Hebe it is marginally hardy in North America, often suffering from winter damage if winters are colder than normal. In general, the smaller the leaf, the better the cultivar or species can tolerate cold. Protection from drying winds, particularly in winter, will help Hebe survive in cold climates.

Hebe grows best in full sun or part sun and well-drained, sandy soil. Too much shade and it will become leggy and might cease blooming. Although relatively drought-tolerant, this shrub requires about an inch of water a week in summer to maintain healthy, robust foliage and produce large, color-drenched blooms.

You can plant Hebe all year long where it is hardy, but spring or summer planting will give roots a chance to settle before cold temperatures arrive. Speaking of cold weather, this shrub has a better survival rate when sheltered by a building or other plants. If you want to plant it in an exposed location, choose a compact variety that is less likely to be affected by low temperatures.

In spring, feed Hebe with a slow-release fertilizer before new growth begins. Most of these shrubs maintain an attractive form with limited pruning. If one starts to become leggy, you can cut it back by one-third to create denser branching and a neater form. Because Hebe blooms on new wood, it is best to prune this shrub immediately after flowering so you don't lose next year's flowers. Feel free to remove broken stems or those that suffered winter damage at any time.

It is also possible your shrub has suffered from sun and heat scorch from our unusually hot dry summers.

Hebe is not commonly afflicted by pests or diseases, so it is most likely environmental or mechanical damage of some kind.

Hope this helps!