Last Updated on September 16, 2021 by Grow with Bovees
You’ve decided that you want to go with evergreen trees for a screen or hedge project, or perhaps you just want something that looks nice and is easy to care for, and have settled on arborvitaes as your choice.
Maybe you’ve already procured them and have your spacing and planting already done.
The next questions, of course, are if and when you should fertilize and what the best fertilizer for arborvitae is.
By the end of this article, you’ll have a better idea of the best fertilizer to use for your particular arborvitae trees and which to avoid, how often you should fertilize, what is appropriate for different types of arborvitaes, and how to keep your arborvitaes healthy overall.
So, let’s get to the data that will ensure your arborvitae evergreen plants remain healthy and, well, evergreen.
Side Note 1: Arborvitae is Latin for “Tree of Life”. They grow best in zones 3 through 7, according to the plant hardiness zones map issued by the U.S. Department of Agriculture.
Side Note 2: The arborvitae was the first North American tree introduced to Europe. Its genus name is Thuja occidentalis, with occidentalis meaning “from the west.”
As an ornamental tree, it is very popular for use in mazes, gardens, and cemeteries because of its shape and foliage.
What is the Best Fertilizer for Arborvitae?
Before getting to the ideal fertilizer for arborvitae, it’s probably best to understand why one particular fertilizer is better than others.
In the case of arborvitaes, it comes down to the quality and amount of nutrients in the soil and competition with other plants for those nutrients.
If you’ve decided to plant one or two arborvitaes and that’s it, you should hold off on fertilizing at first. Wait and see if your evergreens thrive with basic care.
Do a quick soil test. Check the soil pH using one of the widely available soil test kits.
Arborvitaes love soil that ranges between slightly acidic to slightly alkaline (or when the soil pH is between 6.5 – 8.0).
If your soil pH is within that range, then you’re good-to-go. However, if your soil test shows it to be out of that range, and you notice your evergreens are not thriving, or if you’ve planted several arborvitae trees to build a hedge or screen, fertilization will be necessary.
This’ll correct the soil imbalance and quell the competition among your evergreens’ root systems for nutrients.
Okay, you’ve decided fertilization is, indeed, necessary. But before you rush out and just buy any old product, you should know arborvitaes, especially newly planted ones, require fertilizers high in nitrogen.
Rather than just going for nitrogen-rich fertilizer, and because your evergreen trees are competing possibly with others for that plant food, a more complete fertilizer may be the way to go.
For arborvitaes, it’s recommended to select fertilizers with a minimum nitrogen-phosphate-potassium (NPK) ratio of 3-1-1.
Ratios will vary between brands, as you’ll see in the examples below, but what you’ll also notice is nitrogen is always the higher of the three elements.
Side Note: arborvitaes don’t require a ton of care or fertilizer, especially as they become more mature. Poor watering, drainage, plant spacing, pests, and diseases tend to be more damaging than a lack of nutrients.
If they’re growing slowly, yellowing, or not very “green”, fertilizing is often the recommended treatment. However, if your arborvitae is turning brown, that could be indicative of something other than a fertilization problem.
Some Brand Examples of Good Arborvitae Fertilizers
Although there are plenty of branded examples of quality fertilizers to choose from that would be more than sufficient to keep your arborvitaes healthy, here are a few that illustrate the differences between brands and also the considerations you need to acknowledge before choosing.
- Down to Earth All Natural Tree & Shrub Fertilizer. (Amazon link) This slow-release product is completely organic with an NPK ratio of 4-2-4. High in nitrogen, which arborvitaes all love, it is also reinforced by mycorrhizal fungi, which are good fungi that help with nutrient preservation for your arborvitae while also encouraging sturdy root development.
The one drawback is, because it is organic, it tends to smell like you would imagine. Also, the natural organic nature of it may act as a beacon for pests and wildlife. But because it is organic, it’s pet friendly and kid-friendly.
- BioAdvanced Shrub Protect and Tree Food. (Amazon link) The drawback of this fertilizer is it only has an NPK ratio of 2-1-1. However, it’s also a slow-release product that is both fertilizer and insecticide. It’s synthetic vice organic but does offer year-round protection. If you live in an area where your soil is already healthy with nutrients, especially nitrogen, and you want ease of use with the combining factor of a built-in insecticide, this may be a fertilizer worth considering. However, it should also be noted, because it is not organic, its synthetic nature may be toxic to pets and kids.
- Plant-tone All Purpose Plant Food. (Amazon link) This product is organic with an NPK ratio of 5-3-3. It’s also slow-release and infused with Bio-Tone microbes, which are essentially food for microorganisms in the soil. Why is that important? Well, it helps facilitate the faster growth of your arborvitaes.
Also, because this fertilizer can be used for a variety of other plants, it may be useful if your arborvitaes share a planting area with others not related to them, such as in a garden bed. Lastly, it is organic, so it’s naturally friendly to kids and pets, but also naturally smelly.
Whether you have acidic soil or alkaline soil, the best fertilizers for your arborvitaes are ones with a minimum NPK ratio of 3-1-1. High nitrogen content will ensure thriving growth, easier care, and an overall healthy arborvitae.
Speaking of keeping arborvitaes happy…
How Often do You Fertilize Arborvitae Trees?
For newly planted arborvitae, it is recommended to plant first, usually in the fall, and not fertilize.
This will give you time to determine how your plant reacts to the soil, your watering, and its new natural environment. It will also give it time to establish a root system before bombarding it with additional nutrients.
Once you have an idea of how your plant is doing and determine it does require fertilization, it is recommended to add fertilizer during the growing season, first in early spring, and continue to do so periodically but cease a few weeks before the first cold or frost.
Side Note: Early spring is also the time of year you’ll determine your arborvitae pruning requirements before heading into summer.
Follow the directions on the fertilizer container for the recommended periodicity of fertilizing for whatever brand you are using and how to distribute it.
More than likely, it will direct you to distribute the granules evenly over the root system area, water thoroughly, and keep away from the tree’s trunk zone.
The specific fertilizer brand’s container will also recommend the amount of fertilizer for each individual tree and whether you should allow it to soak with water into the soil from the surface or mix thoroughly into the soil.
With mature trees, it’s usually recommended to allow them to soak in from the surface, whereas new plantings are usually recommended to be mixed with the soil.
Both will be a few inches away from the tree trunk and over the root zone. Too much and too close to the trunk area can cause plant burn.
Are Slow Release Tree Fertilizer Spikes Good for Arborvitae?
Although granule or pellet-type fertilizer is the most recommended fertilizer for arborvitaes, slow release fertilizer spikes are also useful, especially for mature established plants.
The difference with spikes is the number needed and how far away from the tree they’re located. The older the tree, the more spikes you’ll need.
And because they’re in a constant state of slow release, they need to be placed closer to where you water your arborvitaes. So, for lack of a better phrase, your water line is your spike line.
When Should You Fertilize Your Emerald Arborvitae?
It’s recommended you fertilize an emerald arborvitae up to three times a year between early spring and late June. Again, granule-type fertilizer is the most recommended.
It’s also recommended not to mix it with the soil but let it sit on the surface where it can soak in with watering.
Plant Food to Avoid for Arborvitaes
Below are a few fertilizers to avoid for arborvitaes. They’re more than appropriate for other plants, but not these specific evergreens.
Is Holly-tone Fertilizer Good for Arborvitae Trees?
Holly-tone isn’t appropriate for arborvitae trees. It’s a product designed for acid-loving plants, whereas arborvitae trees prefer more neutral, nitrogen-rich fertilizers.
Is Tree-tone Fertilizer Good for Arborvitae Trees?
Tree-tone fertilizer isn’t good for arborvitaes. It doesn’t have the recommended NPK ratio and is better suited for fruit trees.
How do You Keep Arborvitae Trees Healthy?
The great thing about arborvitaes is they’re not difficult to keep healthy. Soil and water are the main keys to flourishing. Fertilizer helps correct soil nutritional deficiencies, but poor watering, drainage, and plant diseases are the chief reasons arborvitaes fail.
- Mature arborvitaes don’t require much fertilization.
- When and where to plant arborvitaes is just as important as when to fertilize them.
Plant in the fall in an area where it receives enough sunlight.
- Watering and good drainage are key. Low and slow for watering. Moist, not flooded, soil for drainage.
- Good plant spacing is important for proper growth rate and root formation while minimizing competition for soil nutrients and light.
- Keep an eye out for pests eating foliage and diseases (twig blight).
Now you know the fertilizers to use to meet the needs of your arborvitaes and ones to avoid; when and how to fertilize; and common issues that can affect overall health.