Naturally found in the rich, moist soils of cold swamps, dahoon is said to have been used for cleansing by Native Americans; both as soap and to purge the body. Dahoon attracts various mammals, such as squirrels. When cultivated, this evergreen can be used as a screen or hedge.
I. Appearance and Characteristics
Ilex cassine is a holly native to the southeastern coast of North America, in the United States from Virginia to southeast Texas, in Mexico in Veracruz, and in the Caribbean on the Bahamas, Cuba, and Puerto Rico. It is commonly known as dahoon holly or cassena, the latter derived from the Timucua name for I. vomitoria.
It is a large shrub or small tree growing to 10–13 m tall. The leaves are evergreen, 6–15 cm long and 2–4 cm broad, glossy dark green, entire or with a few small spines near the apex of the leaf. The flowers are white, with a four-lobed corolla. The fruit is a red drupe, 5–6 mm in diameter, containing four seeds.
As with other hollies, it is dioecious with separate male and female plants. Only the females have berries, and a male pollenizer must be within range for bees to pollinate them.
II. How to Grow and Care
Sunlight
Dahoon holly thrives in full sun but can be entirely adequate in a partial shade location where it receives two to six hours of direct sunlight daily.
Temperature and Humidity
While the Dahoon Holly thrives in the USDA zones 7a to 11, it does best in the hardiness zones 8 and 9. When grown in zone 7, you may need to provide some winter protection. You can give some protection using burlap to prevent winter burn on the leaves.
The younger specimens have thin bark and can benefit from protection using the cloth as it prevents animals from gnawing the bark. The plants can tolerate full sun with high humidity levels in coastal regions 10 and 11. But the growth might be a bit subdued as it is mildly salt tolerant.
Watering
In its native habitat, dahoon holly is found in boggy areas where moisture is a constant presence, so it will grow best if you can mimic those cultural conditions. After planting, cover the soil with 2 inches of mulch to retain moisture. Water the roots thoroughly during the first year. Be sure to water more often during periods of drought. Without proper watering, the roots will reach for any source of moisture and become stressed.
Soil
Dahoon holly prefers consistently moist soil, as befits a plant that is naturally found in the swamps, bogs, and damp woodlands of the Gulf Coast from Florida to Texas. It will grow in clay, loam, or sandy soils, but if the soil is naturally dry, the roots require regular watering.
Fertilizing
Dahoon holly doesn’t demand regular feeding, but if your soil is alkaline, an annual dose of an acidifying fertilizer, according to product instructions, may help prevent chlorosis (leaf yellowing).
Pruning
established dahoon holly. However, like most hollies, it willingly accepts hard pruning to shape it. Pruning helps the tree grow strong and structured. This holly is also a good tree often used for bonsai practice.
Berry-producing evergreen hollies like dahoon are best pruned in the dormant period of late winter so that you don’t remove the attractive berries that form during the summer growing season. They can also be pruned in the summer immediately after flowering, but this will remove the current season’s berries; if you prune at this time, be prepared for a winter without the bright red berries.
How you prune will depend on the effect you desire, but in general, it’s wise to begin by removing any crossing or rubbing branches. If you want a more traditional tree-like effect, competing leaders can be pruned away when the plant is young to favor a central leader to serve as a trunk. If using the plant in a hedge, conclude the pruning session by trimming back the tips of the branches to produce the desired outline. Avoid pruning the canopy if possible; it has a rather open habit with twisted, small-diameter branches coming from main stems to create a drooping effect that makes an effective privacy screen.
Propagation
With full sun and proper watering, your Ilex cassine thrives in consistently moist soil and develops those beautiful dark green leaves.
Still, the exciting thing is that female plants do not need a male pollinator to produce those berries but only need smaller animals and bees to help pollinate.
The fruit is an excellent food source for animals, and they spread the seeds. But you can propagate your tree to gift to another person.
Here are two ways you can do this:
Stem Cuttings
- With sharp, sterilized pruners, cut segments from the tips of new branches in mid-summer. These segments can be up to five inches long. Then strip away the bottom leaves and leave some top leaves.
- Take the cut end, dip it in rooting hormone, and place it in a pot with perlite and sand. Moisten the soil and put it in a plastic bag.
- Leave your containers in a warm location in bright indirect light and inspect the water weekly and open the container daily for air ventilation for about an hour.
- After about six weeks, a root system should develop, and you remove the bag and leave it standing in a sunny location in a sunny window. Then, you can pot your cutting outdoors in a warm winter area.
- Wait a few months to transplant your young plant to a bigger pot and grow in a sunny location throughout the winter to plant outdoors in spring.
Growing from Seed
Growing your plant from seed is not easy, as it can take up to three years of dormancy. The other concern is that you may have male or female plants and not both. So, you will need a male and female tree to develop seeds.
Still, if you want to try it, we recommend peeling off the skin of the ripe fruit during fall. Then break them apart to get entry to the seed. Next, rinse them in cold water and plant them in a tray with some starter potting mix.
Cover the trays with plastic and leave them in a protected area outdoors during winter. It will take loads of patience, up to three years, to repeat the process before it germinates.
Potting and Repotting
Though container culture is not common, dahoon holly is by nature a slender and fairly well-behaved plant that readily accepts pruning. It makes a good container tree for the patio or deck when planted in a large, heavy, well-draining container filled with a good moisture-retentive potting mix. These plants do not much care for repotting, however, so it’s best to choose a large pot right from the start.
Dahoon holly is also used for bonsai practice. New shoots are constantly clipped off and directed with wires, and the plants undergo frequent root pruning. The plant is carefully removed from its pot to have the roots trimmed.
Overwintering
Dahoon holly generally does not require protection against the winter cold. However, if you are in zone 7 you may find that tenting the shrub with burlap during the coldest periods will prevent desiccation and winter burn to the leaves.
These trees have relatively thin bark, so young specimens may benefit from shielding the trunk with hardware cloth to prevent rabbits and other creatures from gnawing the bark. Shielding the trunks can also prevent damage from mowers and other mechanical equipment. This protection isn’t needed for older trees.
In areas with dry winters, make sure to thickly mulch the ground to preserve soil moisture.
Pests and Diseases
Common Pests and Plant Diseases
Aside from pruning, dahoon holly is a virtually maintenance-free plant that rarely suffers from pests and plant diseases.
Insect pests also generally leave dahoon holly alone though the tree is quite susceptible to two-lined spittlebugs,3 which leave frothy trails of excretion as they feed on leaves. Seriously infested trees may drop leaves. Spittlebugs are fairly easily treated by blasting the leaves with water to dislodge them. Good cleanup beneath the tree will remove eggs and prevent a new infestation.
Occasionally, mites, leaf miners, and scale insects may feed on leaves and stems but the damage is rarely serious enough to require treatment. Dry conditions are more likely to encourage these pests.
Fungal diseases that are common to many other hollies do not seem to affect this tree. You may see swelling (twig gall) on the foliage or twigs if the plant is experiencing a fungus infection, but these growths tend to naturally die back and usually don’t require treatment.
Common Problems
This plant is largely free of the complaints common to other species of holly. Regular watering makes for a healthy plant that resists most problems. However, stay on the lookout for the following issues.
Yellowing Leaves
Like many acid-loving plants, a holly that grows in soil that is too alkaline may develop chlorosis, a condition where the leaves become yellowed, while the veins show as dark green. The solution here is to lower the soil pH, either through an iron-boosting amendment or by fertilizing the plant with an acidifying fertilizer, such as one formulated for azaleas.
Shriveled Brown Leaf Tips
On occasion, the leaves of dahoon holly may develop scorch due to rapid temperature fluctuations in late winter. This doesn’t produce any long-term harm; the tree easily recovers.
