Rhododendrons and Philodendrons are great plant choices to spice up your garden or your house aesthetics. While both plants require fairly low maintenance when planted properly, they differ in many aspects.
This article will discuss everything you need to know about Philodendron vs. Rhododendron.
Philodendron vs. Rhododendron
Both are plants you can grow indoors. However, Rhododendrons typically form blooming shrubs that are large enough to plant in your garden.
On the other hand, Philodendrons commonly grow in pots, but you can plant them outdoors depending on the species.
Let’s dig deeper into the differences between Philodendrons and Rhododendrons.
Structural Differences
It’s easy to tell Philodendrons and Rhododendrons apart because they have different ornamental features, including:
Leaf Shape
Compared to Philodendrons, Rhododendrons’ leaves are generally small—around one inch.
However, some varieties have leaves that reach three feet long. The leaves have an elongated oval shape with smooth margins.
Philodendron leaves’ shape and size vary depending on the species and maturity. Their leaves can mainly be lobed, oval, heart-shaped, speared, and violin-shaped. They also typically range between six inches to three feet long.
Flowers
Rhododendrons are known for their spectacular flowers with a wide color range, like purple, pink, lilac, cream, yellow, and more. Some varieties produce flowers that have two colors.
The blossoms appear in the early spring until the midsummer, but that can change depending on the climate.
When it comes to blossoming, Philodendrons are a different story. These plants can take up to 16 years to reach maturity, and they flower once a year—usually from May to July.
While it’s rare for Philodendrons to bloom indoors, they flower in their natural habitat or greenhouses when kept under favorable conditions. Their flowers are white or yellowish-white and have a long white part inside of the flower known as the spadix.
Landscape Use
Here are the different ways you can make use of these plants.
Rhododendron
You can cultivate Rhododendrons in your garden under tall trees to add an interesting visual of beautiful flowering shrubs. Rhododendrons also make wonderful foundation plants, and you can even plant them to form hedges.
Some Rhododendrons can even be used as espaliers to decorate trellises, fences, or anywhere you want to hide old walls.
What’s more, you can still pot Rhododendrons and add them to your houseplant collection if you don’t have appropriate soil conditions in your garden.
Philodendron
There are two types of Philodendrons that you can grow: non-climbing and climbing (vining).
Climbing Philodendrons can reach up to 20 feet long, but they’ll need a support structure to climb on, like a wall, trellis, or even a tree.
Potted Philodendrons usually grow indoors, and they can also reach several feet. However, they don’t need a support structure to grow upright.
Cultivation Requirements
Just like all plants, Rhododendrons and Philodendrons require proper growing conditions to grow healthy.
Here are the major cultivation requirements for each plant.
Site
Rhododendrons grow best when kept from the drying wind, ideally, under tall trees like pine. However, don’t plant them near shallow-rooted trees like birch, as this type of root system competes with Rhododendron roots for food and moisture.
For climate conditions, Rhododendrons prefer a climate that isn’t too hot or cold, like in hardiness zones 5 to 8. When used as foundation plants, bear in mind to plant them away from the wind direction and direct sunlight.
Ideally, you should grow Philodendrons in a warm, humid climate with a temperature range between 65ºF–85ºF —in hardiness zones 9 to 11.
However, they can usually tolerate lower temperatures, around 55ºF. Any lower than 55ºF might harm the Philodendrons.
Soil
Well-drained soil with a pH between 4.5 to 6 is ideal for Rhododendron growth. The soil should also be rich in organic matter— it should ideally make up around 50% of the soil.
In addition, you’ll want the soil to contain organic mulch to lock in moisture, improve drainage, and help prevent weeds. However, steer clear of walnut mulch, as they’re toxic to Rhododendrons.
Similar to the Rhododendrons, Philodendrons prefer loose soil with high organic matter content. This tropical plant also prefers slightly acidic soil with a pH range of 5 to 6.
That said, if you’re potting both plants, make sure to change the soil every year or two to avoid salt accumulation in the soil. Increased salt concentration reduces water absorption by the roots and thus limits plant growth.
Light
Unlike the majority of flowering plants, Rhododendrons don’t thrive well when exposed to direct sunlight and grow best in partial shade.
For Philodendrons, it’s best to grow them in dappled light. They also prefer partial sunlight (around four to six hours of sunlight exposure).
Watering
Rhododendrons have shallow roots, meaning they dry quickly during hot summer days. Typically, newly planted Rhododendrons require regular watering about twice a week, and the water should reach eight to 12 inches deep in the soil.
However, you should only water when the soil is dry, as excessive watering will cause waterlogged soil, increasing the risks of root rot. Also, steer clear of hard water since it contains calcium salts that change the soil pH, limiting Rhododendrons’ growth.
Generally, you can water Philodendrons once a week to keep the soil moist. However, you should only feed them water after testing whether the soil is dry or not, as Philodendrons don’t grow well in soggy soil.
Planting Time
Planting Rhododendrons depends mainly on the climate and the variety. As a rule of thumb, it’s best to plant Rhododendrons in the fall if you live in hot areas so that the root system adapts to cooler weather and grows early in the spring.
Alternatively, in cold areas, it’s better to plant Rhododendrons early in spring. That’s to make sure the frost won’t harm them. That said, you can plant Rhododendrons almost all year round in mild weather conditions.
Ideally, you should plant Philodendrons in the spring. However, if you live in a tropical climate, you can plant them any time of the year.
Pruning
While both plants benefit from trimming, they usually require little pruning. When it comes to Rhododendrons, you can cut damaged parts anytime.
However, if you want to shape Rhododendrons, it’s better to wait until they’ve finished flowering.
On the other hand, you should prune Philodendrons in the spring or fall. Still, you can prune them all year round to keep their leggy stems within bounds.
Final Thoughts
If you’re thinking about easy-to-grow plants to add to your backyard or indoor plant collection, you might find Philodendrons and Rhododendrons convenient.
Rhododendrons have small leaves and colorful blossoms and prefer colder climates. Alternatively, Philodendrons grow well in warmer environments, rarely flower indoors, and produce large foliage.
Whichever plant you choose to get, make sure to maintain proper growth conditions to ensure you grow long-lasting, healthy plants!
Growing up with a mom who filled her home (inside and out) with all sorts of plants, Lisa got her start in gardening at a young age. Living now on her own with a home and yard full of plants (including an indoor greenhouse), she shares all the gardening tips she’s gained over the years.