When Is The Best Time To Fertilize Arborvitae? – (Best Seasons & Signs)

Arborvitae (Thuja occidentalis) are evergreen shrubs that can be ornamental decorating borders around patios and decks or used in cut flower arrangements. In addition, we can use the flowers of arborvitae in dried flower arrangements.

Let’s look at when to fertilize the arborvitae, the benefits, and how to do it correctly. We will also discuss recognizing the signs of fertilizer burn and how a soil test can help determine proper fertilization for your flowers.

This article is full of valuable tips and will interest beginners and experienced arborvitae growers alike.

What Are Arborvitae?

American Arborvitae
American Arborvitae

These trees grow in moist, deep soil. Arborvitae is tolerant of shade and somewhat drought resistant. 

They are also known for their fantastic needle coverage and exciting bark patterns.

Arborvitaes are grown for their needle cover: like feathery tongues over the enormous boughs of the trees, these leaves also provide nesting sites for woodpeckers and other birds.

The arborvitae family is recognizable by its thick, trunk-like branches that appear in clusters. The branches are round and produce long seed pods. The bark is usually gray or brown, but different varieties may have various colors and textures.

Arborvitaes are not as tall as most trees but can grow up to 50 feet high. Arborvitaes are easy to prune because of their round, dense shape and branching structure. The best time for pruning is in late summer or early fall. 

When Is The Best Time To Fertilize My Arborvitae? 

Arborvitae is a class of plants that is known for its evergreen leaves. These plants can adapt to the soil condition, so they need little water, making them an ideal choice for people with limited time and means to care. 

Arborvitae is usually resistant to pests and diseases, but they still require careful attention.

The most important thing in caring for your arborvitae is choosing tree fertilizers that will be appropriate and doing what you want. 

The suitable time of the year to fertilize Arborvitae is in the early spring before new growth emerges from the plants. It is the only time you should feed arborvitae because doing so at the wrong time of the year could help encourage the plants to put energy into growing instead of the root system. 

It would be best to only fertilize once per year, using a slow-release fertilizer. If you do it in the fall, do it no earlier than mid-September.

Do not fertilize two months before or after the time recommended. Your arborvitae will have a hard time absorbing all of that nutrition. There are some types of fertilizer meant for use in the late fall. The best to choose is high in nitrogen and low in phosphorous. 

Why Is It Important To Fertilize Our Arborvitae?

Fertilizing a tree gives it the nutrients it needs to thrive. But what are the benefits of fertilizing arborvitae? And when should you start caring for these trees? 

Arborvitae needs a lot of nitrogen. A nitrogen deficiency is the most common reason for arborvitae to die back in the winter. If you’re wondering why arborvitae is so hard to kill, they have thick bark and contain plenty of nutrients. 

They won’t just die after one frost; they’ll be fine until next year when you should start fertilizing again.

It is a reason why arborvitae is so hard to kill. We have a tree in our yard planted about five years ago, and it’s awe-inspiring to watch. It’s a great thing to have around because, in the springtime, it blooms and then has beautiful foliage.

What Conditions Are Needed For Arborvitae?

Fertilize your arborvitae according to the amount of sun they receive and whether they need more light. In addition, you should fertilize them according to the amount of rain that falls in their area.

If a site receives a lot of rain and you plant in sandy soil, you should keep it moist but well-drained by mulching with newspapers, or any other eco-friendly material, to prevent soggy conditions. 

On the other hand, if a site receives less rain, it should be kept drier but well-watered regularly to prevent severe root rot. The same rules apply to soil conditions. A heavy concentration of clay in the soil can cause high pH levels that can spell trouble for arborvitae.

The shorter brown Arborvitae on the left has died due to root rot
The shorter brown Arborvitae on the left has died due to root rot – Source: by Jay W, Pscheidt, 2008.

Simple organic mulches such as shredded leaves and grass clippings are excellent choices for keeping the soil loose and erosion-free.

How Do I Know If I Need To Fertilize My Arborvitae?

Arborvitae grown in the right conditions will flourish, but it can be challenging to determine precisely which nutrients the plant lacks.

A soil test will help you determine what nutrients your arborvitae need and how much. A local testing facility notifies you where you can send a part of your arborvitae to find out what it needs.

Ideally, you should test your soil approximately twice a year to check for deficiencies. It ensures that you are using the proper blend of fertilizer and that you are also providing all of the nutrients your plant needs, not just the ones with which you happen to be familiar.

What is a Soil Test?

A soil test is a simple process that can tell you exactly what nutrients and trace elements are in your yard. You do it by sending a sample to a nearby laboratory, where you get the results sent back to you.

Caring For Your Arborvitae

When considering arborvitae for your yard, you should be cautious of where you are placing the tree. It would be best if you did not plant your arborvitae near waterways or exotics, especially in regions where it is invasive. 

For this reason, arborvitaes found in nurseries should not have their roots wrapped in plastic before you buy them.

It would help to plant your arborvitae at least 4 ft. deep and 3 ft. away from other trees or structures. It is best to transplant your arborvitae in the fall after the first frost, but they can be transplanted in the spring if planted later in the day. Also, arborvitae should be watered in a low and slow style for at least a month after planting because it needs to heal.

You may prune arborvitaes yearly, never during the summer, as they are susceptible to diseases. Apply fungicides to the cuts if they are pruned in the summer because arborvitaes do not handle pruning well. Pruning should only occur if dead branches need removal or if there is a risk of falling limbs or branches.

One cause of pruning arborvitaes too much is the threat of infestation. If you notice yellowing leaves, spider mites, or other bugs in your tree, you should have a professional inspect your tree for wood-decaying insects, then treat them before the entire tree is infected.

Arborvitaes can be propagated by themselves when they are young. However, once they are older than five years old, they cannot successfully multiply by themselves. Instead, you will have to buy a plant.

Removing the old, dead branches is simply a matter of pruning as much foliage as possible without removing buds or branches because these features contribute to future branch formation.

Remember that arborvitae are evergreen shrubs and do not need pruning after fertilization. Also, remember to fertilize that arborvitae just before new growth begins in the spring, followed by a soil test to determine proper fertilization for your flowers.

Other Arborvitae Care Tips & Reminders

There are various things you can do to keep your arborvitae healthy. Here are some tips for watering and pruning your arborvitae tree:

(1) If you live in a hot climate, water your arborvitae deeply once a week. It will help reduce the amount of evaporation and also keep the soil moist. In some places, it may not get any water during the summer months.

(2) Keep a close eye on your arborvitae in the winter and protect them from freezing temperatures. Wrap your plant with a burlap bag to keep its root system warm, but remove it before you go outside to play or work in cold weather so that its roots don’t freeze.

(3) When you are transplanting your arborvitae, be sure to water it well. Watering after transplanting is essential because the plant may use some of its stored nutrients while re-establishing itself in the new environment. Plants stressed due to transplanting are more likely to get sick or die.

(4) If you have small arborvitae growing in a sunny window, try moving it outside during the summer months. Use the same amount of water and fertilizer as you did before. You will have to make sure that it gets enough sun during these months.

(5) If you notice your arborvitae is getting sick and dropping leaves, bring the plant inside. If a few leaves are falling off, they will grow back soon. However, if the top of the tree has lost its foliage, it will probably die.

Final Thoughts

We hope this article answers your questions about growing arborvitae. Remember to fertilize your trees properly, and you can see their beauty in their entirety.

Feel free to check out our other articles on gardening!.

About UpBackyard Team

The UpBackyard editorial team is a group of enthusiastic writers with a keen interest in Gardening, Backyard & Home Improvement. We learn a lot & so will you!

4 thoughts on “When Is The Best Time To Fertilize Arborvitae? – (Best Seasons & Signs)”

  1. In section 3 it says be sure to water after transplanting however about 7-8 paragraphs above it says do not water after transplanting for at least a month. Which is better? Thanks for your help.

    • Hi Roger, to clarify, Arborvitae should be watered in a low and slow style for at least a month after transplanting because it needs to heal. (Newly planted Arborvitae require thorough watering to help settle soil around the roots and remove any air pockets.)

      Thank you for your feedback! Our bad! :))

  2. I planted 30 arbs that started out 30-38″. Two of them, side by side, have completely browned within 3 weeks of planting. I’m assuming they’re dead and there’s nothing I can do for them. It’s been 4 weeks since they completely browned and all other trees are doing seemingly great.


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