Container gardens offer gardeners an easy way to add shrubs or other plants to a smaller garden where they may not have lots of space or ideal growing conditions. From kale to green beans to basil, many edible crops are deck-friendly, so why not also grow shrubs and perennials in pots? Even big, beautiful flowering shrubs like rhododendrons can thrive in containers!
Rhododendrons are tough shrubs and staples in many gardens due to their shade tolerance and ease of care. Containers offer a solution for apartment dwellers or renters who don’t have the time or space for a larger garden but still want pretty plants around. Here are 15 simple tips for growing beautiful rhododendrons in containers.
Choose the Correct Container
The most crucial step in caring for rhododendrons is selecting the right container.
Choosing the correct container for your rhododendron is the most important thing you can do to ensure a happy and healthy rhododendron. Look for a container about twice the size of the nursery pot your rhododendron is growing in.
Rhododendrons are shallow-rooted shrubs, so the container does not need to be as tall as it is wide. This helps to prevent overwatering and will keep the cost of filling the container down.
When it comes to the material of the container, this is entirely up to you. Many attractive plastic or vinyl containers on the market will be lighter to move in the winter.
However, ceramic is lovely and durable as well. Another option is using a raised metal bed, such as Birdies raised beds. They offer lovely corner and accent beds perfect for a shrub. Choose a style that suits your patio or landscape.
Prep The Container
Ensure your container is in good shape before planting and caring for your rhododendron.
Before you begin planting and caring for your rhododendron, it is important to ensure your container is in good shape. Washing the container can help remove insect eggs or leftover fungal spores.
Clean out any debris with a sponge or scrub brush, even if the container is brand new. You can use water or a diluted vinegar solution to give everything a really good scrub. Using diluted bleach is another way to clean your pots; just be sure to do so outdoors! Rinse your newly cleaned containers and allow them to dry before getting started.
This is also a great time to examine your older containers. Look for cracks, and patch them if you can. If not, it is time to head out and shop for a new container!
Use Acidic Potting Soil
Most potted plants thrive in potting soil with a neutral pH, but rhododendrons prefer acidic soil.
Rhododendrons are acid-loving plants. Regular potting soil will have a more neutral pH which is great for most potted plants but not ideal for rhododendrons.
Using potting soil specifically meant for acid-loving plants, will give your rhododendrons exactly what they need. You may have some success growing rhododendrons in pH-neutral soil, but it is more difficult for them to grow and bloom properly.
If you live in an area with acidic soil, you may be tempted to use garden soil to fill your pots. Do not add native soil to containers. Garden soil is great for the ground but may be too heavy for containers. It can make the pots difficult to move and can cause drainage issues leading to rot.
Soil Drainage is Crucial
To ensure rhododendrons thrive in containers, provide well-draining soil.
Rhododendrons thrive in well-draining soil. This condition is still required when in containers. There are a few ways you can ensure proper drainage:
- Purchase a container that already has holes in the bottom.
- You can always drill holes yourself with the proper drill bit if needed.
- Use an additive such as perlite or vermiculite to create air pockets and prevent soggy soil.
- Use pot feet to allow water to flow freely out of the bottom of the container.
- Use movable plant bases with drainage holes. They also have wheels to help move the pots around.
Choose the Perfect Rhododendron
When selecting a rhododendron for your container, it is advisable to choose a smaller variety.
Rhododendrons can grow to be very large. When selecting a rhododendron for your container, you may want to choose a dwarf or smaller variety. However, if your heart is set on a larger variety, you can still make it work! You may need to dedicate a bit more time to pruning or transplanting.
For the most part, rhododendrons are hardy in zones 5-8. If you live outside of these zones, you may opt to grow your potted rhododendrons as annuals. Simply remove them from the pots at the end of the season and dispose of them or plant them in the ground to give them a chance at returning next season.
There are so many wonderful rhododendron varieties that would grow beautifully in containers. Here are a few of our favorites to get you started.
‘PJM Elite,’ known for its reliable blooms and cold tolerance, is a highly sought-after rhododendron variety.
5 feet tall
This is one of the most popular rhododendron varieties on the market because it is a dependable bloomer and is very tolerant of cold temperatures. The flowers on ‘PJM Elite’ are a reddish purple and almost appear to glow when the sunlight hits the petals. The leaves are small yet evergreen, keeping your containers looking healthy all winter.
The purple gem rhododendron is a compact variety with clustered purple flowers in ball-shaped trusses.
2 feet tall
This is a pretty purple rhododendron variety that stays nice and compact for your containers. The purple flowers are clustered together in ball-shaped trusses. The leaves are small but brilliant green and evergreen. In the fall, you will get a bonus of bronze foliage for an extra pop of autumn interest.
The ‘Yaku Sunrise’ rhododendron displays hot pink buds that fade to a lighter shade.
2 feet tall
‘Yaku Sunrise’ produces hot pink flower buds that lighten to a paler shade of pink. While this rhododendron blooms, the different shades of pink will give the shrub a bi-colored appearance. The blossoms are large and clustered in pretty trusses which cover the entire evergreen plant.
Plant the crown of a rhododendron plant 2 inches above the soil line to prevent rot.
While situating your rhododendron in your container, ensure you do not bury the plant’s crown. This can lead to issues down the road.
The crown of the plant is where the trunk meets the root system. Burying this part of the plant can suffocate the plant and cause rot. Keep the plant planted 2 inches above the soil line to be safe.
Since you can rotate your container, you need not be too concerned with planting the rhododendron’s best face forward. You can easily turn the container later.
Find the Perfect Spot
A shaded patio or porch is ideal for showcasing rhododendrons, as they dislike excessive sunlight.
Rhododendrons do not tolerate a lot of direct sunlight. When selecting a long-term home for your potted plant, keeping its shady demeanor in mind is essential.
A shaded patio or a porch would be lovely locations to show off your rhododendrons. Another great spot is in a wooded area where you cannot plant anything. Prop your container up on an old stump to give it some height.
Another excellent way to use potted shrubs is in groups gathered together to create a short privacy screen. Depending on your privacy needs, some beautiful evergreen shrubs can hide something unsightly in your yard or give you privacy from neighbors.
Select Companion Plants
Adding perennials to your containers enhances the rhododendron foliage with unique textures.
Adding companion plants to your potted rhododendron is not a requirement. However, if your rhododendron is small or you have extra room in your container, a few companion plants will help fill and beautify a large planter.
Low-growing annuals or ferns will fill the container nicely. Impatiens and begonias love similar growing conditions to rhododendrons and will bloom toward the end of the rhododendron’s bloom time.
You can also add perennials to your containers. Ferns, hostas, or coral bells can provide more foliage to your containers while adding a different texture than the waxy rhododendron leaves.
Time to Water
Container-grown rhododendrons need more watering due to their shallow roots and faster soil drying.
Watering your container-grown rhododendrons will be more important than those growing in the ground. This is because rhododendrons are shallow-rooted, and the soil will dry out quicker in a container.
On average, your rhododendron will need about one inch of water per week. This will be a guessing game until you know your potted rhododendron’s needs.
The main thing to focus on is that the soil in your container is moist but not too wet and does not dry out too much. Remember, these plants are shallow-rooted, and the soil surface needs to remain moist to keep them happy.
Don’t Forget to Fertilize
Adding a layer of compost on top of your container is the easiest way to provide nutrition to your rhododendrons.
The easiest way to give your rhododendrons a boost of nutrition is by adding a layer of compost to the top of your container. Composting is great because you can’t overdo it.
If you prefer to go the additive route, rhododendrons benefit from one or two applications of Holly-tone or another specialized fertilizer for acid-loving plants. These applications should be done in the spring and early fall. Be sure to follow the application guidelines on the label of your bag. You do not want to add too much fertilizer to your container.
Don’t Forget to Deadhead
After your rhododendrons bloom, pinch off faded flowers to prevent seed production.
Deadheading is optional. It does not promote a second bloom in the same growing season. However, it works wonders for cleaning up the appearance of your plant.
Once your rhododendrons have finished blooming, pinch the faded flowers off with your fingers, or use some garden shears if you can’t easily pinch them off. Removing the spent flowers will keep the rhododendron from producing seeds and allow new growth to mature before flower buds form. This will help to secure a prolific bloom in the next year.
Time Up Your Pruning
Prune your rhododendron immediately after it blooms in early summer.
If you need to prune your rhododendron, make sure you do so just after the plant finishes blooming in the early summer. Flower buds will be forming on the shrub in the summer; if you prune too late, you will snip the flower buds right off.
Once you know how much of your shrub you want to cut back, this is an easy process. Using sharp shears, make a clean cut close to a set of leaves.
If you have deadwood or wood that has been damaged, you can cut that back at any point in the season. Cut those branches back as close to the base of the plant as you can. This will allow new growth to fill in any holes this type of pruning may create.
Overwinter Your Shrubs the Right Way
Protect containerized rhododendron from extreme temperatures by relocating the pots to an unheated space.
If you want to keep your rhododendron growing in your container for years, you need to consider how you plan to overwinter the shrub. The ideal way to overwinter your rhododendrons is by moving the pots into an unheated part of your home, such as a shed or garage.
This will shelter the rhododendrons from harsh temperatures that could damage the roots but will still provide a cooler temperature to simulate a mild winter. Do not let the soil in your containers dry out, but do not water them as regularly as you do during the growing season.
Plan for the Long Term
Consider transplanting rhododendrons into the ground or getting a bigger pot as they grow in containers.
Rhododendrons will grow happily in containers for years and years. As these shrubs grow, you may consider transplanting them into the ground or need to get a larger pot. However, you can keep a rhododendron happy in a pot for its entire lifespan if you prefer.
Container-grown rhododendrons are an excellent way to incorporate these shrubs if you don’t have enough space in your garden. These shrubs are reliable and add a unique touch to your container beds. They are long-lasting and very low-maintenance for years to come. Take your time to choose the correct variety for your garden and container, and you will be on your way to success! Have fun planting!