A
breeder for roses will cross-breed from a stock of 10,000 genetically different
parents. From these it is likely that only three or four possible
commercial varieties will become available. These three or four varieties
are finally selected for yield, colour and shape, leaf and stem
quality,
vigour, behaviour and vase life. Once these varieties have been selected
there is a process of multiplying up the genetically identical
material for further commercial trials before a variety is available
on the market for growers. This process may take several years.
Once a particular rose variety has been selected enough stems have to
be found of that particular variety to cut into 12-15cm pieces known
as bud-wood. These will then be grafted onto the rootstock (the
base of the top-graft), a process known as top-grafting.
There are several types of rootstock, but in Kenya only two or
three types are typically used. The quality is vitally important.
It must be absolutely pure and virus free and can affect all the
components that a breeder looks for in the breeding programme including
colour.
Following this process the rootstock is dipped into a rooting hormone
placed in a cocus media under warm, high humidity conditions to
allow the plant to produce its own roots. This will take between
five and six weeks. Once the plant is rooted and established it
is ready to be transferred to the greenhouse.
In the greenhouse between six and eight plants are planted per
square metre, either into raised bed formats or into a controlled
media such as cocus, rock wool or pumice (hydroponics).
Each rose plant is individually fed and watered on a continual basis.
Under the regular and reliable Kenyan sun the first cut flower stems
will be ready to harvest within three to four months.
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