Notes from WRRC - Propagation Techniques

2013 Western Regional Rhododendron Conference, American Rhododendron Society

Newport, OR Sept 27-29

"Cuttings"

-Rooting mix: 40% fine fir bark, 10% sharp mason sand, 10% peat

1. Look for eyelets on clipping.

2. Clip pencil sized sticks or smaller.
3. Trim top leaves about 1/3 or 1/2.
4. Score one side.
5. Dip in rooting hormone.
6. Stick in 2" pot filled with rooting mix.

-Keep bottom of pots warm, 70-75 degrees, with high humidity, good if top of plants cooler.

-Do deciduous azaleas in the spring, keep wet and cool over summer.

-Spray vinegar to kill liverwort.

-Once there are roots, transplant to gallon pots.

-Transplant mix: fir bark with zeolite (kitty litter), 25 lbs/cuyd bark.

-Fertilize after transplant, one year slow release Apex 20-4-7+iron add Epsom salt too.

"Air Layering"

Use if difficult to propagate from cuttings, or if bush is dying.

Tools: clean pruners, clean sharp knife, scissors, damp spagnum moss, fine bark, black garbage bag, cable ties.

1. Choose a branch 12-24" long, sturdy enough to support materials, out of the sun and upright as possible.

2. Cut garbage bag into strips about 10" across.

3. Chop up moss (blender works good). Make rooting mix: 1 part fine bark to 2 parts moss. Mix together with water until wet.

4. Wound the branch. Cut a 3-4" wound down branch to expose the cambium layer, remove the tongue.

5. Use one hand to form the rooting mix around the wound and the other hand to wrap the garbage bag around the rooting mix. Form a tube around the branch, secure with zip ties at top and bottom. Do not make too tight, but also do not leave any air pockets inside the wrapper. Zip ties should not damage the bark on the branch. Water should be able to enter the top and drain out the bottom.  Wrap should look like a Christmas Cracker.

6. If the main branch is bends too much, secure it to another branch using longer ties or support with stakes.

7. Wait. The process may take 2-3 years for roots to form enough to transplant.

8. Maintenance: make sure ties are not too tight, water during hot, dry weather. Replace the ties each spring and autumn. For plants that are dying, fertilize wrap with diluted tomato fertilizer twice a year.

9. After two years, lightly squeeze the wrap. If it feels soft and pliable, leave it for another year. If it feels firm, cut ties and carefully unwrap plastic. Rewrap and leave for another year if there are few roots or if they are small.

10. When roots are mature, cut the branch about an inch below the roots. Carefully tease out the roots and spread them out in 1ga container. Plant diagonally across pot, use a stake to support the plant. Plant in chopped bark. Keep container in cool shade for another year.

Also able to layer in soil in moderate climates. Use a stakes to bend a branch to the ground, score and leave alone, as above.