Propagation by cuttings.
This is a tuber of Irene Van Der Zweit, a Yellow Lilliput variety. It was started into growth in January and is now throwing about 15 shoots of a size suitable for turning into cuttings. The shoots should ideally be about 5 inches long before cuttings are taken.
Using a sharp knife a shoot is cut just below a leaf node about 3-4 inches from the growing point. When cut the stem should not be hollow, if it is trim the cutting back to the next pair of leaves up the stem.
This is a good sized cutting about 4 inches long.
A pencil or dibber is used to make a hole in the compost of a suitable size for the cutting to be inserted into the compost. The compost should be a fine grade potting or multipurpose type with added horticultural sand of grit. once the cuttings have been inserted into the hole a gentle tap of the pot is all that is needed to settle them in.
Bottom heat of around 20 Celsius will root the cuttings in 2-3 weeks. For those of you without a propagator a good method that works is to saturate the compost in the pot and then seal the pot and cuttings in a clear plastic bag and place on a warm windowsill. rooting may take a little longer.
Part 2. Tuber Division
Ok so we now have a basic understanding of cuttings and what is needed to produce a suitable cutting. We now move
on to the next method of increasing stocks of dahlias, namely division of tubers.
Tuber division is a useful technique if you don’t require vast quantities of plants but just want to increase the number of plants by
say for example 4 or 5 The other advantage is that it is more sucessful for small quantities if you are unable to provide the
correct rooting conditions for a cutting.