Chapter 99 Jacaranda mimosifolia
99.2 Soil: Ericaceous Mix
Ratio: 3 parts bark, 1 part peat, 1-2 parts grit
Add-ins: dolomitic limestone (MAX of 2 lbs/yd), Tree-Tone (15 lbs/yd)
pH: ~5.5-6.0 (acidic)
Moisture: moist. Likes heat and humidity. Keep soils evenly moist year around, and never allow soils to dry out.
99.3 Light
They like a lot of sun and humidity but are vulnerable to trunk scald in areas with high temperatures.
99.4 Cultivation Notes
99.4.1 Potting & Root Pruning
Schedule: repot every second year in spring.
99.4.1.1 Top & Branch Management
Pruning is best done in the winter while the tree is dormant, although weaker branches may be more easily identified during the growing season.
Heavy pruning: young jacaranda trees should be pruned to form one central leader (main trunk) for strength and stability. Otherwise, try to avoid pruning jacaranda because this can force it to grow vertical suckers that can distort the tree’s shape. Seasonal pruning should be limited to removing only broken or diseased branches.
The best time for pruning jacaranda trees is in winter before new growth begins. The tree flowers on new wood, and trimming in late winter stimulates vigorous new growth for the maximum number and size of blossoms. Strong new growth also encourages flowering earlier in the season. Pruning after spring growth begins causes poor flowering.
Select the strongest leader and remove the others. This will become the trunk of the tree. Remove competing leaders every three years until one clearly establishes itself.
Jacaranda trees often produce limbs with narrow crotch angles that are prone to splitting. Remove these problem limbs as they appear.
Fine pruning: jacaranda trees grow very quickly. Rapid growth has soft, easily damaged wood. When done properly, jacaranda tree trimming strengthens the tree by limiting the growth to well-shaped side shoots on a single trunk.
Remove all branches that grow at less than a 40-degree angle to the trunk.
Remove branches by cutting them back to the collar where they attach to the trunk. Never leave a stub.
Remove spindly little stems that grow from previous pruning cuts and shoots that grow directly from the ground. These types of growth detract from the shape of the tree and drain off energy the tree needs to grow and bloom.
Cut back dead and broken branches as they appear throughout the year. Cut damaged branches back to just beyond a side stem. If there are no more side stems on the branch, remove the entire branch back to the collar.
Shorten the new shoots to one or two leaf pairs when four or five have grown. The largest leaves can be cut off at any time during the growing season.
Wiring: wires should be removed after three months at the latest. Wire young shoots when they begin to lignify.
99.4.2 Feeding
Jacaranda does not require intensive feeding. Use a 10-10-10 slow-release granular fertilizer in May and July. Alternatively feed with liquid fertilizer during the growth period every week, in winter once every two weeks.
99.4.3 Pests & Problems
These trees drop constantly drop leaves and flowers; it does not mean there is a problem.
Jacaranda trees have a susceptibility to aphids and root rot. Spray aphids on foliage with insecticidal soap, neem oil or a steady stream of water to eradicate them.
To prevent mushroom root rot, do not over-water.
99.4.4 Winter Storage
Bring pots indoors each fall before frost for overwintering in a bright cool location. In winter, when there is not enough light, the tree can drop all the leaves, but new ones will grow in spring.
99.5 Propagation Notes
Grows easily from seed.
99.6 Artistic & Styling Notes
99.7 Additional Information
99.7.1 Natural History
Jacaranda is a sub-tropical tree native to south-central South America in Argentina and Bolivia. It is a deciduous tree that grows 25-50’ tall in its native habitat. Jacaranda has been widely planted elsewhere because of its attractive and long-lasting violet flowers. It is also known as the blue jacaranda, black poui, or fern tree.
99.7.2 In Cultivation
Jacaranda grown as a street tree. Link to original image.
The blue jacaranda has been cultivated in almost every part of the world where there is no risk of frost; established trees tolerate brief spells of temperatures down to around 20°F. Even when young trees are damaged by a hard frost and suffer die back, they will often rebound from the roots and grow in a shrub-like, multi-stemmed form. Needs summer heat to set flowers.