The water oak is an integral part of the ecosystem in its native range that stretches from New Jersey to Florida and west to Texas. It also graces landscapes across its hardiness zones because of its attractiveness, extreme ease of care, and ability to seemingly grow right before your eyes. The water oak will grow an astonishingly fast 24 inches a year, making it a great asset to landscapes in need of fast-growing specimen or shade trees. Unfortunately, this same speedy growth rate makes the wood fragile and prone to insects and disease. The other downside, for such a large stately tree, is relatively short-lived compared to other oaks. You will need to weigh the positives against the negatives when considering adding Quercus nigra to your landscape.
|Common Name||Water Oak|
|Botanical Name||Quercus nigra|
|Plant Type||Deciduous Tree|
|Mature Size||70- 80 ft. tall - 40-60 ft. wide|
|Sun Exposure||Full Sun|
|Soil Type||Sandy Loams, well-drained soil|
|Bloom Time||Early Spring|
|Hardiness Zones||USDA 4a-9a|
|Native Area||Eastern to Midwest North America|
Water Oak Care
Caring for a water oak is knowing that it is unlike other oaks. Water oak wood does not have the strength for which other oak species are known. Because of this, preventative pruning must be done early, within the first three years of planting with regular maintenance intervals, to ensure that property damage is kept to a minimum. Of course, damage can be prevented with good planning and following the right tree right place mantra. The amazing thing about the water oak is that this same weak wood is that quality makes it such an asset to wildlife. The tendency for water oak to have hollow branches and decaying wood allows it to be a valuable habitat for so many animals. Again, it is all about weighing your options and knowing if the water oak is the best choice for your landscape design.
Like most oaks, the water oak demands full sun and will not thrive in any other conditions. Your tree will be happiest if planted in a place that gets at least six hours of direct sunlight a day. Water oak will not tolerate shady conditions at all.
Usually found in lowland floodplains and along rivers and streams, the water oak prefers soils mimic its native conditions. It grows best in organically rich, humusy soils that are moist to wet soils. Water oaks are somewhat adaptable soil-wise but prefer soils that tend to be on the acidic side.
For a tree that is native to areas inundated with water, Quercus nigra is surprisingly drought tolerant. Its watering needs are mostly shown while young and trying to establish itself. Like most trees, it is recommended that you water the water oak for the first two seasons until it is established. You can water your oak using the normal formula of 2-3 gallons inch of trunk diameter measured by caliper at trunk height. After your tree is established, you can leave the irrigation to mother nature.
Temperature and Humidity
Water oaks are not especially cold-hardy and prefer warmer southern weather. Down south, the tree can be semi-evergreen, but it will be strictly deciduous in places like New Jersey. The water oak is one tree that you should closely follow the USDA zone recommendations due to limb breakage and potential for property damage from adverse weather.
Before providing any fertilizer to your water oak, it is advised that you test your soil. This species is not necessarily a tree that needs supplemental fertilizer, and any issues that your tree may be having are most likely not due to soil deficiencies. If your soil is found lacking, you will know what it's lacking and supply the right nutrients to compensate for the deficiency.
Types of Water Oak
Like most oaks, interbreeding comes through hybridization, which means there are few cultivars created in the nursery trade and more varieties and hybrids created in nature. Here are two well-known exceptions to that rule bred in the nursery trade are mainly for their glorious autumn color:
- Quercus nigra × coccinea 'Fire Water' - will grow into a small tree with fiery orange and red autumn color once established.
- Quercus nigra 'Thierry' -medium size and conical shape, with a wide rounded crown and alternate and simple leaves that turn yellow in the fall.
There will be two main types of pruning you will need to do to your water oak. The first will occur over the first five years after it has been planted. This pruning is the structural pruning to establish a single dominant leader. Many water oaks in the wild establish multiple leaders, causing the tree to develop an almost shrubby weeping habit. The second type of pruning will be preventative pruning to remove dead and damaged limbs and branches. You will need to do this ongoing throughout the tree's lifespan and will need to transition to a professional certified arborist as the tree becomes too large for you to manage. You may think the cost is prohibitive, but it is considerably cheaper compared to the cost of damage or loss of property or injury.
There are two ways to propagate water oaks, hardwood cuttings and planting seed or acorn. Water oaks drop an abundant amount of acorns, so this is the easiest way to go with this species and the one that this article will be cover.
- Collect acorns in early autumn and remove the caps.
- Put the capless acorns that you've collected in a container full of water.
- Stratify the acorns in the refrigerator in a plastic bag filled with a moist mix of peat, vermiculite, and sand for one and a half to three months.
- Plant each acorn in a pot. Germination may have begun in the bag. Plant just below the surface with the root downward and water thoroughly.
- Transplant into a larger pot and place this pot outside to allow it to harden. Doing this will acclimate it to outdoor conditions.
- Plant your hardened off oak seedling in its permanent place and allow it to grow with a tree cage around it to protect it from animals.
Common Pests and Plant Disease
Though a long list of pests can plague it, the damage done by the insects is not serious, and you should seriously consider any control methods before they are attempted. Water oaks are host to numerous moth and butterfly species which are beneficial to local ecosystems, and pesticide use often does not discriminate.
Likewise, diseases that affect the water oak, other than for oak wilt, no diseases are normally serious. Oak wilt can be treated with tree fungus treatment injections, as long as it is caught early enough. For advanced cases, nothing can be done, and the tree will die. When a tree is diagnosed, you should apply a fungus treatment to the surrounding trees to prevent the spread of this disease and remove the infected tree and wood. A certified pesticide applicator should handle these injections and applications.