Reading Time: 8 minutes 🍃
Japanese Maples, or Acers, are beautiful and popular trees that can brighten up any garden or neighborhood, especially if they’re well fertilized. You may be wondering what kind of soil acers prefer, and what kind of compost they thrive best in. Can you use ericaceous compost for acers?
Acers, or Japanese Maples, do very well with ericaceous compost, as they prefer soil that is acidic and has a pH level of 5.5 to 6.0. If you want to grow acers in alkaline soil, they will need ericaceous compost and some additional considerations to help them grow their best.
Keep reading to learn more about the soil and pH requirements of acers, how to use ericaceous compost with your acers, and the best ways to care for your Japanese Maples.
Can Ericaceous Compost be Used with Acers?
Ericaceous or naturally acidic compost is a compost that is rich in nitrogen and has a lower pH level. Acers absolutely love soil that is on the acidic side and thrive best in moderately wet, forested climates with low-pH, nutrient-rich soils.
Some popular varieties of this beautiful tree include
- A. Palmatum Hogyoku
- A. Palmatum Osakazuki
- A. Japonicum Vitifolium
- A. Shirasawanum Autumn Moon
As a result of their appreciation for acidic soils, ericaceous compost is a great idea for Japanese Maples, especially young saplings who need to grow healthy and strong. The nutrients and plant food found in ericaceous compost can help boost an acer’s growing potential, and give you some truly stunning foliage in the fall.
As acers are hardier and can tolerate a lower pH level than many ornamentals, many soil types can still benefit from ericaceous compost if you’re growing acers, even in locations where a lower pH level might harm more delicate plants.
What Makes Soil Alkaline vs. Acidic?
When we talk about soil being acidic vs. alkaline, we are describing the pH levels of the soil. Materials and substances are described as being anywhere from a 0 all the way to a 14 in terms of being acidic or basic.
For example, battery acid, being extremely acidic, is rated a “0”, while drain cleaner, being extremely alkaline, is rated a “14”. Both are powerful and concentrated chemicals but are opposites in terms of acidity. Pure drinking water is absolutely neutral, at a “7” on the pH scale.
What does this mean for the composition and health of soil? Well, alkaline soils have a pH level of 8.0 or higher and tend to be high in calcium and magnesium. These soils are often clay-rich and common in drier and mountainous terrains.
You may have traveled to a mountain range (or even live near one), and noticed that apart from conifers and scrub brushes, few plant species can thrive in mountain soil. This is because most plant species thrive in neutral to acidic soils, and only a select especially hardy species can tolerate or succeed in drier, alkaline soil.
Acidic soil, on the other hand, tends to be rich in nitrogen, broken-down plant matter, moisture, and nutrients. While we tend to associate acidity with destruction or corrosion in our minds, naturally occurring levels of acidity in soil are a positive sign that the soil is fertile and ideal for growing a variety of flowers, trees, and crops.
Acidic soil is more commonly found in lower to mid-altitude, forested areas with moderate to heavy rainfall and a rich diversity of plant species. Think of deciduous forests and wetlands.
Testing Your Soil’s pH is Simple
If you’re wondering what the pH level is in your garden, testing the pH level is easy. A number of kits and pH meters exist on the market and can be purchased from a home and garden store.
Alternatively, there is a simple test that you can do with your soil and a couple of simple kitchen ingredients. While this won’t give you a specific pH number, it can help you determine if your soil is more alkaline or more acidic.
Take two scoops of your garden’s soil, about one trowel full each, and set them in separate containers. Add ½ cup of distilled water to each separate sample and mix it into the soil thoroughly.
To one sample, add ½ cup of white vinegar, and watch for bubbling and foaming. If bubbling is observed, your soil is more alkaline and will definitely benefit from ericaceous compost if you’re growing Japanese Maples.
To the next sample, add ½ cup of baking soda, and wait for bubbling or foaming to occur. If it does, your soil is more acidic. Even mildly acidic soils can still benefit from ericaceous composts when acers are involved but be sure to test the pH level of your soil.
Soil with a pH level that is already 5.5 – 6.0 won’t need further acidity, as too much acidity can harm the tree. If the pH levels of your soil are slightly higher than this, or neutral, your Japanese Maples can still enjoy the benefits of ericaceous compost.
Ericaceous Compost Feeds and Nourishes Acers
Why do acers love acidic soil? Japanese Maples require a lot of soil nutrition to grow, and this nitrogen-rich earth is typically more acidic in nature. The beauty and color innate to Japanese Maples’ leaves require a lot of nitrogen and natural plant food to become truly vivid and replicate themselves, especially when the trees are young.
Acers also love moisture, especially when they’re small saplings. They can drown in too much water, but moderate amounts of water routinely (we recommend two deep waterings per week for young trees) are much appreciated by these acers, and they’ll do best in moderately wet soils with plenty of drainages.
Ericaceous compost can also help trap the moisture that Japanese Maples love so much, as well as feed the growing plant. So, the combination of nitrogen and water is especially beneficial for these trees, and your acers will benefit most from a healthy amount of ericaceous compost in their first several growing years.
Kitchen Scraps Can Help Feed Your Acer
The good news is ericaceous compost is easy to assemble, and you likely already have some of the basic components in your home or your yard. While you can certainly buy ericaceous compost from the home and garden store, you and your family may enjoy the challenge and sense of accomplishment of composting at home.
Assembling ericaceous compost will require several materials, such as
- Fallen deciduous leaves (oak, sugar maple, etc.)
- Twigs and bark
- Coffee grounds
- Citrus rinds (e.g. lemons, limes, grapefruit)
- Pine needles
You’ll notice that some of these materials, like fallen leaves, already mimic what’s in nutrient-rich soil already. The purpose of this compost is to boost nutrition as well as acidity, and your acers will absolutely love you for it.
Simply allow your compost to “mature” in an outside space, flip your compost every three to four days (this will help the material break down evenly), and use the mature compost when planting sapling acers to give the young trees plenty of rich soil and acid to thrive in.
Make sure the planting hole has good drainage, as well. While Japanese Maples love water, they also need proper drainage to avoid rotting or drowning the root system. Water poured into a suitable planting hole should drain away within 10 – 30 minutes.
Ericaceous Compost Can Be Used Every Spring
While ericaceous compost works best when planting young Japanese Maples, it is possible and beneficial to lightly fertilize your trees with this compost annually.
In the Spring months of April and May, place some naturally acidic compost near the base of the tree, at a radius of about 1 – 2 feet from the trunk in every direction. As the weather warms and the rains arrive, the nutrients from your compost will work their way into the earth and nourish your Japanese Maple.
This is something that can boost the health of the soil and encourage maximum growth and leaf beauty in your acer. Just don’t overdo it with the compost, as too much acid in the soil can harm your maple, too. A one-time application of natural compost in the Spring should be enough to give your acer the boost it needs.
You Can Help “Fix” Alkaline Soil for Acers (Sort Of)
Can you grow acers in alkaline soil? It’s possible, but a bit tricky. Acers are such voracious acid-lovers that the trees will likely struggle in alkaline earth, to the point of being stunted, and exhibiting pale, smaller, and less beautifully colored leaves.
Successfully planting Japanese Maples in alkaline soil will require a few weeks of preparation, as soil pH levels do not change overnight. Begin by breaking up the soil in the space where you would like to plant and disrupt the soil to a depth of about 6 inches. Mix in your ericaceous compost with the native soil, and water the area weekly over the next 3 – 4 weeks.
Next, test your soil’s new pH levels. The combination of nitrogen-rich compost and water will have hopefully lowered the pH levels to a more usable level. This works best in mildly alkaline or neutral soils. Soils that are 8.5 or greater in pH can sometimes take years to modify, and the effort can be time-consuming and costly.
Acidic fertilizers that are store-bought can also be used here in much the same way. If your soil is simply not responding to your efforts to decrease the pH levels, it may be wiser to opt for planting shrubs and trees that prefer alkaline soil, such as
The last option mentioned is indeed a Maple, but it is a bit hardier and more alkaline-tolerant than Japanese Maples and is native to Ireland and the UK. It will yield some beautiful yellow foliage in the autumn and can do well in neutral and mildly basic soils.
Worm Castings Can Improve Alkaline Soil
Another addition to your soil to consider if you’re seeking to lower your garden’s pH level, is earthworms. Earthworms thrive in soil that ranges from 6.0 to 8.0, and their presence, as well as their droppings or castings, can help naturally lower pH levels in calcium-rich soils.
They don’t do well in more acidic environments, however, and it’s not wise or advisable to add worms to your ericaceous compost, as the acid levels of this compost may harm the worms or drive them away into more hospitable soil.
Worms also improve the overall health of the soil, fertilize the earth with their droppings, and break down organic matter within the earth. This makes the soil more suitable for nitrogen and can gradually reduce pH levels.
Other Helpful Tips for Acers
Japanese Maples love nitrogen, rich soil, acid, and mild shade. They don’t require the large periods in direct sunlight that some other species do and will thrive in partially shady spots.
Apart from their love of acidic soil and water, Japanese Maples are pretty hands-off trees. They tend to not require pruning, and if you want to fertilize your Japanese Maple with store-bought products, it’s best to wait a year, to allow the young tree to grow to a size that can better handle commercial products like Miracle Grow.
Here are some more useful tips on how to care for your acers
Japanese Maples also prefer to be sheltered from strong winds and do very well as a part of a larger garden, in which fellow shrubs and trees can help shelter the tree from harsh wind gusts or the brunt of storms.
Japanese Maples, or Acers, do best in acidic soil with a pH level of 5.5 to 6.0. They are, therefore, good candidates for ericaceous compost, which can be applied around the roots during planting, and above the root system each Spring.
Ericaceous compost can be made at home using coffee grounds, fallen leaves, pine needles, citrus rinds, and bark. It can be especially helpful for lowering the pH levels of mildly alkaline soils and potentially making them suitable for Japanese Maple growth.
For stubbornly alkaline soils, it may be best to simply plant trees and shrubs which can tolerate or thrive there, such as lilacs, hydrangeas, and field maples.