How to get the best out of agapanthus all year round When I was a teenager, perceived wisdom meant that many gardeners dallied with the Agapanthus Headbourne Hybrids, which are deciduous/semi-evergreen, and are supposedly hardier than the wider, more strappy-leaved, solely evergreen varieties, but have smaller, less punchy flowers. Now with climate change, better composts and more adventurous gardeners, many people grow the evergreen and supposedly more tender varieties outside from north to south, leaving them in borders over winter with fantastic results. That includes the last two freezing winters. Steve Hickman runs the Hoyland Plant Centre in South Yorkshire (somethingforthe garden.co.uk) and grows only agapanthus and tulbaghias, having a National Collection of both. He believes his A. Headbourne hybrids are true to type. He propagates by tissue culture (micropropagation) or division. He sells clumps of rhizomes from mid-September to April (if you collect) or sends out 9cm (3½in) and two-litre pots all year round. He reckons that although they are easy to grow, if you follow four simple rules they will exceed your expectations rather than disappoint. Most critically, make sure they have good drainage. In pots he uses two parts of compost to one part of coarse sand or gravel. Where they grow naturally in South Africa, on cliff tops, crevices and ledges, there is precious little soil. Restricting them makes the plants flower sooner, but when they mature over several years in the open ground, they get to their full size. In containers, even when they are fully mature they will not get to their ultimate size because of the bonsai effect, unless it's a very large container or a dwarf agapanthus. This is why plants directly planted in the border can take years to flower reliably, but when they do their flowers are more spectacular. Thirdly, feeding is key. High potash feeds, such as the one Hoyland sells for agapanthus (which is 30 per cent potash and trace elements), applied every three or four weeks in the growing season, with a general feed twice or so in the summer, will keep the flowers coming. The fourth factor is overwintering. Those evergreen types in containers can have a last watering in early November and about a fortnight later the containers and plants should be wrapped in fleece and put in a polytunnel or greenhouse - if not available, a shed with some light is fine. Deciduous types can cope with a dark shed. They can be unwrapped around the end of March. For those in the ground (evergreen and deciduous), a foot or so of bark mounded over the plants, letting it settle around the leaves (lift them as you apply it) insulates the rhizomes from severe temperatures. The exposed leaves will go mushy but the plant will survive. I was amazed at the drifts of tall, stunning agapanthus at Harlow Carr - even that far north after the 2011 winter. They are tougher and more vigorous in a border than I had realised. There are lots to choose from. I read a press release of a newish Agapanthus 'Blue Storm" (and 'Whitestorm") which claimed that it flowers for 70 days (two to three weeks longer than usual) with a mature plant (four years old) producing up to a hundred stems of 100mm (4in) diameter blooms. At just over 75cm (30in) high, it is fairly compact. It is an evergreen variety and according to Anthony Tesselaar, who bred it in Australia, most agapanthus produce flowers just once a year, but 'Blue Storm" produces subsequent light flushes in autumn and sometimes even in winter. Which? magazine did a trial of 19 varieties (before 'Blue Storm" was released) and A. 'Northern Star," A. inapertus 'Midnight Cascade" (a deep indigo) and Double Diamond (white) came up trumps. Steve Hickman has bred a few and 'Margaret" and 'Hoyland Blue" are two of his favourites. The other rhizomatous bulb from South Africa that is a new best friend is Tulbaghia violacea. I am planting a mass of them this weekend, sprinkled throughout a border full of topiary. They flower from April to November with their beautiful umbels (about 3-4in across) of lilac-pink flowers that stand about 50cm (20in) high above linear glaucous green foliage. They are not unlike the better-known purple alliums, but have better staying power and are more delicate looking. The foliage is a big asset, too. They are hardy outside in Edinburgh Botanic Garden (generally they tolerate down to around -9C/15F) and favour a sunny position. They benefit from dividing every two to three years and apart from cutting back the old foliage in November, you need do little else. They work well in a pot and the variegated form, T. v. 'Silver Lace," has charming foliage too, and I know gardeners who dislike variegated plants that rave about it. This is less hardy though - I will bring mine in.