Posted: 22/04/2014 at 21:14
Hello Catie. My, you are very adventurous. As has been posted. Propagating rhododendrons is along job. Basically there are four methods used. Seeds. Layering. Cuttings and grafting.
Seeds are sown in February or March. Compost should be horticultural peat that has been very finely sieved. It is OK to add a reasonable measure of sharp sand. Half-pots are the best containers. Lightly cover the seeds with silver sand or vermiculate. The compost must be kept moist all the time. A heated propagator is useful or heated frame. Temp; about 16 deg. C. No heat, then delay sowing until late April Layering can be done virtually any time. Low branches are pegged down and covered with soil/compost. Some people will make a slanting cut just below halfway through. Then as the section is being pegged down.. The cut will open slightly. After about two years, it should be safe to cut the layered plant away from the parent. Potting up or planting out into a nursery bed, containing plenty of peat,or peat substitute and lef-mould. Air layering does work, but it has many disadvantages.
Cuttings can be taken during the second half of the year. It is advisable to check on the variety, as some prove better than others.
Grafting. Gafting isn't quite as easy and straight forwards as some might think. To graft rhodo's, a method known as Saddle Grafting is used. For this, you must have a rootstock. This is always a rooted R.ponticum. That's what most call, the wild rhodo. It is easier to work on a bench, with the rootstock out of the soil. Take the stem of the rootstock and using a very sharp knife. slice the stem on opposite sides. This should look like an upturned V= ^ Then you have to cut the base of your cutting so that it fits, tight and snug over the ^. Then the whole joint is bound and tied. The method used to consist of binding with bass or raffia. Now possibly a wax sealant might be used. The newly manufactured plant can be potted up/planted. Sad to say, as with many of the exotic trees and shrubs. From start to finish something in the region of 4-6 years can pass, before you have your masterpiece. In their natural surroundings, often the seasons change much faster than ours in the UK. This seems to influence propagation. A final point. For anyone wishing to attempt these methods. I admire your zeal. However do as many as you can. For the amateur, if you get one in fifty say, that take and finally adorn your garden. I take my hat off to you.