What the propagator calls "half-ripe" cuttings are pieces of shoot a few weeks old; they are not green tips, nor are they firm woody pieces. They can be taken from leading or side-shoots and are generally made about four inches long and inserted firmly about a third of their depth in very sandy soil. Most cuttings are taken just underneath a joint or node, because it is found that roots start freely from a node, but in a few cases - and the Clematis is a conspicuous example - it is better to make what is called an internodal cutting - that is, one severed between the joints. Clematises do not, as a rule, strike freely from cuttings, but if inter-node cuttings are used there will be fewer disappointments. If a cutting forms a large callus but does not root, the callus should be pared down. To ensure speedy rooting it is desirable to put certain kinds in heat. In botanic gardens and nurseries, where a good deal of propagating goes on, the heat is provided by pipes embedded in sand kept moist in propagating cases or frames. The amateur may put his few pots or pans under a large bell glass or handlight in a warm house.
Fig. The Great Rhododendrons Grouped In Lawn Beds. Pink Pearl at Kew. Colour photo by R. A. Malby.
Fig. Methods of Propagating Shrubs
Cuttings of hard wooded plants such as Heaths do not strike readily, and quite small pieces not more than two inches long should be taken.
The following kinds strike best when given close heat:
When the plants have struck they should be fully exposed to the air.
Many kinds do not require heat and root readily if put under a bell glass or handlight in a cool greenhouse or frame. Such are:
Osman thus (peat).
Taxodium (in water).