Plumeria trees (Plumeria spp.) add a tropical touch to your garden or patio. The trees are especially noted for their fragrant flowers and showy foliage. But plumeria trees don't grow as perennials outside of U.S. Department of Agriculture plant hardiness zones 10 through 12. That puts Pennsylvania gardeners, who have decidedly non-tropical winters, out of the running for growing the scented trees in the ground. Instead, grow the small trees in large containers to grace your patio in summer.
Set the potted plumeria outdoors in full sun or part shade once temperatures are reliably above 40 degrees Fahrenheit. In Pennsylvania, you may have to wait until June, or plan to bring the container inside during cold snaps.
Water the soil around the plumeria on days in which there is no significant rainfall. In Pennsylvania, you can expect 3 to 4 inches of rainfall per month, which is not enough for a potted tree. Give the plumeria at least 1 gallon of water every day, which will give the tree slightly more than 1 inch of water per week.
Stick the probe of a moisture meter into the soil to determine if your plumeria is getting enough water, especially in hot weather. Water the plant if the meter indicates low moisture.
Mix 1 tablespoon of 15-30-15 water-soluble fertilizer with 1 gallon of water, or according to package instructions. Pour the solution into the soil around the base of the tree twice a month, instead of plain water. Check the package instructions as rates and methods vary by brand.
Check the plumeria's leaves carefully for pest problems at least once a week. Signs of spider mite damage include white, yellow or brown spots on the leaves, as well leaves dropping. You may also see the tiny orange creatures themselves, especially on the undersides of leaves. Mealybugs and other scale pests are bumpy-looking insects that nestle into the woody or leafy parts of trees. If you don't see the scales, the damage they cause includes yellowing leaves, stunted growth and the sticky residue known as honeydew.
Blast trees with a garden hose if you see pest damage. This is usually enough to dislodge bugs, such as lightweight spider mites.
Coat affected plumeria parts, including branches, trunks, leaves and flowers with a ready-to-use insecticidal soap. Scale infestations often require heavy spraying to coat the pests as well as the affected plumeria parts. Spray all parts of the plant because insecticidal soap only kills the bugs it touches.
Bring plumeria inside in the fall once night temperatures begin to dip below 45 F. In Pennsylvania, this will likely be around October.