Q: What can I use as a summer-blooming shrub, especially if this part of the garden is sunny and somewhat dry? I also sometimes have deer problems.
A: I think St. Johnsworts (Hypericum) are underused, and several species are native here in Maryland, though those might be harder to source. Some of the commonly-grown forms are non-native hybrids, though well-behaved ecologically. (The only locally invasive species, Hypericum perforatum, is fortunately not likely to be sold at a nursery.)
St. Johnsworts bloom anywhere between June and September, prefer direct sun, generally tolerate drought well, and are distasteful to deer. Blooms are nearly always an intense yellow, and some species or cultivars have colorful summer or autumn foliage. A few cultivars have berry-like seeds that ripen by fall and make good bouquet accents. I love the bark on native Hypericum densiflorum – peeling with a smooth underlayer that’s a rich, warm-toned cinnamon-brown that’s especially showy during dormancy.
You’ll find St. Johnsworts sold as both perennials and shrubs, because some species stay low, sprawl like a groundcover, and have stems that aren’t very woody, occasionally dying back in winter as other perennials do. Other species have woody stems and grow to about three or four feet tall and wide. Flowers are loaded with pollen, but no nectar, so butterflies will probably detour while bees and flower flies (predators we like to keep in the garden) will visit. Don’t deadhead developing seed capsules if you want to support Gray Hairstreak butterfly caterpillars, which can use Hypericum as a host plant (among a huge variety of other plants).