Vermiculite Useful As Rooting Medium

Press, Volume CV, Issue 31018, 25 March 1966, Page 6

Vermiculite Useful As Rooting Medium

In the initial stages of growth the rooting medium provided for the new plant, whether it be propagated from seed or cutting, can be a vital factor towards its satisfactory development and subsequent form. .John Innes composts are one example of suitable media. Vermiculite Is another.

Vermiculite is obtained from mica being dry heated to 1000 degrees Centigrade. Mica is mined in the Rocky Mountains of Canada. It is made up of water moteculte-Md thin alumina silica plates. With the increasing heat the water expands and vapourises, breaking up the plates with the resulting formation of light, fluffy particles of varying size—vermiculite. It has several commendable features. Its near sterile nature increases the success of germination and rooting in difficult cases and many failures caused by damping off disease are avoided. The absence of

organic matter prevents the development of fungi and bacteria. It has good water and air-holding capacities but, although it is of open texture, it may retain excessive moisture some times.

Its lightness prevents root damage when seedlings are being lifted, an important aspect at this stage of the plant's life when a severe check could be fatal. It is also a useful additive to various soil mixes, imparting greater porosity. It can be resterilised simply by pouring boiling water over it. Here are some compost mixtures:

For germinating seeds: 2 parts vermiculite; 1 part loam soil; lloz superphosphate of lime, plus joz chalk. For rooting cuttings or pricking out: 3 parts vermiculite; 3 parts team soil; 3oz chalk, plus loz John Innes base fertiliser.

In both recipes the fertilisers mentioned are amounts required for a bushel of compost. A bushel is the equivalent of eight full, standard seed

trays or boxes; 22 bushels-27 cubic feet (1 cubic yard). Jeyes Fluid can be used, according to the makers’ instructions, to sterilise ordinary garden soil needed for raising seedlings. Seed trays should never be filled to more than jin from the top and satisfactory consolidation and thorough damping but not saturating of the soil is best done a day before being used.