The American mountain ash tree, also known as Sorbus americana, is a lovely ornamental tree native to eastern North America. With its graceful form, showy white flowers, vibrant red berries, and brilliant fall color, it’s no wonder American mountain ash is a favorite for landscapes. If you’d like to add one of these beauties to your own yard, proper planting depth is crucial for getting your tree off to a good start. In this complete guide, we’ll cover everything you need to know about how deep to plant your American mountain ash for optimal growth and health.
Overview of American Mountain Ash
Before jumping into planting depth, let’s briefly go over some background on American mountain ash trees. Here are some quick facts:
- Deciduous small tree, growing 15-35 feet tall at maturity
- Native range extends from Maine to Georgia in cool, moist forest areas
- Clusters of white spring blossoms attract pollinators
- Showy red berry clusters in summer and fall feed wildlife
- Prefers acidic, well-drained soil
- Grows best in full sun to partial shade
- Cold hardy in USDA zones 2-6
With multi-season interest, modest size, and adaptability, it’s easy to see why American mountain ash makes a great addition to many landscapes. Now let’s get into the ideal planting techniques for this wonderful native tree.
Recommended Planting Depth
When planting your American mountain ash tree proper depth is important to consider. Here are some key tips
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Avoid planting too deep – This is one of the most common mistakes when planting trees. Planting too deep can cause decline, poor growth, and even death by suffocating the roots.
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Plant at same depth as grown in nursery – Check for indicators of original growing depth like a soil line on the trunk. Plant your mountain ash at the same soil level it was originally grown at in the nursery.
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Root collar should be partially exposed – The root collar, where the roots meet the base of the trunk, should be right at or slightly above soil level when planting American mountain ash trees.
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Plant high rather than planting deep – If unsure between two depths, always opt to plant a little too high rather than too deep. It’s easier to add soil later than try to excavate a planted tree.
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Mound soil if needed – Mounding a bit of soil over the root system can help stabilize the tree after planting. But be sure not to mound soil up onto the trunk.
Proper planting depth is all about getting the root system at the right level in the soil. Follow these guidelines when planting your American mountain ash tree to prevent problems down the road.
Step-By-Step Planting Instructions
Now let’s walk through the complete process for planting American mountain ash trees at the proper depth:
Choose an appropriate planting spot
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Select a location with full sun to partial shade – mountain ash needs at least 4 hours of direct sun per day.
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Pick a site with well-draining, slightly acidic soil enriched with organic matter. Avoid wet, soggy sites.
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Give it plenty of room – allow at least 15-20 feet between trees.
Dig a wide planting hole
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Dig a hole 2-3 times wider than the root ball but no deeper than the height of the root mass.
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Score the sides of the hole with a shovel or pruning saw to rough up the edges. This encourages root growth outward into the surrounding soil.
Set the tree at proper depth
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Check for indicators of original planting depth and match that level in the new hole. Root collar should be partly visible.
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If repotting from a container, gently loosen any circling roots before placing in the hole.
Backfill with native soil
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Refill the hole with the soil you removed, blending in compost or peat moss. Break up large clumps.
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Water thoroughly while backfilling to eliminate air pockets.
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Avoid amendments like gravel or sand that can leave voids in the soil.
Build a soil mound if needed
- If the root collar sits a little low, mound native soil over the roots to stabilize, but don’t cover the trunk.
Water and mulch well
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Water thoroughly immediately after planting and as needed the first season.
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Top dress the soil with 2-4 inches of organic mulch to conserve moisture and suppress weeds. Avoid piling mulch onto the trunk.
First Year Mountain Ash Care
Caring properly for your American mountain ash tree in the first year after planting is crucial. Here are some tips:
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Water 1-2 times per week, aiming for 1 inch total weekly rainfall/irrigation.
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Apply a balanced, slow-release fertilizer early in the growing season.
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Prune only damaged or crossing branches – avoid heavy pruning the first year.
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Check soil moisture levels in the root zone regularly.
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Surround the base with a protective wire cage if rabbits or deer are an issue.
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Weed and reapply fresh mulch as needed around the root zone.
With the proper planting depth and some attentive care in the first year, you’ll set your American mountain ash tree up for many years of beauty and enjoyment. Just remember to avoid the common mistake of planting too deep, and be sure to mound soil over the base if needed to get the root collar at the perfect level. With this complete guide, you’ll be equipped to get your mountain ash planted properly the first time.
American Mountain Ash Fact Sheet
Mountain ash is a tree species that is native to eastern North America. It can be found from Canada south to the mountains of Georgia and can be found as far
west as Minnesota. Mountain ash prefers moist soil and full sunlight, growing along forest edges, roadsides and swamp areas. Height will vary based on conditions, but generally ranges from 10-30 ft.
The ash serves multiple roles within the ecosystem. In addition to providing shelter, it is a source of food for a variety of forest organisms. Moose and white-tailed deer feed on the leaves, twigs and branches. Smaller mammals and birds consume the red berries.
Humans monitor this species for both its function in the ecosystem and its potential effect on human health as an allergen.
Leaves: Leaflets with serrated edges grow in the form of compound leaves with an alternate pattern along the trunk. They are dark green in color, narrow and 2-2 ½ in long.
Flowers: Small, white flowers grow in clusters that are 3-5 in across. Flowering occurs between May and July.
Fruit: Mountain ash produces small red berries that ripen in August and remain on the tree through early winter.
Bark: On younger trees, the bark is gray and smooth. With age, the bark becomes scaly in appearance.
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FAQ
Where is the best place to plant mountain ash?
Do ash trees have deep roots?
What kind of soil does American mountain ash like?
How fast does American mountain ash grow?
What kind of soil do mountain ash trees need?
About soil condition, the mountain ash tree needs a well-drained soil, and it’s best in acidic to neutral soil. It’s tolerant of poor soils, including clay, but it doesn’t do well in wet or waterlogged soils. Not too different with other trees, mountain ash trees need sunlight to grow.
How to plant a mountain ash tree?
For mountain ash tree, first step is to find a good location. You need to choose an area that gets full sun and has well-drained soil. If you are planting more than one tree, space them at least 15 feet apart. The second step is to dig a hole that is twice as wide and just as deep as the trees root ball.
What are the roots of American mountain ash?
The roots of the American Mountain Ash tree are essential for anchoring the tree in the soil, absorbing water and nutrients, and providing structural support. Like most trees, the root system of the American Mountain Ash consists of two main types of roots: the shallow fibrous roots and the deep taproot.
When should I plant mountain ash trees?
Plant or relocate mountain ash trees in early spring with full to partial sun and moist soil. The best time to plant or relocate mountain ash trees is in early spring while they are still dormant. Before planting your seedlings or saplings, be sure that the location has full to partial sun and moist, acidic soil.