Pacific Rhododendron Plant Profile

Pacific rhododendron blooms

Moelyn Photos / Getty Images

 

Are you looking for a larger plant to be the centerpiece of your garden? Pacific rhododendrons are large shrubs that produce dramatic pink or purple bell-shaped flowers alongside long, thick, evergreen leaves that are sure to capture the attention of any observer!

Pacific rhododendrons are commonly found on the western coast of the U.S. and Canada, where you may spot them among fir trees and redwoods. These beautiful plants can even reach tree-like heights depending on the amount of sunlight received. Common pests include weevils—particularly root weevils.

Botanical Name Rhododendron macrophyllum
Common Name Pacific rhododendron 
Plant Type Perennial
Mature Size 12 to 25 feet high
Sun Exposure Full sun to partial shade
Soil Type Low nutrient; well-drained
Soil pH Acidic
Bloom Time Spring and summer
Flower Color Pink to purple
Hardiness Zones 4 to 8
Native Area Western United States and Canada
Pacific rhododendron growing in forest
Pacific rhododendron exhibiting tall growth pattern Jeff Foott / Getty Images

How to Grow Pacific Rhododendron

Pacific rhododendrons are full and rich with color. Surprisingly, these luscious plants do not need nutrient dense soil, but instead prefer a low nutrient, acidic soil. One thing it likes plenty of is water, and needs well-draining soil. Being cold hardy with its evergreen leaves, these plants can make a statement even in the wintertime. With a balanced amount of partial sunshine and consistent watering, you can enjoy these plants around your yard and in containers.

Light

Pacific rhododendrons thrive best in partial shade to full sun. Did you know that the amount of sun this plant gets can actual change its appearance? With more shade, these shrubs take on a more tree-like appearance. If you want your pacific rhododendron to stay more compact and shrub-like, you can keep it in a sunnier location.

Soil

For such a rich looking plant, pacific rhododendrons actually thrive in low nutrient soil. They do prefer acidic soil conditions, however. If your soil is not very acidic, you can add things like acidifying fertilizers to keep your rhododendron happy. Another option is to keep your pacific rhododendron in a pot.

Water

The pacific rhododendron is a very hardy plant that can survive in drier soil, but prefers to be well-watered. This plant likes moist soil best and appreciates a consistent watering schedule, particularly while it is getting established. To help keep the soil most, try adding mulch to help retain moisture. Although pacific rhododendrons love water, be sure you have well-draining soil to avoid problems like root rot.

Temperature and Humidity

With pacific rhododendrons commonly found in the coastal and forest regions of California, Washington, and Oregon, this plant naturally likes more humid, moderate temperatures. It is quite cold-hardy, and doesn’t mind freezing temperatures, which is clear from the fact that its hardy to USDA zone 4. The only time freezing may be a problem is in the late spring, if the blooming plant gets caught in a late freeze.

Fertilizer

Since pacific rhododendrons thrive in low nutrient soil, these plants do not need to be fertilized often. In fact, too much fertilizer can actually harm them! However, they may appreciate extra nutrients while they are blooming in the spring, making it a good time to fertilize. Be sure to give them fertilizer made for acid-loving plants.

Potting and Repotting

Perhaps your soil is not ideal for your pacific rhododendron, or perhaps you’d rather be able to move the plant around. Either way, pacific rhododendrons grow wonderfully in pots and containers! These plants have shallow roots, so be sure your pot is not too deep and that it drains well. This plant loves water, but a non-accommodating pot can cause soggy roots and root rot. Since it has such a shallow root system, you will most likely be able to keep your new plant in its original nursery pot for quite some time.

When it is time to repot, be sure to choose a pot with drainage holes for proper drainage. Mixing potting soil with grit, sand, or pumice will help expel excess water in the soil and keep your rhododendron happy. Most likely, you will not have to worry about repotting for the first year. Depending on how quickly your plant grows after that, you may have to change the pot every year or two.

Propagating Pacific Rhododendron

Propagating your pacific rhododendron is easy and can be done with cuttings or seeds. Then you can share this beautiful plant with friends or family who admire its happy foliage!

How to propagate with cuttings:

1. Clean a sharp pair of trimmers or scissors, then snip off a stem at the softer woody part of the stem.

2. On each side of the stem, slice a small bit of the bark away. This is called wounding, and will allow the plant to create roots easier.

3. After this, dip the wounded end of the cutting into rooting hormone, and place in moist soil.

How to propagate with seeds:

1. Sprinkle seeds on top of a mix of sphagnum moss and perlite.

2. Place a plastic bag over the pot to help keep them moist. Use small stakes or sticks to keep the bag from smothering the seedlings.

3. Monitor your seeds, rotating occasionally so they can get even amounts of sun on each side. Make sure to keep them away from direct, harsh sun. Once they have adult leaves, or true leaves, you can gradually remove the bag and enjoy your new little plant!

Toxicity of Pacific Rhododendron

One downside to the pacific rhododendron is how toxic it is if ingested. All parts of this plant are toxic to both humans and animals, and can even be fatal. Symptoms of poisoning include:

  • Salivation
  • Watery eyes and nose Abdominal pain Energy loss
  • Nausea and vomiting Diarrhea
  • Weakness
  • Difficulty breathing
  • Paralysis in the arms and legs
  • Coma

Pruning

Pacific rhododendrons are easy to care for, and require very little pruning. Simply remove dead or fading flowers to keep it healthy and beautiful! You can also prune this plant to keep it in a more compact shape as opposed to a more tree-like appearance.