By: Susan Patterson, Master Gardener
Oleanders (Nerium oleander) are beautiful mounded shrubs with glossy leather-like evergreen foliage and brilliant blooms. Dwarf varieties reach 3 to 5 feet (1 to 1.5 m.) at maturity while full-size shrubs will grow up to 12 feet (3.5 m.) tall and 12 feet (3.5 m.) wide.
Pruning oleander shrubs is not necessary for health but will keep the shrub tidy and control growth. The time to prune oleanders and how to prune an oleander for best results are important considerations whenever oleander trimming does become necessary.
When to Prune Oleanders
To ensure the vitality of your oleander, prune at the appropriate time. Because they have a very short bloom time, the best time to trim oleanders is right after they bloom. For varieties that bloom well into the fall, it is imperative to have them trimmed by mid September.
Having the right tools makes pruning oleander shrubs easier. Hand pruners and loppers are usually sufficient to trim oleanders. Make sure that your tools are in good working order and sharp. Wipe all debris from your tools using a clean rag, soak them in a solution of one part bleach and three parts water for five minutes, and then rinse with clean water. This will help reduce the spread of pathogens.
How to Prune an Oleander
Oleander trimming is not difficult but requires some planning. Step back from your bush and formulate a pruning plan in your head. Take note of the desired shape you wish to achieve and get an idea of how much you need to trim away.
Annual pruning of oleander bushes involves inspection for dead or damaged limbs first. Remove these limbs at the ground or at the point where they join a healthy limb. As a rule, do not remove more than one-third of the entire bush. Trim branches just above a leaf node. This will encourage new growth.
Continual pruning in this manner will encourage your oleander to be bushy, rather than tall and lanky. Every two or three years you can prune your oleander for renewal. This means taking more than one-third off and cutting the oleander back aggressively.
Rake up and dispose of all debris after you have finished pruning.
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Can You Keep Oleanders Pruned Short?
Life is either a daring adventure or nothing at all, according to author and activist Helen Keller, and those who aim to prune the oleander shrub (Nerium oleander) regularly should keep this saying on their wall. Oleander is a lovely shrub or small tree with long-lasting, heavy blossoms, but it is also a toxic plant. It grows in U.S. Department of Agriculture plant hardiness zones 9 though 11 and accepts severe trimming, but you had better put on protective gear before you take fate into your hands.
Pruning During Springtime
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In order to carry out the entire process, little care and maintenance is required to keep its natural shape. But if you wish to give the plant a multi-stemmed or single-trunk shape, you would have to invest more time towards pruning.
Despite what you choose, below we have instructions that will give you a complete look at how to go about the task.
- Always water the tree during drought conditions. Although it is resistant to droughts, watering the plant 1 to 2 inches each week while the dry spells are on, will maintain the tree’s energy and production of flowers.
- Remember to remove the suckers from the base of tree. Suckers tend to appear when new growth is found at the bottom of the trunk and also in the ground (around the base of the tree). As soon as you see it sprouting, make sure to pluck it off. Or else, it will steal essential moisture and nutrients to grow properly.
- The ideal time for pruning is anywhere from September to early October. This encourages their growth in spring. While cutting the branches, do so just above the nodes that have like 3―4 leaves. The node of the branch is where the leaves will grow from the branch itself. Once you cut the area, new branches will grow from there and flowers will get a chance to develop at the end of these new branches.
- You can even follow heavy pruning as the plant is used to it. This means, while pruning more branches will make it grow faster and in abundance. While trimming, cut along the top and inside the bush as well to keep the shape. If you wish to grow it into a tree, only cut the lower branches, near the trunk. Plus, remove new growth along the bottom of the trunk, as soon as it shows signs of development.
- Organic fertilizer, once in early spring and again during early fall will assure the growth and flower production. Use balanced fertilizer which contains nitrogen, potassium and phosphorus and make sure to follow the directions given on the package. Or, you could follow the instructions for organic fertilizer recipe, and use the homemade fertilizer instead.
- Now, you also need to be careful with the caterpillars as the insects can wipe out the tree in less than 2 weeks. Snip the affected leaves and stems off that are present with caterpillars. You can also pick it with hands, place in plastic bag, seal it and keep in the freezer for about 24 hours. You can also use pesticides which contain bacillus thuringiensis. This will help treat caterpillars on tall trees.
As all parts of the plant are poisonous, make sure you wash your hands properly after pruning the oleanders. Discard whatever you cut in disposable bags, instead of burning it (the smoke is toxic). Help the trees grow in any desired shape you want, and keep the beauty of this ornamental plant alive.
Got Old, Overgrown Plants? Know When to Prune or Replace
Overgrown plant, old Texas sage (Leucophyllum frutescens ‘Green Cloud’)
You have undoubtedly seen an old, overgrown plants filled with mostly leafless branches that rarely flower anymore. Or, perhaps it is an aged succulent that has brown patches that are slowly encroaching onto the upper parts of the plant from the base. So, what is the solution for plants that no longer add decorative value to our landscape?
Old rosemary filled with unproductive woody growth
While some woody plants such as Texas sage or oleander can be rejuvenated by severely pruning them back, not all plants respond favorably to this and grow out again. Let’s take a look at some Southwestern favorite shrubs and succulents and talk about whether you should prune severely or when it’s best to replace.
Oleander that has undergone severe renewal pruning in spring.
Many shrubs can be rejuvenated by severely pruning them back, which gets rid of old, woody growth and stimulates the production of new branches, which will flower more (in the case of flowering shrubs). It is helpful to think of severe renewal pruning as the “fountain of youth” for many plants. This type of pruning is best done in spring, once the weather begins to warm up. Shrubs that respond well to this include bougainvillea, jojoba, lantana, oleander, Texas sage, and yellow bells. It’s important to note that not all shrubs will come back from this method, but the pruning didn’t kill the shrub – it only hastened the demise of the plant that was already in progress. If this happens, replace it with another.
Old desert spoon (Dasylirion wheeleri)
There are some plants that don’t respond well to renewal pruning or where that isn’t possible to do in the case of succulents. In this case, the solution is simple – take them out and replace them with a younger version of the same plant. Examples of plants that are better removed and replaced include aloe, desert spoon, red yucca (hesperaloe), rosemary, and prickly pear cactus. When you think about it, the cost isn’t very high, when you consider the beauty that these plants added to your landscape for eight years or more.
Heavenly Cloud Texas Sage several weeks after severe pruning.
When you think about it, the cost isn’t very high, when you consider the beauty that these plants added to your landscape for eight years or more.
*Have you severely pruned back an old shrub and had it come back beautifully? Or, maybe you recently removed and replaced some old succulents?
Noelle Johnson, aka, 'AZ Plant Lady' is a horticulturist, certified arborist, and landscape consultant who helps people learn how to create, grow, and maintain beautiful desert gardens that thrive in a hot, dry climate. She does this through her consulting services, her online class Desert Gardening 101, and her monthly membership club, Through the Garden Gate. As she likes to tell desert-dwellers, "Gardening in the desert isn't hard, but it is different."
A Word of Caution
It's imporant to note again that oleanders contain a naturally occurring toxin (cardenolide glycosides) that, when ingested in certain quantities, can be harmful—even fatal—to humans and pets. If an individual comes in contact with any poisonous materials, contact your local Poison Control Center immediately. Learn more from UF Health.
Due to this, using oleander in a landscape should be carefully considered. Parents should avoid planting oleander in their home landscape where there is a potential for small children to consume parts of this plant. When disposing of pruned branches, don't burn them the toxins will become airborne and may cause respiratory difficulties if the smoke is inhaled. Pet owners and livestock producers also are cautioned to place this plant out of the reach of animals who may graze on it. But don't let this stop you from growing this beautiful and tough, low-maintenance shrub if you have the appropriate landscape for it.
For more information on growing oleander, contact your local county Extension office.