I love starting plants from cuttings. Not only can you reproduce seedlings or heirloom plants that may not be commercially available, but you can grow dozens or hundreds of plants for free. I started a couple hundred heuchera, rose, and caryopteris plants from semi-hardwood cuttings last year with a fairly high success rate (57% ± 24% across all varieties) even without rooting hormone. However, since I don’t have a misting system to keep the cuttings damp while they root, I had to fall back on labor-intensive hand misting two or three times a day, and I lost two flats of heuchera cuttings to a heat wave. Also, several species (boxwood, blueberries, mock orange, and magnolia) rooted very poorly for me, even though semi-hardwood propagation is recommended for these species.
I need several dozen boxwood plants to line the beds of my newly-expanded formal garden, and I’m not keen on paying $7-$20 per plant at my local garden center, so I decided to try some hardwood cuttings. One to two year old growth was cut from a mature (12 year old) specimen of boxwood ‘green velvet’ in late December and allowed to warm up in the greenhouse until flexible. Branches were pruned into 2″ – 5″ long segments, cutting at a sharp, clean angle to expose as much cambium as possible, and leaves were stripped from the bottom ~1″ of each cutting. Cuttings were dropped into clean water (snow melt) as soon as they were made to keep the cut edge from drying out, and planted in well-moistened potting soil (Milaeger’s brand) in 72-cell flats within about 15 minutes of cutting. I did not use rooting hormone or mist the cuttings – they were simply watered two or three times a week along with the rest of the greenhouse plants. Cuttings were kept in partial sun (4-5 hours per day), at daytime temperatures between 60 ° and 70° F and night temperatures between 35° and 50° F. At eight weeks, 75% (72/96) of the cuttings were well rooted. Success!
This weekend, I started another 121 hardwood cuttings, a mix of blueberry, mock orange, arbor vitae, juniper, and star magnolia. Hopefully, these succeed where semi-hardwood cuttings failed.
If you’re new to propagation from stem cuttings, I highly recommend North Carolina State University’s or the Pacific Northwest Cooperative’s excellent websites for species-specific information and detailed propagation instructions.