How Fast do Rhododendrons Grow

How Fast do Rhododendrons Grow?

Rhododendrons is an ornamental plant and are prized for their showy clusters of blooms and green foliage.  They work best in a partially sunny and shady garden.  It has been said that they can be a hard plant to grow.  How do you grow them?  How fast do rhododendrons grow?  What are some tips on growing them?  Rhododendrons will beautify your garden or home.

How Fast do Rhododendrons Grow

How fast rhododendrons grow will depend on the type as the growth rate varies There are over 800 species of rhododendrons.  There are some varieties that grow two feet each year while others may grow less than an inch per year.  

To figure out the growth rate of your rhododendrons you need to calculate how tall it will be in 10 years and divide by 10.  For example, if you have one that will be five feet in 10 years, you divide five by 10 and you will get approximately a half-inch a year.

In addition, if grown rhododendrons from seeds and not cuttings, then they will bloom slower.  Some samples of the growth rate of rhododendron varieties include:

  • T44 hybrids grew one foot
  • 164 grew two feet
  • 366 grew three feet
  • 281 grew four feet
  • 288 grew five feet

The above growth rate is over ten years according to the online database of The American Rhododendron Society.  They also identify a fast-growing rhododendron as one that reaches a height of seven feet after 10 years. These can include the Mount Everest and Brittenhill Bugle.

Most will purchase these plants that are in full bloom because if you grow them from seeds, it can take two to ten years for their first blossoms.  These plants are capable of growing indefinitely so there is really no limit on how tall they can grow. They generally range in size from giant forest trees to spreading ground cover that is only a few inches tall.

Rhododendron Size Categories

1: Up to 1 footThese are referred to as miniature rhododendrons.  They resemble ground cover instead of bushes.

2:  Up to 3 feet:   These grow from one to three feet and are used as an ornamental plant in rock and flower gardens.  These are called dwarf rhododendrons.  They grow about three inches a year and will reach their maximum height in 10 years.

3:  Up to 6 feetThese are chosen if someone wants to use rhododendrons as a hedge for privacy.  They will grow as wide as they do tall resulting in them looking like a cross between a shrub and a tree.  This group will average growth between six to eight inches each year and it will take them 10 years to reach full height.

4:  Over 6 feetThis category of rhododendron is the broadest category when classifying these plants.  There are some trees that grow as 80 feet tall.  Most of them will be in the eight to ten-foot range.  They can grow as much as one foot per year.  In 10 years, they will reach 10 feet or more.

You can find the largest rhododendron variety in the world growing in India.  It can reach heights of 100 feet.

Rhododendrons Growing Tips

  1. Set the plantsMost of the plants are bought in containers or have their roots wrapped in burlap.  You want to dig a hole where you want them to be planted that is slightly bigger than the container or the size of the root ball.  Set the plant so that the root ball is about two inches higher than the soil around it. Firm the soil around the plant and thoroughly soak it with water.
  2. Fertilizer: When you plant them, they do not need to be fertilized.  If you are going to add mulch around the plant, then it will need a light application of fertilizer.  Make sure you use fertilizer for rhododendrons.
  3. MulchAlthough some do not put mulch on their rhododendrons it is advisable to help them conserve moisture.  Make sure it is heavily mulched.  You can use coarse material like sphagnum peat moss or hardwood chips.  Spread the mulch from four to six inches deep around the plant’s base.  

Rhododendrons should be planted in the spring or early fall when the weather is mild.  You should also make sure that you plant them where they cannot be damaged by the wind.

To reach any of these heights, the rhododendron will need to have the optimum growing conditions, which include plenty of water, gentle or partial sunlight, and mild temperature.  Planting them at this time will give their roots time to acclimate and get ready for spring or to get ready for the winter.

If you are not sure about planting your rhododendrons, talk to the ones where you purchased on how to do it.

How to get Rhododendrons to Grow Faster

When you get ready to plant your rhododendrons you need to make sure that the soil is moist enough and it needs to be kept that way.  You will have to water on a regular basis even if you live in a climate that is moist and humid.  You do not want to drown them but have just enough moisture to keep them healthy and growing faster.  If they do not have the moisture, it can stunt their growth.

Make sure that they get enough exposure to the sun.  The sunlight is what helps create large blooms and large leaves.  The sunlight is what helps to keep them healthy and helps feed them.   Although they need sunlight, they also need some shade. You want the sun to help keep them healthy but you don’t want to fry them either.  

When planting them make sure that they are planted in deep holes so they will have enough room to grow and spread out.  This will help them with long term growth at a faster rate.  If their roots do not have the space to spread out, it will stunt their growth.  The soil should be acidic at a 4 or 4.5 pH and well-draining.


If your rhododendrons have the optimum growing conditions it will reach their full growth potential in both speed and size.  On average they can grow from a half-inch to a foot in a year.  The fastest-growing rhododendrons grew seven feet in 10 years. 

Rhododendrons do not stop growing when they reach a certain height.  If they are well taken of properly, they will continue to grow.  They need space to grow so if you want to have them growing faster and taller, give them two to six feet of space.  With more than one plant, each should have this much space to grow fast and spread.

Some feel that rhododendrons are hard to grow but this is not true. Yes, they do need to be cared for on a regular basis but you will be rewarded with beautiful blooms and fast growth.  They are plants for all seasons with their pleasing colors in white, pink, purple, orange, and yellow, and deep-green leaves.  They can brighten up your home or your garden.  They are great to grow as a hedge for privacy or ground cover.