lloyd died last year, he left behind the manuscript for his final book, which is published this month. In this exclusive extract, he writes about a plant with which he became indelibly associated: the dahlia

Christopher Lloyd delighted Guardian readers with his gardening wisdom for more than 10 years. Today, as friends gather to remember him on what would have been his 85th birthday, we collect some of his best writing.

Christopher Lloyd: In writing about pears, I am torn between the fruit and the tree. An old pear tree, whether or not it fruits, is venerable and achieves a great age, with thick stems and rough, scaly bark.

Christopher Lloyd: I am associated with bright, harsh colours because I do not mind using them when the situation suggests they are needed. But I have no special preference for their brightness per se.

Christopher Lloyd: I love coniferous trees. Even if your garden hasn't room for one, keep your eyes open for those in other people's gardens.

Christopher Lloyd: These are easy garden plants, which will often self-sow. Their colour range is terrific.

Christopher Lloyd: You might think this is an odd time to be thinking about, let alone actually performing, the act of splitting perennials. But it isn't.

Christopher Lloyd: The most stalwart of all winter-flowering shrubs must be the Chinese witch hazels, Hamamelis mollis.

Christopher Lloyd: Does a garden die with its owner? It's a question that is often asked.

Christopher Lloyd: The staple diet between autumn and spring is the genus Mahonia.

Christopher Lloyd: Winter occupies a large section of the year, so we want to be ready for it with our plantings. The sun is low, but it is still there and we need to place those shrubs with interesting stems so that they catch the winter sunlight.

Christopher Lloyd: When the garden is tucked up and ready for winter, there are still some plants that, given the chance, will go on flowering well into winter.

Christopher Lloyd: When putting plants together, what are your thoughts?

Christopher Lloyd: Melianthus major is high on my list of favourite plants.

Christopher Lloyd: Begonia is an amazing genus. There are well over 1,000 species and, between the tropics of Capricorn and Cancer, they extend right round the world.

Christopher Lloyd: There are various schools of thought about whether we should cut down the perennials in our borders at the end of the season.