No matter how perfect your rock garden may look today, you will be involved in some replanting in the future and the introduction of new plants will become a fairly regular routine. There are several reasons for this. An obvious one is that there may be an empty planting pocket or area equally obvious is the failure of a plant which needs to be thrown away or be moved to a spot which may offer a better home. Less obvious is the limited decorative life span of many alpines, the average is about five years. After this time the plant will need to be either discarded and replaced or else lifted, divided and replanted. Finally, there will be times when you see a plant at the garden centre or nursery which you simply must have, even though it means removing an old friend from the rock garden.
Whatever the reason for replanting, do make a good job of it. It is vital that the environment should be right. Nearly all rockery perennials are sun lovers, but a few require shade and these can be accommodated against a rock-face which receives little sun during the day. A few plants cannot stand winter rain on their leaves and should be planted vertically in cracks between the rocks.
When planting a group it is wise to place the pots in position before you begin in order to make sure you are happy with the arrangement. It is customary to plant large specimens before small ones and to place upright, conical conifers at a lower level than spreading ones. The trickiest job is to firm the planting compost around the root ball with sufficient but not too much pressure, use your fingers rather than the back of the trowel.
Many of my early purchases began to spread and I realized quickly that a propagation area was needed. At a market I bought a little wooden propagation stand and set aside a small area in the backyard devoted to new beginnings. This area is near my 'hospital bed' which houses sick plants and I figured this to be the perfect area as there is just the right amount of sun with a portion of shade during the day. Watering cans, plant food and a hose are steps away from this site.
After buying new plants I always save the plastic pots and these are used as little gifts for family and friends. This system affords the opportunity to place my cuttings in an area until I decide the exact location. Several people save the containers and I have a huge collection in the garage. If an unexpected guest arrives they always walk away with a plant. During the summer I propagated many species and used some to plant in new gardens and gave most away. The response has been overwhelming. Receiving phone calls and thank you notes for a plant is very rewarding. One lady told me that the shoot I supplied her with was the only colour she had in her yard for the entire season. She said her thumb is brown, but all of a sudden she can actually grow a perennial and show it off to her friends.
Propagation is practical, fun to learn, saves money, and adds variety to new gardens. This technique is quite simple and put into practice achieves the elimination of bald areas and replaces faltering species. Learning about the proper month to replant, soil requirements, and lighting is crucial and your reward will be a riot of colour in every garden. If your first attempt fails, don't despair. Try again but research the plant by getting advice from your local nursery, books, or check out one of the best resources available at your fingertips the internet.