Vitex-TheTexas Lilac (Vitex agnus-castus) - Vitex are typically grown as a multi trunked tree. The multi-trunk look is achieved through pruning. When grown as a tree they grow to about 15 feet. However, some varieties can get as tall as 35 feet. If left alone from seed, the Vitex will grow into a lovely shrub that makes a stunning hedge that can, with regular deadheading, produce those long, lovely flower spikes throughout the summer.