Light
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.
Soil
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.
Water
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.
Fertilizer
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.
Pruning
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.
Propagation
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.
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.
