Rhododendron Care and Culture
By Al Fitzburgh

The most important factor in successful rhododendron culture is selecting the best planting site. It should be under high shade of deciduous trees, and if possible, on a north or east facing slope. Maples and beeches are too root competitive for successful planting. The ground around the site should be well drained, but improved with organic matter if it is not already in the soil.

Dig the hole about 12" to 18" deep and 3' in diameter. If the soil is a sandy loam type no other change is necessary, if it is not, amend the soil with pine bark mulch and/or peat moss (1/2 original soil to 1/2 pine mulch).

Prepare the root ball by removing excess soil and exposing the roots in the perimeter of the root ball. Place the prepared root ball in the planting hole with a few inches of the prepared mix at the bottom of the hole below the roots and back fill with the rest of the mix. Do not tamp down the soil but do water it immediately with a slow flow of water until it runs out of the top of the hole. Do not fertilize for a year but do keep the plant well watered if it doesn't rain for at least a week.

Additional Information

1. Be sure that the root ball is opened up. If the plant was in a container and the roots have circled the root ball and girdled it, take a small rake type hand trowel and pull apart the root ball until the roots are open at the periphery of the ball.
   
   
2. Have a soil test done by your county agricultural agent or by Rutgers Soils Lab, PO Box 902, Milltown, NJ 08850 for pH etc., and amend for most plants to a pH between 5.0 and 5.5.
   
   
3. Install a watering system such as overhead sprinklers, leaky hose, etc., and automate it with a timer.
   
   
4. Be careful of sprays for fertilizers and insects. Always check the dosage and time of application and lean toward cutting the application rate. I have killed more plants with too much fertilizer than I have ever stimulated into better growth. If you are in doubt as to whether to fertilize or not, then DON’T.
   
   
5. The best time to plant is in late August or early September. This gives the plant the most time to establish roots before the ground freezes. The second best time is in March or as soon as the ground can be worked. Never plant a plant after October 15th, or after May 1st. If you have gotten a plant after those times plant it in the ground in its container until a more favorable time.
   
6. Try to prune plants just before April 15th to take advantage of new growth spurts. You will lose some flower buds for the year but unless the flowers are important to you at that time you will have a better-shaped plant for the future.