#Japanese Maple Propagation by Hardwood Cuttings

[windfallgardenschenleyfarms]

Japanese Maple Propagation by Hardwood Cuttings 

Culture and Propagation of Japanese Maple

Guy Phillips

Professional Paper submitted to the Faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Master of Forestry

As mentioned previously, hardwood cuttings are those that are taken during the dormant season. For a deciduous species such as Japanese maple, this means that the cutting is merely a stick with some dormant buds that is stuck in a suitable medium. The lack of foliage allows a propagator to forget the worrisome balance between keeping leaf surfaces evenly moist while at the same time maintaining the medium at a state not too moist, and well aerated. For hardwood cuttings, bottom heat is recommended, but air temperatures can remain cool, ideally below the 15.5oC (60oF) range, especially at night. These environmental factors – no misting, moderate bottom heat, and little to no air heat result in a very economically efficient way to propagate. The fact that dormant cuttings are taken during the time of year when nursery activity is all but dormant too, means another kind of economy and efficiency is achieved as well: the economy and efficiency of time. One paper from the annals of the Combined Proceedings of the International Plant Propagator's Society stood almost alone on this subject. I include a summary of it here because I consider the notion of hardwood cuttings of Japanese maple to be of unrealized merit. 

The experiment with hardwood cuttings was begun due to a surplus of grafting scion material. The greatest success has been had with Acer palmatum 'Atropurpureum' varieties. This is the name commonly given to Japanese maples that have red colored leaves of varying shades and retain this trait, in varying degrees, when propagated from seed. Successful rooting and survival of this variety has been between 60 – 70%. However, experiments with the dissected leaf varieties have proven more challenging, as is common for these same types when propagated by softwood cuttings. Success is often as low as 25% (Carville, 1975). 

Cuttings were taken from field stock plants during the first week of January (Rhode Island). Material was between 4.8 - 9.5 mm (3/16 – 3/8 inch) thickness; possessing 2 –3 nodes. The previous season’s growth is taken, ideally as thick as possible, 15 - 20 cm (6 –8 inches) long. Wounds were made, 2 on each cutting, 19 - 25 mm (3/4 - 1 inch) long. Many hormonal solutions have been tried and Jiffy Grow TM was found to be the best. (10 second dip; 29 mL (1 oz.) Jiffy GrowTM to 87 mL (3 oz.) water; Jiffy GrowTM is a mixture of IBA .5%, NAA .5%. boron .0175%, phenylmercuric acid .01%). Medium is a 2 parts peat / 1 part perlite. Medium was slightly firmed and watered; cuttings were stuck; all was watered again then “ignored”. The temperature of the medium was kept between 15.5 - 20oC (60 – 68 ̊F). Air temperatures were kept below 20oC (60 ̊F) at night; no mention of the daytime temperatures. “Excessive top heat and /or overwatering will lead to complete failure, thus my statement to the effect that the cuttings should be ignored. The medium should feel almost dry to the touch and at no time during the first 4 weeks should you be able to squeeze water from a handful of the mix (Carville, 1975, p. 40)" 

Roots appear in about 4 weeks (callus in 15 days). Vegetative buds will soon be swelling after roots have been observed. It is imperative not to overwater during this time. Roots will rot very easily at this point. Newly emerging leaves need shading. A mild fungicidal solution is thought to be helpful in controlling Botrytis fungal infection. By mid- March the rooted cuttings can be potted, perhaps planted into fields directly in milder climates. 3.77 - 7.5 L (1 – 2 gallon) potted plants can be expected to reach 30 - 38 cm (12 – 15 inches) tall by late August (Carville, 1975). 

Carville (1975) concludes by noting, “Unit cost of production is far less than that from softwood cuttings and is considerably less than that from graftage (p. 41).” Another advantage he mentions is that rooted hardwood cuttings are in “phase” with the normal spring time growing conditions and therefore no extra work nor fuss needs to be placed on the necessity of forcing growth before fall, as is the case with softwood cuttings (Carville, 1975). 

I found only one other article on the subject of hardwood cuttings of Japanese maple. A researcher in Poland used Acer palmatum var. atropurpureum (again, this name indicates generic red leaf Japanese maple) to test various times and temperatures of storage of hardwood material prior to sticking into pots of a 1:1 peat and sand medium. It was found that cuttings obtained in November, stored in plastic bags at 55.4 ̊F for 3 weeks and then stored at 35.6 ̊F for 6 weeks worked best. The researcher suggests that the storage period improves callus and root initiation so that the timing of root growth does not lag behind the development of bud break, once the cuttings are stuck (Marcinkowski, 1988). 

January 18, 2024 Nothing to lose trying to root these Red Cut Leaf Japanese Maples cuttings from a branch vandalized & broken off a once beautiful healthy potted tree at Oakland Ave. & Forbes in Oakland.