Arborvitae are fragrant evergreen trees that display bright green leaves during their spring growth that then deepen in color as they age. These drought-tolerant trees are frequently used to create a natural windbreak, hedge, or privacy screen, and once established, they’re generally considered low maintenance. Healthy arborvitae will grow between 12 and 24 inches per year, and depending on the variety, they can grow to 40 to 60 feet tall with a 10- to 15-foot spread.
They prefer full sun to partial shade and require at least six hours of direct sunlight daily. The densely packed fragrant leaves delicately overlap and splay to fill the interior, and rows of branchlets create a full body. They naturally grow in a conical shape, but shaping and trimming arborvitae is well tolerated.
There are a number of different considerations to be made when caring for your arborvitae throughout the year, and factors such as soil condition, water requirements, root health, and direct sunlight may fluctuate during different seasons. Also, should you be fertilizing? Is pruning or trimming arborvitae something you might call a professional, such as Mr. Tree, to do for you? Even trees generally considered “low maintenance” are not “no maintenance.”
Your healthy arborvitae will live between 50 and 150 years with minimal effort overall. It’s an evergreen, meaning that the tree will remain green throughout the year. However, they do have branchlets that may yellow or brown in autumn. The oldest branchlets die off, then shed normally, and space is created for the next spring’s growth. If you find your arborvitae is excessively brown, you may have a more significant issue.
If you suspect that there’s more going on than simply seasonal dehydration, you can contact a professional to come inspect your tree. Arborvitae are also quite sensitive to wet, poorly draining soil, and they can easily develop root rot, which can kill a tree entirely. These are some common diseases that affect arborvitae:
- Branchlet disease—This is considered normal browning, and can indicate severe drought conditions or root rot. The branchlets turn brown and fall off.
- Kabatina twig blight—This invasive fungal infection begins by killing the tips of the younger branches, after which it spreads to larger branches. Branches turn brown or ash gray.
- Pestalotiopsis tip blight—This fungal infection turns twig tips tan to brown.
- Phomopsis twig blight—This is a different type of fungal infection that also turns branches brown or gray. Arborvitae can be infected with both Phomopsis and Kabatina at the same time. Fortunately, they can be treated the same way.
The general recommendation for trees with fungal infections is to prune and destroy all infected twigs and branches, apply a fungicide, and avoid watering leaves or branches to inhibit spore germination. Regularly pruning and trimming arborvitae will ensure that there’s ample airflow to adequately dry wet leaves and branches, and annually clearing castoff leaves and branches from the interior will reduce potential disease and pests.
There are some fundamental needs for arborvitae. The best soil for arborvitae is moist, well-draining, acidic loam. It’s best to test your site soil before planting, and if it retains too much water, integrate some grit for drainage. Feeding is usually unnecessary, but watering is important during the first year, and then whenever the top two inches of soil are dry.
Also, roots benefit tremendously from mulch protection. With respect to sunlight, your arborvitae needs a minimum of six hours of direct sunlight, and prolonged periods of shade can be detrimental to the fullness of the tree. Different seasons offer different challenges, but with some planning, you can be sure your trees are well cared for.
Springtime is a prolific time for plants and animals alike, and when spring arrives, there are a few things you can do to encourage lush growth during this season. Once you have made your cultivar choice based on soil, light, and personal style, give your new arborvitae its best chances by planting it early in the spring. This will give the tree valuable time to establish its roots before the cold of winter arrives.
A mature tree may substantially benefit from early spring fertilization and can be fertilized annually using a slow-release granular fertilizer. It’s important to follow with a deep watering to ensure that the fertilizer is dissolved and available to the root system. Early spring is also a good time for pruning and trimming arborvitae. You’ll want to avoid cutting branches back behind the green foliage unless it is broken. If you encounter broken branches, make a clean cut approximately six inches above the breakpoint.
For first-year trees, you’ll want to water regularly to ensure the soil remains moist, but take care not to overwater, as soggy soil can lead to root rot. When necessary, water only as much as required to keep the root ball and adjacent soil moist. It’s important that during the initial growth period the tree is also protected from dry soil. Once it’s well-established, arborvitae will have good tolerance for dry conditions where it’s only necessary to water after long periods of drought. If you find limp foliage and yellowing leaves, these can indicate your arborvitae would benefit from a good deep soak. You can find some additional watering tips here.
During the fall season, your arborvitae will likely exhibit some browning leaves and dead branches. Despite being evergreen, arborvitae trees are subject to annual growth and death cycles. Because of the conical, dense structure, branches will frequently fall and settle at the base of the trunk. You can selectively prune dead material, but be sure that you have completed trimming arborvitae at least two months before your expected first frost. This will give your tree an opportunity to heal before the stress of winter hits.
For first-year trees, it’s unlikely you will need to do much beyond the recommended watering. During periods when the ground is warm enough for water to penetrate to the root system, give your arborvitae a deep watering. Allow water to penetrate the top 8 to 12 inches of the soil in the entire root zone. Don’t forget the mulch. The combination of deep watering and mulching will significantly reduce evaporative water loss. Much of the winter burn that affects arborvitae is probably a result of dehydration because the hard, frozen surface prevents water from penetrating to the roots.
Furthermore, be sure to knock down any snow accumulation to prevent physical structural damage. It’s not uncommon to wrap your arborvitae during periods of extreme weather. A basic burlap can do the trick.
Hopefully, now you have a better understanding of your arborvitae’s seasonal needs, and if you find that your tree requires assistance, please contact Mr. Tree to schedule your service.