The Name Watermelon Red Crape Myrtle. This crape myrtle bears watermelon red flowers in a shrub to small tree form. It is however, mildew susceptible. The quintisential tree for the Southern garden, form may range from upright and vase-shaped to low, horizontal, and shrub-like. Mid to late summer flowers range from pink, to white, to red, or lavender and variations of. To encourage a second flush of flowers, remove old flowers with hand pruners. Seed heads follow flowers and persist throught the winter, adding an ornamental quality. Fall color ranges from orange to red, and smooth grey to reddish-brown bark is attractive year round. Crepe myrtles should be grown in fertile, well-drained soil in full sun, in open areas where air circulation is good. In cooler areas, the crepe myrtle is grown more like a flowering shrub, that is pruned back hard to the ground each year. This is a massive no-no in zones 6b and higher. Prune to encourage a tree-like form, removing only suckering inner shoots, crossing branches, and side shoots 4 to 8 feet from the ground. If you can't remove side shoots with hand pruners, you should probably leave them. Lower suckers may be removed with loppers.