5S? Universityof Idaho OCT College of Agriculture Current Information Series No. 532 Cooperative Extension Service April 1980 pAgricultural Experiment Station Propagating Ornamental Trees and Shrubs A. A. Boef Professor, and T. J. Bakken, Research Assistant Department of Plant and Soil Sciences Commercial propagators have elaborate facilities — the trees and shrubs most commonly grown as orna for propagating trees and shrubs grown as ornamen mentals. The serious hobbiest can find more complete tals. These are necessary where the propagator must information in a number of good plant propagation have a high percentage of success if he is to make a books. living. Definitions The home gardener and hobbiestcan, however, do a tolerable job of propagating trees and shrubs with Here are definitions of some terms used in plant little or no equipment. The processes of rooting, graft propagation: union formation or seed germination might not be as Stratification — moist treatment of the seed, usually successful as in commercial facilities, but usually the at 40° F (4°C) but sometimes also at warmer tempera- hobbiest will only want a few plants of each kind. paper or with concentrated sulfuric acid. The rooting hormones can be purchased at garden Stratification — moist treatment of the seed, usually stores or a local nurseryman may have special concen at 40° F (4°C) but sometimes also at warmer temera- trations if needed. Bottom heat can be supplied by an tures. The seed is usually mixed with moist sand, ver- inexpensive heatingcable. Small plastic shelters setup miculite or peat and placed in flats or plastic bags. in a shady part of the garden can substitute for the Hardwood cuttings — cuttings taken during the greenhouse environment. For summer or softwood cuttings, a lathhouse or even a shady spot will suffice. dormant season. Mist maybe applied by hand 3 or4timesa dayto keep Softwood cuttings — cuttings made from growing the cuttings turgid and cool. shoots. Seeds may be collected and then stratifiedina home IBA — indole butyric acid, a plant hormone used to refrigerator, or they may befall-planted to satisfy their induce rooting. It is usually formulated at various con cold requirement. Young seedlings may beshaded with centrations in talc. It may also be used as a liquid quick lath or snow fencing for the first few weeks. dip (concentrated) or soak (dilute) treatment. The publication summarizes methods of propagat Bottom heat — heating of the rooting media usually ing —byseed or by some form ofasexual propagation with electric cables. Ornamental Trees and Shrubs Genus Genus Propagation (Common name) Propagation (Common name) Seed —• Use fresh seed. Stratify I to 3 ripe. A palmatum seed will germinate Abies after being soaked overnight in hot water. (Fir) months at 40° F (4°C) or plant in the fall. Cuttings —Take in winter. Treat with .4% A. circinatum requires an extended strati or .8% IBA. Use bottom heat. fication period. -K Graft - Side-graft onto seedling of same Cuttings —Summer cuttings ofA.ginnala species. and A. palmatum root readily when 0 treated with .3% IBA. Use mist and bottom Acer Seed — Stratify at 40° F (4°C) for 90 days heat. Overwinter cuttings in a greenhouse <W* (Maple) or fall-plant. For spring seeds (A. rubrum or frame. and A. saccharinum), plant seed when Genus Genus (Common name) Propagation (Common name) Propagation Acer (continued) when treated with 15 to 25 ppm IBA for 24 hours and placed in the greenhouse under Grafting — Cultivars of the maples are mist. Root cuttings can be taken in the fall bud-grafted onto seedlings of the same and stored at 40° F (4°C) overwinter. They species. Grafting is done in late summer. are lined out in the field or potted in the Budded cultivars should be used in prefer spring. ence to seedling trees because of their uni Chamaecyparis Cuttings — Cultivars of C. lawsoniana are form growth habit. (False Cypress) hardy in most of Idaho. Cuttings root if Aescuhis Seeds — Gather seeds and stratify im treated with .3% IBA and benched from (Horsechestnut, mediately at 40° F (4°C). Field plant in August to February. Bottom heat aids Buckeye) rows or grow in 2 gallon containers. rooting. Cuttings placed in a cold frame in Alnus Seeds — Stratify at 40° F (4° C) for 60 to 90 fall will root readily the following spring. (Alder) days or field plant. Clematis Cuttings — The popular clematis vines are Arctostaphylos Seed — Try stratification for 3 to 4 months (Clematis) propagated by cuttings, usually taken from (Kinnickinnick, at 40° F (4°C). Germination will be erratic. greenhouse stock plants. Treat with .3% Bearberry) Cuttings — Take any time from August to IBA, or quick dip in 2000 to 4000 ppm, or March. Treat with .3% or .8% IBA. Use soak in 25 to 50 ppm for 12 to 24 hours. Use peat-sand, peat-perlite media and bottom mist and bottom heat. heat. Cornus Seed — Harvest berries when ripe, extract (Dogwood) seed and stratify immediately. If seed is Artemisia Cuttings — The artemisia used for orna (Sagebrush) mentals are propagated by cuttings which dry, as from commercial sources, soak 24 root easily when placed in a well-drained hours before stratifying. Stratify at 40° F but moist media. (4°C) for 4 months. Cuttings — Softwood or hardwood cut Aucuba Cuttings — Summer or fall cuttings root tings of C. stolonifera, C. alba root readily. (Gold Dust) easily. Use .3% IBA and bottom heat. Treat softwood cuttings with .2% IBA and Berberis Seed — Stratify 60 days at 40° F (4°C) or root under mist. Hardwood cuttings may (Barberry) fall plant. be taken in February or March, treated Cuttings — Root leafy cuttings under mist with .3% IBA and rooted on a bench with in mid-summer. Use .3% IBA and bottom bottom heat. heat. Grafting — C. florida is grafted onto seedlings. Betula Seed — Stratify 60 to 90 days at 40° F (Birch) (4°C) or fall plant. B. papery/era should be Cotinus Cuttings — To propagate pistillate plant frozen 4 to 6 weeks and then planted. (Smoketree) used as ornamentals, softwood cuttings are Graft — Cultivars of birch, primarily taken in early summer. Treat with .3% IBA B. pendula, are bud-grafted onto root- and root in greenhouse under mist. stocks of the same species. Cotoneaster This group of ornamentals is variable in Buxus Cuttings — Make cuttings in fall. Treat (Cotoneaster) propagation. Seed propagation is gener (Boxwood) with .3% IBA and use bottom heat. Soft ally unsatisfactory. C. horizontalis can be wood cuttings may also be rooted under grown from seed. Scarify in sulfuric acid mist. for 1 to \Vi hours and stratify at 40°F (4°C) for 4 months. Other species are best Calluna Cuttings — Summer in greenhouse (also propagated by cuttings. C. dammeri roots (Heather) in fall). Treat with .3% IBA or soak 24 easily as either softwood or hardwood hours in 50 ppm IBA. Root in peat-sand cuttings. C apiculatus and C. microphylla media. Bottom heat may help. can be rooted as softwood cuttings in Caragana Seed — Soak seeds and sow in field or August. Use .5% IBA. (Siberian Pea) stratify 60 to 90 days at 40° F (4°C). Crataegus Seed — Complicated seed dormancy. Castanea Seed — Stratify immediately after harvest, (Hawthorn) Stratify warm 70°F (20°C) for 3 to 4 (Chestnut) 3 months at 40° F (4°C). months, then 40° F (4° C) 3 to 4 months, or Grafting — Cultivars of Chinese chestnut scarify with sulfuric acid 15 to 20 minutes are budded or grafted onto C. mollissima and then stratify at 40° F (4°C). rootstocks. Grafting — Cultivars of C. laevigata (C. oxyacantha) are grafted onto seedlings. Catalpa Seed — Require no treatment. Store cool (Catalpa) and dry overwinter. Plant in rows in spring. Cytisus Cuttings — Can be rooted most any time (Scotch of the year, best in August to December. Seed — Place seed in hot water and let sit Ceanothus Broom) Treat with .3% IBA and give bottom heat. (Buckbrush, for 24 hours. Sow in beds. Stratification at Red Twig, 40° F (4°C) may be necessary for C. Daphne Cuttings — Leafy cuttings in June and Ceanothus) sanguinea. (Rock Daphne) July. Root in peat-sand media. Treat with .3% or .8% IBA. Use bottom heat and mist. Celtis Seed — Soak seeds 10 to 30 minutes in con (Hackberry) centrated sulfuric acid and plant into beds Deutzia Cuttings — Both softwood and hardwood (fall) or stratify at 40° F (4°C) for 3 to 4 (Deutzia) cuttings root easily. IBA treatment may be months for spring planting. helpful. Mist softwood cuttings in the greenhouse. Chaenomeles Cuttings — Although seed are easy to ger (Flowering minate, cultivars are maintained by cut Elaeagnus Seed — Stratify 3 to 4 months at 40° F Quince) tings. Early summer cuttings root readily (Russian Olive, (4°C). Genus Genus (Common name) Propagation (Common name) Propagation Silverberry, Cuttings — Softwood or hardwood can be Larix Seed — Fall plant or stratify at 40° F (4° C) Autumn Olive) rooted. Softwood taken in early summer (Larch) for a month. and rooted under mist does best. Cuttings — Root young tips in early sum mer. Use .8% IBA and mist. Erica See Calluna. (Heath) Ligustrum Cuttings — Root softwood or hardwood Euonymus Cuttings — Root deciduous kinds from (Privet) cuttings. Hardwood cuttings taken in late (Burning Bush, softwood cuttings; evergreen kinds any winter will root in the greenhouse or can be Winter Creeper, time. Root easily. field rooted. Spindle Tree) Lonicera Cuttings — Most root easily from hard- Fagus Seed — Do not allow to dry. Stratify at (Honeysuckle) wood cuttings taken in late winter. Use a (Beech) 40° F (4°C) for 3 to 4 months.