Do I leave the cuttings outside to root or indoors without lights or with lights? I have attempted to root cuttings from my crepe myrtle with no success. I have cut off approx. 40 - 6" softwood cuttings off my crepe myrtle, cleaned off most of the leaves except the top 3-4 leaves, dipped them into clonex, inserted 20 into rockwool cubes, 20 into a equal mix of sand, perlite and peat. Put all cuttings into a humidity dome kept at 80% with a cfl 26 watt bulb on 24 hrs. After about a week, most are wilted and or dead, some with a bit of a mold or fungus. Have attempted the same with Acer Rubrum "October Glory" 0 success. I just don't get it :-(I have used this same method with vegetables, flowers with nearly 98% success rate. ) What do I need to do different please?
Crepe Myrtle Cuttings
Certified GKH Gardening Expert
If you are seeing fungus and mold, then the humidity and/or heat may be too high for tree cuttings. Tree cuttings can take longer than flowers and vegetables to root. I personally have seen bay tree and fig tree cuttings take months to produce any roots at all when propagating them from cuttings.
I would recommend trying a set outside in summer, without a dome of any kind but kept in a shady location and kept well watered. Also, try keeping the top leaves as you normally do but cut off 1/2 - 1/3 of each leaf to reduce the water lost through them while the rooting process happens.
If you want to try indoors, reduce the humidity some and treat the rooting medium with a fungicide as well, to keep fungus and mold from developing.