When should I cut back angel’s trumpet and can I replant the part that was cut?
I’ve checked a book called Brugmansia and
Datura: Angel’s Trumpets and Thorn Apples by Ulrike and Hans-Georg Preissel.
It has a whole chapter on growing angel’s trumpets from cuttings as well as a
section on pruning them, which should be done after they bloom. As you probably
know, they can’t take freezing temperatures, so people often prune them in the
fall to make them easier to bring into a greenhouse (for overwintering warm) or
41-50 degree room (for overwintering cool). The important thing to remember is
to confine your pruning to the flowering part of the plant, so you don’t have to
wait as long for more flowers. The book says you can tell the flowering part of
the plant by looking closely at the leaves–the flowering part has an
asymmetrical leaf base on each leaf, but the base of the “vegetative” leaves is
symmetrical.
The cuttings you take can be used to start new plants, and the success rate will
vary depending on the time of year (spring and summer cuttings work best) and
the variety of angel’s trumpet you have. Viruses can be a problem, so keep your
shears very clean. You can often get them to form roots by placing them in a
jar of water so that only the lowest 1.5 inches of the stalk are under water.
Alternatively, place woody fall cuttings “about 10 inches long…in a mixture of
peat and sand, in vermiculite, or in pumice… temperature between 53 and 64
degrees… Many of these cuttings will form roots by the following spring. For
root development the cuttings need the same light levels as for good growing
conditions… It is a good idea to pot all cuttings into a nutrient-rich soil as
soon as possible after they have formed roots.”