How to Care for a Hibiscus Tree
If you want your home’s exterior to have the look of the tropics with a beautiful, blooming flowered tree, the deciduous hibiscus tree will provide you with a stunning addition to your yard or patio. The blooms can reach 8 inches in diameter and colors range from pink, yellow, and peach to dark red. They are very attractive to hummingbirds and butterflies alike. Although only suited for warm climates, the hibiscus tree with its thick, green, leafy fullness can reach heights up to 12 feet and widen to about 6 feet, creating a lush looking landscape. But, as with other landscaping plants, it will require care.
TIP: Our expert gardening advisor, Rachel Klein adds, "Grown singly, hibiscus are beautiful. However, they also make a stunning hedge plant in frost-free climates."
Step 1 - Find the Right Placement
The tropical hibiscus is hardy in UDSA zones 9 through 11, meaning that in these zones you can plant your hibiscus outside. It flowers best in temperatures from 60 to 90 degrees F, and cannot tolerate temperatures below 32 degrees. If the temperature drops below 50 degrees routinely, like at night, the hibiscus may survive but will cease growing or blooming. The tree should be planted in full sun in well draining soil. Space hibiscus 3 to 6 feet apart.
TIP: Rachel suggests, "If you like the look of an outdoor planted hibiscus but live in too cool a climate, consider a hardy hibiscus. The hardy hibiscus is much more tolerant of cold. Also called the Rose of Sharon tree, it flourishes in USDA zones 5 through 9. Another hibiscus look-alike, the rose mallow, grows 4 to 6 feet tall and thrives in zones 5 through 10."
To plant, dig a hole as deep as the root ball and 2 to 3 times wider. If you have poor soil, amend it with compost, vermiculite, or leaf mold. If your soil is not well-draining add a few handfuls of sand and peat moss to the hole. Lower the root ball gently into the hole and fill half way with your soil mixture. Water the plant thoroughly to settle the soil, and then fill in with the remaining dirt, tamping down firmly.
Step 2 – Water Carefully
Hibiscus trees require careful watering, so the roots do not become saturated with water and develop root rot. Careful watering can also prevent the growth of mildew or fungus. Your tree will better develop its rich, green, and thick foliage if in warm weather you keep its roots moist but not over-watered. The right degree of moisture will also help the plant promote continuous blooms. [Water your hibiscus 1 or 2 times a week for the first year after planting, making sure that the tree is getting at least 1 inch of water per week. Keeping your hibiscus well watered is most important while the tree is in bloom.] During cooler months of the year, be careful to water the plant only when it becomes dry. Yellowing leaves can be a sign of under-watering.
Step 3 – Fertilize
Yellowing or fading of the leaves can also indicate that your hibiscus tree is in need of fertilizer. To maintain the dark, glossy, green color of a healthy hibiscus tree, use a high nitrogen fertilizer when the leaves begin to fade. Apply fertilizer at half strength, rather than full strength. In the spring, apply a slow release type fertilizer, so your tree will develop new growth. Use a balanced preparation such as 10-10-10 or 20-20-20. Avoid allowing the fertilizer to come into direct contact with the tree and water well after application.
Step 4 – Prune
As with other trees, pruning your hibiscus tree will help it develop to a fuller shape. Pruning produces an abundance of hormones in the tree. These hormones will, in turn, activate buds that have become dormant through the cooler months. Spring is good time to prune your outdoor trees.
If you are growing your hibiscus in a pot to bring indoors during the winter, it is a good idea to keep your hibiscus small for a more convenient indoor size. You would be surprised how much one hibiscus can grow over the summer, so in the fall before bringing it indoors you should prune the tree back. Hibiscus can take very extreme pruning, and can flourish after being reduced by as much as 50 percent. Just be careful to leave some new growth and old leaves on the bush after pruning. Because the light will be lower inside, the hibiscus will grow back slowly and should not need to be pruned again all winter.
Step 5 - Remove Tips and Branches
When you prune your tree, be sure to remove dead or old branches using pruning shears. When you first prune, you may feel you have compromised the beauty or attractive shape of your tree. But don’t be concerned. Your tree will begin to fill out even more once it has been pruned. When you prune it, be sure to remove the tips of the branches. Just pinch off these tips 1/4 inch above a new leaf bud. When they have been removed, this allows new tips to begin developing deeper in the stem of the tree.
Step 6 - Encourage Blossom Development
While it is true that pruning will initially slow the development of blossoms on your tree, it will be only for a few months. And, it will only be in the area you have pruned. Once the tree does begin to blossom, you can expect that the blossoms will be larger and healthier.
Deadhead your hibiscus regularly. The stunning blooms will only last 2 days or so and should be plucked from the tree as they begin to fade. Fading blooms will appear shriveled, drooping, and partially closed. Keeping dying blooms off your tree will promote more perfuse blooming. At the same time, pluck off any damaged or yellowing leaves.
TIP: Rachel advises, "The hibiscus is typically very disease and pest resistant. However, keep a wary eye for stunted growth, discolored blooms, and leaf and bud drop, the signs of a infestation or disease. Prune off affected limbs immediately with sharp clean pruning shears. Destroy the pruned material, do not compost it. Minor insect infestations can usually be dealt with by spraying thoroughly with a strong hose stream. Organic insecticidal soap also works well."