The plumeria tree is a beautiful flowering plant that can grow to be up to 8 feet tall. It produces large clusters of fragrant flowers and has a thick, spiny trunk. The leaves are shiny on the top and dull underneath with dark green edges. Plumeria trees usually need very little water or maintenance since they like their soil moist but not wet. But if your plumeria’s trunk starts splitting, then take action right away before it damages more branches.
The following info will give you some ideas about what might cause this issue and ways you can try to fix it:
1) Too much fertilizer intake either through a steady feeding schedule or a heavy diet resulting in excess nutrient/mineral build-up. This is a particular problem with clay pots because the minerals leach from the pot walls and accumulate at the tree’s surface, causing unsightly “burn spots” on its trunk. This type of damage usually occurs during the flowering season when a lot of soft, fresh growth encourages even more nutrients to come into play.
Solution: only use organic-based fertilizers that break down slowly over time and those that are less likely to remain inside the soil medium (e.g., kelp) for too long.
2) Too much water while blooming. It’s simple: flower stalk gets too big for its britches (container). The origins (roots) cannot provide enough water, and the container size doesn’t allow room for growth either; thus, splitting results.
Solution: repot or reduce watering.
3) Low air circulation, particularly when in bloom combined with high humidity. This is caused by using a too-small container and keeping it constantly wet and in a very warm place (e.g., on top of a fridge). The plant normally reacts by forming aerial roots that will eventually grow to the ground and then down, looking for water (or even finding their way to your neighbor’s pool!) This also results in splitting.
Solution: increase air circulation and reduce humidity by allowing the potting mix to dry out between watering.
4) Heavy fruit load. Plumeria flowers are heavy because of their large, thick petals and high sugar content, making the flower stalk heavy. The weight only adds to the already considerable stress on the trunk by strong winds or sudden temperature changes, causing it to split.
Solution: make sure your tree is staked, especially when it is a young plant being grown from a cutting, when flowering (and even before flowering) no matter what type of container you use – whether it’s a traditional plumeria pot, an oblong plastic pot, or anything else.
5) Too deep potting medium combined with low humidity/low air circulation resulting in wood rot. This problem occurs mainly with potted plants kept all the time indoors, but also during very cold winter months when low temperatures may result in rot. The cause is the combination of a too-deep potting medium that retains too much water, combined with low air circulation and humidity.
Solution: allow the top 2/3″ (1.5 cm) of the soil mixture to dry out before watering thoroughly; this way, deep watering will not result in excess waterlogged conditions under the bark for prolonged periods. Increase air circulation by opening your windows or allowing yourself a fan near the plant when possible. Reduce humidity by placing your plumeria in a sunny spot instead of an indoor location with little to no ventilation – such as next to a radiator that emits hot steamy air all day long.
6) Positioning it on top of cold vents or other cold surfaces that steal the warmth. This is a particular problem when your plumeria is in bloom or entering its blooming period because an unprotected trunk has little to no resistance against cold drafts and thus will be more prone to splitting.
Solution: protect your plant by moving it away from indoor cool air sources (such as vents) and placing it in a warmer area instead – ideally where there’s lots of sunlight; this way, you’ll get a better chance that your tree survives winter without any damage or deformation.
This one occurs mainly during the summer months if you live in humid regions and under very arid climates.
7) Very dry weather combined with excessive water loss because of poor potting medium (e.g., bark). The tree will usually do its best to avoid any damage by forming aerial roots that will search for water – even if it means reaching your neighbor’s swimming pool. Eventually, the trunk will give way under the extra weight.
Solution: use potting media less likely to crack/split (such as soil) and create more humidity around the plant with frequent misting or additional plants nearby.
As with any plant, many factors contribute to the plumeria trunk splitting. The best thing you can do for this problem is an expert inspection by a certified arborist or horticulturist to determine what may cause the splitting and how it can be corrected.