Optimizing Container Production and Propagation Protocols for Five Underutilized Northeastern United States Native Shrubs

Corylus cornuta, Lonicera canadensis and Viburnum acerifolium are underutilized native shrubs with ornamental potential that are often found growing along roadsides in dry, gravely soils. One-gallon nursery containers with media composed of four parts aged pine bark, two parts sphagnum peat moss and one part sand, was amended with expanded shale at 20% and 50% to produce growing media resembling the natural soil in which these plants are found. Two rates of topdressed controlled-release 15N-3.9P-10K fertilizer (OsmocoteÒPlus 8 – 9 month formulation), 1 g N and 2.5 g N, was also evaluated. Expanded shale did not improve plant growth for these species, and significantly larger plants of L. canadensis were produced in control media (lacking expanded shale) than in amended media. For all species, there was no significant difference in plant size for the two fertility levels. One-gallon containers of C. cornuta and V. acerifolium in un-amended media were 35 to 40 cm tall, 25 to 30 cm wide and had 4 to 7 shoots. One-gallon containers of L. canadensis were 40 cm tall, 50 cm wide and had 9 shoots. In a separate study with V. acerifolium in one-gallon containers, plants were pruned to 14 cm or left un-pruned (35 cm). At the end of the growing season, pruned plants were shorter (30 cm) than un-pruned plants (50 cm), but visual quality ratings were two times greater for pruned plants, because they had equivalent height and width and a more symmetrical and full appearance. Softwood stem cutting propagation was conducted using three rates of indole-3-butyric acid (IBA) in talc (1000, 3000, and 8000 ppm) and a no hormone control for Eubotrys racemosa and Viburnum lantanoides. E. racemosa rooted at 100% and cuttings treated with 1000 or 3000 ppm IBA had significantly longer roots than the control. Due to its ease of propagation, adaptability to tough landscape conditions, and ornamental features including attractive red fall foliage, E. racemosa has the potential to become an important landscape plant and be utilized as an alternative to invasive Euonymus alatus. V. lantanoides is desirable for its outstanding ornamental traits, but it is reported to be difficult to propagate from cuttings. However, we achieved greater than 80% rooting for IBA-treated cuttings, and cuttings receiving 3000 or 8000 ppm IBA produced more and longer roots than the control. All five species could be viable commercial crops for nurseries looking to add native shrubs.