How to Grow and Care for a Red Oak Tree

Red Oak Care

Red oak won’t require much care once it becomes established other than some light preventive maintenance and watching out for rare insect or disease problems. It is a carefree tree as long as it stays healthy and is given a good start.

Here are the main care requirements for growing a red oak:

• Plant it in a location that ideally gets full sun and accommodates a future tree up to 100 feet tall and 60 feet wide. Remove all grass within a three-foot diameter from the tree, so it doesn’t compete with the tree for water.
• Make sure the soil is on the acidic side.
• Water twice a week for the first year and once a week in the second year. Afterward, unless it’s unseasonably dry, no supplemental water is needed.
• Mulch over the entire rooting area with 2 to 4 inches of bark mulch. Keep the mulch at least three inches from the stemtrunk.
• Do not use soil amendments or fertilizer in the first year.
• Prune mature trees annually to remove dead, diseased, or broken wood.

Light

Place your red oak in a place that will receive plenty of sunlight. Oaks need full sun to part sun to thrive; giving anything less will cause some issues. Even if you plant it near another tree, it will like some room to allow its canopy to get sunlight.

Soil

Though not incredibly picky about its soil, if you want your oak at its happiest, you will want to give it sandy, well-draining soil that is somewhat rich and acidic. Test your soil’s pH before planting to check if you need to adjust the pH.

Never layer more than an inch of soil over its roots. All roots need room, but this is especially important for oaks.

Water

While your oak establishes its roots and matures for the first few years, you should water it weekly. It will take a good amount of water, especially during dry periods; 10 gallons per inch of trunk diameter is a good standard. Once your oak is established, don’t worry about watering it any further; Mother Nature should take care of it just fine.

Temperature and Humidity

Red oaks are frost-resistant and handle the cold, wet winters and hot, humid summers of the Northeast and Mid-Atlantic. As the climate changes and warms, their zones are shifting northward. They are presently listed as hardy in USDA Zone 4-8.

Fertilizer

Your oak should not need any supplemental fertilizer. In the rare case that your oak seems lagging, you should test the soil and check for soil deficiencies. To correct any nutrient deficiencies, fertilize with the appropriate NPK formulation to compensate for the deficient nutrient with a slow-release fertilizer at the tree’s drip line.

Types of Red Oak Trees

Red oak (Quercus rubra) is part of the red oak group. These oaks have points on the leaf lobes and their acorns mature in two growing seasons (unlike white oaks).

Members of the red oak group include:

• Willow oak (Quercus phellos): Native to the Atlantic, Gulf Plains, and the Mississippi Valley, this oak is also distributed across the South. It is a shade or street tree with willow-shaped leaves that can live for over 100 years and grows over 100 feet tall.
• Scarlet oak (Quercus coccinea): Native to the eastern and central parts of the United States, it is considered a versatile tree because it thrives in less-than-ideal acidic, dry soil, as well as tolerating alkaline soil. It is fast-growing to a height of 50 to 70 feet tall and 40 to 50 feet spread.
• Black oak (Quercus velutina): The tree has a distinctive dark blackish or brownish-gray bark. It grows in the eastern United States and does not tolerate shade or growing on slopes.
• Pin oak (Quercus palustris): Also called swamp Spanish oak, it grows in the Central and Eastern United States. It has a pyramid-shaped crown and hanging branches at its base and grows about 50 to 70 feet tall.

Pruning

Prune in the dormant season to avoid the spread of oak wilt disease. Remove dead, diseased, or damaged branches using sterilized pruning tools. Dead branches are brittle. Diseased and damaged branches have blemishes, wounds, discoloration, or scars.

Remove old and weak wood to provide air circulation and light, helping the tree fight disease and pest infestations. You can prune away up to 13 of the old wood in a season. Sterilize your tools in between cuts. Remove limbs that crisscross other limbs and cut off shoots that grow vertically straight up or downward. Prune any branches that grow at less than a 30-degree angle to the tree trunk.

Propagating a Red Oak

Growing an oak from acorns is a common method of propagation.

1. 1. In the fall, collect the second acorn batch that drops (the first batch is often poor quality). Collect the acorns promptly once the tree drops them because acorns dry out quickly and become inviable. You should have at least twice as many acorns as the number of plants you want in case some acorns don’t germinate.
   2. Remove the caps of the acorns; these are protective covers of the seed material. Unless you tear into the seed, you will not be damaging the seed by removing the cap.
   3. Perform a float test. Place your acorns in a large container of water and set them aside for five minutes or so. If any acorns are floating, discard them, as these are not viable seed material.
   4. Plant the acorns in pots deep enough for root growth. 2.5 x. 2.5 x 3.5-inch pots are ideal. Fill the pots with potting mix. Place two acorns sideways in each pot, at a depth about three times the width of the acorn, or about one inch. Water them well until water runs out of the drainage holes.
   5. Keep the soil moist until the onset of winter weather. Leave the pots outdoors all winter but cover the pots with a screen or hardware cloth to protect them from critters.
   6. Once the seedlings emerge in the spring, remove the protection. If both acorns in a pot germinate, cut off the weaker of the two seedlings.
   7. Let the seedling grow to a height of 12 to 18 inches before transplanting it in the landscape. Keep the soil moist at all times.

Overwintering

Red oaks are cold-hardy trees that tolerate freezing temperatures in their growing zones. Newly planted trees benefit from a layer of mulch or straw over the roots to insulate them against the cold.

Common Pests & Plant Diseases

Oaks are susceptible to oak leaf blister, a fungal infection that resembles water blisters on the leaves. It often causes a midsummer leaf drop. If you otherwise keep the tree healthy and on a regular water schedule, it should be able to fight the infection independently. A young tree can be treated with fungicide.

Bacterial leaf scorch is another common occurrence among red oak trees. Summer droughts are often the cause. It affects water uptake, eventually leading to decline, leaf yellowing and browning, leaf drop, dieback, and death. Insects spread this bacteria. It’s best to remove the infected tree to prevent the spread of the deadly bacteria.

Red oak is susceptible to fungus cankers, which look like white and brown growths on the tree’s bark. Remove the branches that develop these growths when you notice them using sterilized pruning tools.

Oak wilt is a certain death sentence for the tree.

Common pests that like these trees are leafhoppers or caterpillars. Birds will feed on those insects to control them.

Common Problems With Red Oak Trees

This relatively easy-care tree has few major problems, except those specific to oak trees.

Browning of Top Leaves

Oak wilt is a severe fungal disease causing the browning of the tree’s crown, eventually leading to other parts of the tree, then certain death. Beetles spread the disease, usually spreading the fungus in the tree’s vascular system through open cuts or wounds (usually from pruning). Recovery is not possible; removal is recommended. This fungus has gradually spread to more than 20 states.

Pale or Unseasonal Yellowing of Leaves

Northern red oaks are susceptible to chlorosis, which causes deep green leaves to become pale or yellow. This condition is often caused when the soil pH is 7 to 7.5, which is too alkaline for the tree. To correct this, increase the soil acidity by adding sulfur. Make sure to do a soil test to determine the required amount and frequency of applications.

Powdery White Leaves

Leaves with a powdery white appearance likely have powdery mildew, a fungal infection. Leaves may also look malformed, drop, or shrivel up. If a young tree is heavily infected, treat it with a fungicide at least 24 hours before rain or watering. Mature trees do not need treatment.