Oleanders will only tolerate temperatures as low as 15 degrees Fahrenheit (-9. 4 degrees Celsius). At that point, however, the foliage will be damaged. [1] X Research source Even if the top of a plant becomes damaged, it can still grow back as long as the roots remained unharmed. If you live in a cooler climate, you will need to plant oleanders in a heated greenhouse or in movable containers. Each container must be at least two to three times as wide and deep as the root ball of the bush you plan on keeping. Keep the container outside during the warmer weather and take it inside during the winter. [2] X Research source
Typically speaking, the ideal time to plant an oleander is August or September, just after the blooming period ends. If you plant the bush any later than that, the blooming period might be shortened. Oleanders planted in spring may not produce many blossoms during its first year, but the foliage should remain healthy and new blooms should appear during the following growth season.
When grown in partial shade, oleanders tend to take on a lanky, open shape instead of a full, bushy one. Note that in especially hot, dry climates, a location that receives partial shade may actually be better than one that receives full sun. Also note that oleander bushes are good to use as “walls” against wind and can protect more sensitive plants, but damage caused during severe winds can ruin open blossoms and closed buds for the season.
The best soil for oleanders will be well-drained. These plants are quite adaptable, though, and can usually survive well enough in both dry soils and marshy soils. Additionally, soil content does not often make much difference. Balanced, nutritional soils are always best, but oleanders can still survive well in soils with high pH readings, high salt content, and similar problems. While not necessary, you could also add peat moss to sandy soils if you want to increase the soil’s ability to hold water.
Avoid plants labeled as “double white,” “single red,” and so on. Instead, opt for plants that specifically name which variety is being offered. Inspect the plant before making your purchase. Make sure that there are no aphids, mealy bugs, or other insects. Gravitate toward plants that are not “pot bound. " The root systems should not be overgrown and peeking out of the growing media.
Burying the plant too deeply can cause the base of its main stem to remain underground, which can cause moisture damage. Failing too make the hole wide enough can make it difficult to fill the hole in with enough soil.
If using a balled or burlapped plant, carefully cut any string or material surrounding the root before placing it in the hole. Avoid damaging the root as you free the football or transplant the bush.
Backfill the soil into the hole gently. Do not pack it into the hole with your hands since doing so could cause damage to the root system.
Wait a few moments after applying the water. You need to let it remove all the air pockets and thoroughly settle the soil.
As before, backfill the soil in loosely rather than packing it in with your hands.
Wait a few minutes and watch the water on top of the soil. It should eventually sink into the soil, leaving no puddles behind. The top of the soil should still seem damp to the touch, though.
For each additional oleander plant, follow the same instructions regarding how large to make the hole and how to fill the hole in.
Even though established oleanders can resist drought conditions, they thrive when they receive an occasional deep watering. If the leaves begin to yellow, however, the plant is receiving too much water. Remove any leaves that have completely yellowed and allow the oleander to remain dry for a longer period of time.
You could use a mild fertilizer with balanced amounts of phosphorus, potassium, and nitrogen in the spring if the soil is especially nutrient-deprived, but only do so within the first few years. After the plant establishes itself, switch to a light compost instead of an actual fertilizer.
Mulch added in the spring protects the plant against weeds and allows the roots to remain moist. Mulch added in the fall can help insulate the root system and protect the plant against cold weather. Use an organic mulch, like wood chips or grass clippings.
Do not wait too late into the fall to do this, however. New growth needs several weeks to harden itself before the frost comes.
You must remove wood that has been damaged by the cold, pests, or disease. Also remove overgrown and intertwined wood. During the spring, you should also remove suckers from the bottom of the plant since they can drain the plant’s resources and reduce its flowering ability. Trim down the plant to its desired size, cutting it back to a place just above a node on the stem. The leaf node is a section where three leaves come out from the branch. Making the cut here will force new branches to form at the node, and you will get three new branches when the plant grows back. Avoid pruning more than one-third of the plant when possible. Oleanders can recover if you prune more, but severely heavy pruning can weaken it some. Usually, oleanders grow rapidly, extending themselves by another 1 to 2 feet (0. 30 to 0. 61 m) (30. 5 to 61 cm) per year. If left unattended, oleanders can reach heights between 8 and 12 feet (2. 4 and 3. 7 m), and they can grow as wide as they are tall. Some oleander plants have even been known to reach 20 feet (6. 1 m) (6. 1 m). Dwarf varieties, however, usually stay between 3 and 5 feet (0. 9 and 1. 5 m) tall.
The most common disease faced by the oleander plant is botryosphaeria dieback, and it is most likely to happened if the plant has undergone stress from a drought or freeze. The branches and shoots will die and become a blackish brown. Completely remove the infected branches and dispose of them away from the rest of your garden. Oleander caterpillars are the most common pest. They feed in groups and can demolish young shoots. These pests are about 2 inches (5 cm) long with orange-red bodies and black tufts of hair. Quickly apply a pesticide as soon as you spot multiple caterpillars on your plant. Aphids, mealybugs, and scales can also cause problems, but are rare. Apply an appropriate pesticide as needed.
