All species of the Rhododendron genus place high demands on their location, they only thrive in acidic soil. The trade therefore offers special rhododendron soil. In this article you will find out what you should consider when buying and using and how to mix the substrate yourself.

Rhododendron earth has a relatively low pH

Table of Contents

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  1. the essentials in brief
  2. What is rhododendron soil?
  3. Buy rhododendron soil
  4. Mix rhododendron soil yourself
  5. Use rhododendron soil
  6. frequently asked Questions

    7. the essentials in brief

    • Rhododendron soil is a special substrate mixture for rhododendrons and other ericaceous plants.
    • The substrate has a high nutrient content. Another important feature is the acidic pH value, which should ideally be between 4 and 5.
    • Rhododendrons and other ericaceous plants need a low-lime, loose and humus-rich substrate to thrive and bloom profusely. Normal garden soil with a neutral or even alkaline pH value is not suitable.
    • You can also mix rhododendron soil yourself. In this way you avoid using peat, which should no longer be used for the garden for ecological reasons.

    What is rhododendron soil?

    Rhododendron soil is a substrate specially mixed for the needs of rhododendrons and other ericaceous plants. It is characterized by a low pH and a specific nutrient composition. You can use the soil both to acidify normal garden soil - for example if you want to plant rhododendrons - and to plant these attractive flowering shrubs in tubs.

    properties and composition

    Rhododendron earth is permeable and at the same time stores moisture

    The rhododendron, originally from the high mountains of Asia, needs very special soil conditions so that it can also grow and thrive here. In its composition and structure, rhododendron earth fully meets these needs:

    • loose, airy substrate with high water storage capacity
    • at the same time very well permeable, prevents waterlogging
    • very high nutrient content
    • contains mainly iron, potassium and calcium
    • as well as the trace elements boron, copper, manganese and zinc.
    • contains no lime
    • acidic pH between 4 and 5

    In most gardens, the right conditions can only be created by adding rhododendron soil. Please note that you also acidify the surrounding soil area when using it and can therefore only put acid-loving accompanying plants in the bed.

    digression

    What other plants grow in rhododendron soil?

    In addition to rhododendrons, the following plants also prefer to grow in acidic substrates and can therefore be very well socialized with flowering shrubs: astilbe, bergenia, marshmallow, feather bush, heuchera, hosta, camellia, kerrie, magnolia or cotoneaster. Some berry trees such as blueberries, lingonberries and cranberries also thrive in this substrate.

    What is rhododendron soil made of?

    Depending on the manufacturer and the product, rhododendron earth is composed of different ingredients. These components are often found in commercially available mixtures:

    • peat
    • humus soil
    • wood fibers
    • clay
    • sand
    • the main nutrients nitrogen, phosphate, potassium oxide and iron sulfate
    • Guano (121.99€) or another fertilizer

    tips

    If you want to test the pH of your garden soil before planting rhododendrons, you can easily do this with test strips from the hardware store or pharmacy. For the test, you take a small soil sample, mix it with (lime-free!) water and hold the test strip in. Based on its colour, you can finally tell whether your soil is acidic, neutral or alkaline.

    Buy rhododendron soil - you should pay attention to this

    There are significant quality differences in purchased rhododendron soil

    You can plant rhododendron soil both with and without fertilizer from various manufacturers

    • DIY and garden stores
    • in discounters
    • and on the internet

    to buy. There are significant differences in quality between brand and discount manufacturers. Inexpensive products in particular often rely on ingredients of lower quality, which is later noticeable in the growth and flowering of the plants. However, the peat content of many products is particularly problematic, because raised bog peat is an ecologically extremely questionable component.

    When the peat bogs are mined, valuable ecosystems with rare animal and plant species are irretrievably lost. At the same time, peat bogs are important CO2 reservoirs, and when they are destroyed, CO2 deposits that are millions of years old are released back into the atmosphere and thus have a negative impact on the climate. Therefore, make sure you use peat-free substrates, which are now available from (almost) all leading brand manufacturers. Rhododendron earth from discounters, on the other hand, usually contains large amounts of peat, since the material can be bought very cheaply.

    Mix rhododendron soil yourself

    You can find out what else rhododendrons need to feel good in this detailed and entertaining article:

    youtube

    Instead of using ready-made rhododendron soil, you can mix a high-quality, peat-free substrate for your rhododendrons and other ericaceous plants yourself. For this you need these ingredients:

    • leaf humus: composed largely of rotted leaves, high in nutrients and naturally low in pH; prefer leaf compost made from oak or beech leaves
    • bark compost: low pH value, high nutrient content, coarse structure allows good aeration of the substrate and makes it nice and loose or alternatively
    • wood chip compost: as a substitute for bark compost, has benefits similar to this one or
    • needle litter: the (rotting) needles of conifers provide a low pH
    • fertilizer: here it is best to use well-rotted cattle manure (18.80€) or, if you cannot get hold of them, cattle manure pellets, alternatively a mineral rhododendron fertilizer is also very suitable
    • sand: loosens the earth

    Make absolutely sure not to use any bark mulch, this is too coarse and would not rot in the bed if there was no air. However, you can use the material to cover the planting site. Conventional garden compost is also unsuitable, as it usually has too high a pH value and often contains lime - a deadly mixture for rhododendrons.

    In some recipes, guano is also added as a fertilizer. Of course, bird droppings are an excellent fertilizer, but their environmental balance isn't the best either. Cattle dung is just as valuable, but ecologically harmless.

    If, on the other hand, you have a rather heavy, loamy or clayey garden soil, the additional use of coarse building sand is recommended. This loosens up the structure a bit and ensures better drainage. Rhododendrons do not tolerate waterlogging at all.

    And this is how you mix the rhododendron soil yourself:

    Take a large wheelbarrow and a shovel and mix in the wheelbarrow:

    • two parts leaf compost
    • 2 parts bark compost, wood chip compost, or composted pine litter
    • two parts building sand
    • two parts cattle manure pellets, alternatively rhododendron fertilizer

    digression

    Are bog soil and rhododendron soil the same?

    Yes, bog bed soil and rhododendron soil are different names for nutrient-rich plant substrates with an acidic pH value. You can use both varieties for rhododendrons as well as for other plants with similar site requirements. There is only one difference between individual products: The composition can be different (peaty / non-peaty) or the nutrient content (fertilized / not fertilized).

    Use rhododendron soil correctly in the garden and pot

    Rhododendron soil should not be placed too deep in the ground, because rhododendron is a shallow rooter

    "Plan ahead when planting rhododendrons, as these trees can grow very old and large."

    You can use the purchased or self-mixed rhododendron soil both in the garden and as a plant substrate for tubs. When planting, keep in mind that rhododendrons are extremely shallow roots - so it is no use burying the substrate in the bed or sinking it into a deep planting hole. Here the rhododendrons would not be able to absorb the valuable ingredients because their roots could not reach them.

    The planting hole should only be about 40 to 50 centimeters deep, but wide enough for the spreading roots. It is better to spread the excavated soil elsewhere in the garden, at least if it is soil with a pH value of more than 5. Instead, fill in the rhododendron soil. If necessary, you can dig the planting hole a little deeper and fill in an additional drainage layer. This is useful if the soil in that location is heavy and impervious to water.

    This diagram shows you how to properly create a bog bed:

    In the plant pot, on the other hand, you do not need any further additions, since the ready-made rhododendron soil alone is sufficient. However, make sure that you do not have to add any additional fertilizer for the next six to eight weeks if the substrate is already pre-fertilized.

    frequently asked Questions

    When is the best time to plant rhododendrons?

    As with other trees, the best time to plant rhododendrons is in the fall. Ideally, you can plant the attractive shrubs in the garden between the beginning of September and mid-November at the latest. But planting is still possible in spring, the best weeks are between the beginning of March and mid-May - of course only if there is no frost and the ground is not frozen through.

    In which location do rhododendrons thrive particularly well?

    First and foremost, rhododendrons need loose, very humus and nutrient-rich and, above all, acidic soil. With regard to their light requirements, the trees generally tolerate shade, but bloom more luxuriantly with more light. Therefore, plant them in a location that is as bright as possible, but at least shaded over midday. Rhododendrons are very suitable as underplanting for taller trees, as long as it is not too dark there.

    Can I also plant rhododendrons in normal garden soil?

    In principle, you can also plant rhododendrons in normal garden soil, provided you heed the following tips:

    • bright, light-shady location
    • Garden soil with the most acidic pH possible
    • if the pH is not acidic, add rhododendron soil or leaf humus
    • Dig the planting hole over a wide area and replace the excavation with a suitable substrate
    • Plant rhododendrons together with conifers

    In the long run, the wood does not tolerate ph-neutral or even alkaline garden soil and will sooner or later die without appropriate measures. An exception are new, lime-tolerant INKARHO breeds. These also thrive in normal garden soil and no longer necessarily need an acidic substrate.

    tips

    In order for the rhododendron to grow healthily and bloom diligently, you should supply it with a special rhododendron fertilizer twice a year. This not only provides the necessary nutrients, but also keeps the pH of the soil low.

Category:

Vegetable garden