Mulch the soil around the base of your ornamental cherry tree. Spread a 4- to 6-inch layer either out to the drip line of the branches or in a ring 3 feet in diameter around the trunk. Use an organic mulch, such as wood chips or shredded bark. This will conserve moisture and discourage weeds and turf from competing with your tree for water and nutrients.
Prune to remove dead or diseased branches. Also cut off older branches that are bare of foliage or blossoms along their length, with the growth appearing near the end of the branch. The best time to prune ornamental cherry trees is in late spring or early summer; the cuts heal faster at this time.
Water every 10 to 14 days during the growing season. Put a garden hose near the base of the tree and allow a trickle of water to slowly seep into the ground around the base of the cherry tree. Leave the hose running for one to two hours, until the ground is wet 10 to 12 inches below the surface. This will encourage your ornamental cherry tree to put down deep roots, making it less susceptible to drought or damage from high winds.
Fertilize ornamental cherry trees in early spring and again in early summer. Spread slow-release granulated fertilizer, specially formulated for fruit trees, around the base of the tree, out to the drip line. Pull back the mulch and sprinkle the fertilizer on the soil following the manufacturer's recommended rate of application. Scratch the fertilizer into the soil with your garden claw or digging fork. Replace mulch.
Inspect your tree monthly for signs of aphids, which are a common pest of ornamental cherry trees. They appear as small white insects that cover small twigs and the underside of leaves. Aphids suck the sap from their host plant and weaken it, making it further susceptible to other pests and diseases. Release large quantities of purchased ladybugs near your ornamental cherry trees. The ladybugs eat aphids.
Clean up fallen autumn leaves to reduce the possibility of disease or mold forming in the leaves around the base of the tree and harming it.