How to propagate agapanthus. Every four or five years agapanthus grown in the garden or in pots should be divided. Lift the plants and carefully divide the crown, making sure that each section has at least two growing points. You may need to use two garden forks back to back to divide very established clumps. How to Grow Agapanthus - BBC Gardeners' World Magazine Please note: You are currently browsing img stunning agapanthus plants for your garden wearefound that is 700x525px in size. This image is listed in agapanthus garden ideas category. How to Grow Agapanthus BBC Gardeners World Magazine, 700x525 in 132.32 KB.