How to Grow and Care for Swamp White Oak

Swamp White Oak Care

Here are the main care requirements for growing a swamp white oak:

• Prefers full sun, although can tolerate partial sun.
• Grows best in clay, loam, sand, or a well-draining moist soil.
• Plant in neutral or acidic soil.
• Tolerates hot and subzero temperatures.
• Supplement with fertilizer or organic compost in poor soil conditions.

Light

Swamp white oak is best grown in full sun, but it tolerates partial sun.

Soil

Provided the soil is acidic to neutral (pH range 5.0 to 7.4) and has a high mineral content, the tree can grow in a wide range of soils, from clay to loam or sand.

The tree grows in water-saturated soil in its natural habitat, hence its name. However, this is not a prerequisite. Swamp white oak also grows well in well-drained soil or soil with occasional flooding and saturation.

The tree’s ability to survive in water-saturated soil, which means low oxygen levels, makes it also suitable for locations, such as urban areas, with heavily compacted soil, as long as the acidity requirement is met.

Water

While swamp oak prefers consistent moisture, it can withstand dry periods.

On the other hand, a newly planted tree should be watered regularly—as much as weekly—in the absence of rain for the first two summers until it is well established.

Temperature and Humidity

As a native tree to a wide climate range, swamp white oak is tolerant of hot weather as well as subzero winters.

Fertilizer

Besides amending the soil with plenty of organic matter before planting a new tree, the best regular fertilization you can give an established oak tree is to allow fallen leaves to remain on the ground in the autumn, adding nutrients to the soil when they decompose.

If a soil test indicates poor soil, add a slow-release fertilizer in early spring so it’s available to the tree as the weather warms up and the oak starts growing in spurts. The recommended N-P-K ratio for oaks is 12-4-8 (12% nitrogen, 4% phosphorus, and 8% potassium). Do not fertilize late in the growing season, as it will lead to extra foliage growth and make the tree more susceptible to winter injury.

Types of Swamp White Oak

Swamp white oak is a member of the white oak group, including bur oak and white oak (swamp white oak and white oak are two different species).

How to Identify a Swamp White Oak

Swamp white oak is a rugged tree native to much of the United States, from Maine to Florida and westward to Minnesota and Texas. To identify a swamp white oak from other oaks, it has long 5 to 7-inch leaves with rounded, shallow lobes. It has dark green leaves with gray to white downy undersides. The twigs are green and lustrous, becoming light orange colored or brown by the first winter. A distinguishing feature is their acorn fruits that grow on thin stalks up to four inches long.

Swamp White Oak Cultivars

• ‘American Dream’: This swamp white oak cultivar has a broadly pyramidal shape and dense foliage. Its leaves are deep green, thick, and glossy, changing to yellow-brown in the fall. The cultivar has good resistance to anthracnose and powdery mildew.
• Beacon’s ‘Bonnie and Mike’: This swamp white oak cultivar has a narrow columnar shape. Its branches grow upright instead of spreading, which makes it suitable for urban settings. The foliage turns yellow in the fall.

Pruning

Swamp white oak does not naturally form a leader, and its branches tend to droop as the tree grows. Prune the young tree to a central leader and the lower limbs that start low. Prune for clearance of vehicle or pedestrian traffic.

Propagating Swamp White Oak

It is possible to grow swamp white oak from acorns but getting the timing right can be challenging. You need to wait for a tree to drop its acorns naturally, and then collect them promptly, as they dry out within three to four days after they drop and become unviable. In light of this, it is recommended to purchase a seedling or young tree from a nursery. Swamp white oaks in containers can be planted any time between spring and fall.

How to Grow Swamp White Oak From Seeds

Growing a swamp white oak from an acorn can take several years before the seedling is large enough to be transplanted into the ground. The choice of acorn is essential. Do not use any acorns that are cracked or have holes. Soak the acorns in water for 24 hours. Discard floating acorns, which are nonviable. Here’s how to grow from seed:

1. Fill a 1-gallon planting container with a drain hole with the same soil as the location where you intend to plant the tree. Enrich the soil with organic matter or compost.
2. Place two to three soaked viable acorns in the container, laying them on their sides. Cover with 1 to 2 inches of soil. Water regularly and deeply.
3. The acorns should start to sprout in about one month. Keep only the strongest seedling.

Overwintering

These very cold-hardy trees can tolerate freezing temperatures in their usual growing zones. Protect young saplings still in containers or newly planted outdoors with a layer of mulch or straw over the root zone.

Common Pests & Plant Diseases

Swamp white oak is susceptible to anthracnose, canker, powdery mildew, shoestring root rot, and oak wilt. The tree can also get leaf spot, which is common to appear on oaks late in the season and is merely an aesthetic issue that won’t kill the tree. Leaf blister, a fungal disease that looks like little bumps on the leaves, can defoliate a tree.

Common Problems With Swamp White Oak

Swamp white oak is a low-maintenance tree, but it needs to be given plenty of room to grow freely.

Yellowing Leaves

When a swamp white oak shows signs of chlorosis, the underlying cause is alkaline soil, which makes nutrients unavailable to the tree. This can occur suddenly even to a mature tree after a new structure has been erected nearby. The likely cause is nearby concrete or limestone, which increases the pH of the soil and makes it alkaline.

To avoid this condition, do not plant a swamp white oak near building structures. If unavoidable, add organic materials to the soil to reduce soil pH: peat moss, rotted manure, or rotted leaf compost, which the tree produces every fall.