How to Cut Back a Large Rhododendron

Assess and Plan

• 1

  Make a decision how far back you would like to cut. One good thing about rhododendrons is that there are dormant buds all along the woody stem. Wherever you cut, new growth will emerge from that bud. You can cut it at any height you like as long as there is a dormant bud below the cut point. The plant does not need any foliage on the rest of the branch. Cut it back far enough that you won't have to do another severe pruning for many years. Cutting just the ends off will make it bushy at the top and that probably will not solve the size problem. Be brave!

• 2

  Determine if you want to spread the rejuvenation over a period of a few years or do all at once. If you prefer not to see a bare gap in your bed for many months, you can cut down a third of the branches over a three-year period. That way, the uncut branches will diffuse the look of the bare parts. In the third year, the cut branches will have filled in as you make your last pruning. Alternatively, you can do the entire pruning in one session. It will take some time for the plant to become full again, but it will fill in evenly. Do not expect blooms for two to three years. On the three-year plan, the old branches will produce blooms as usual.

• 3

  Plan the best time to cut for your situation. If you are going to do a severe all-over rejuvenation pruning, the best time is late winter or early spring. This is when the plant will have the most energy to heal the cuts and send energy to the new buds to create new foliage. You don't want to waste the springtime energy to the ends of branches that are going to be cut off. If you are going to do the three-year method, do the pruning immediately after the plant blooms so that you can enjoy the blooms for the season and still give the plant most of the season to recover.

Cut

• 4

  Sharpen your loppers or pruning saw before you start. Sharp, clean cuts that do not damage the bark are best for the health of the plant. If the branches to be cut are over 1 ½ inches thick, use the pruning saw for your cuts. Old rhododendrons may have woody stems close to the base as large as 3 inches in diameter.

• 5

  Examine the branch approximately where you want to make the cut and locate a dormant bud. It will be a small protruding nub on the bark. Select a bud that faces the outside of the plant because that is where the new growth will emerge and the new growth should face outward.

• 6

  Make the cut about ½ inch above the bud. Cut at an angle so that rainwater will shed off the wood.

• 7

  Remove excess branches on the inside of the plant completely at the base to reduce branch congestion. Leave a strong framework of branches but some old unproductive branches can be removed without affecting the density. There may be dead branches to remove as well.

• 8

  Continue cutting around the plant keeping the overall shape rounded and symmetrical.

Heal

• 9

  Apply a fertilizer for acid-loving plants at the recommended dose and mulch the entire area to keep the roots cool.

• 10

  Water throughout the season, but do not overwater. With minimal foliage on the plant, the need for water is greatly reduced. To be safe, put your finger in the soil a few inches to test if it is moist. Only water when it is dry.

• 11

  Prune the plant every other year in the future to maintain the desired size before the plant gets too large for the space. Cut long shoots in half to keep the plant dense and avoid legginess.