Raised troughs are a great way to grow small drought-tolerant perennials, succulents, and alpine plants. Here are some of the best.
Also sometimes called pinwheel plant for the arrangement of its leaves on shrubby upright stems, aeonium adds height to a trough garden planter. This native of the Canary Islands and Morocco thrives in dry, sunny conditions.
Name: Aeonium spp.
Size: 6-20 inches tall and wide
Zones: 10-11
Top Picks: Zwartkop pinwheel plant (A. arboreum 'Zwartkop') has purplish black leaves at the tips of 2-foot-tall woody stems.
Kiwi aeonium (A. hayworthii 'Kiwi') has medium green leaves edged in red and gold. It is sometimes sold as 'Tricolor'.
Hen-and-Chicks
Hen-and-chicks is a tough succulent groundcover that slowly spreads by producing offsets. It's well suited for growing in trough planters because of its shallow root system. It also grows well in cracks and crevices in rocks or as part of a green roof garden. Pink or yellow flower stalks rise to a foot above the foliage.
Name: Sempervivum spp.
Size: 3-6 inches tall and wide
Zones: 4-8
Top Picks: Common hen-and-chicks(S. tectorum) comes in many outstanding cultivars with colors ranging from blue green to the fiery-red 'Sunset'.
Cobweb hen-and-chicks(S. arachnoideum) gets its name from the mat of white hairs that covers its leaves.
Hairy hen-and-chicks(S. ciliosum) also has white hairs covering its stiff, densely packed leaves.
Octopus hen-and-chicks(S. octopodes) develops offsets at the end of runners several inches long, which makes it resemble the arms of an octopus.
Bellflower
There are hundreds of species of bellflowers available, but the low-growing clumping kinds are best suited for galvanized troughs. They bear blue or white dainty bell-shape blooms.
Name: Campanula spp.
Size: 4-12 inches tall; 4-24 inches wide
Zones: 4-7
Top Picks: Blue Clips Carpathian bellflower (C. carpatica 'Blue Clips') and its sister variety 'White Clips' are clump formers that bloom much of the summer with upturned cup-shape flowers.
Fairies thimbles(C. cochleariifolia) is a slowly spreading creeper with dangling white, blue, or lavender flowers.
Dalmatian bellflower(C. portenschlagiana) bears bluish-purple blooms in early summer on a tidy groundcover plant.
Birch Hybrid campanula (C. 'Birch Hybrid') blooms all summer long if deadheaded.
Catchfly
German catchfly is named for its sticky stems, which sometimes trap or catch small insects. It's a late-spring bloomer with hot pink blooms. This plant loves a hot, dry site.
Name: Lychnis viscaria
Size: 12-18 inches tall and wide
Zones: 4-8
Top Picks: 'Splendens Plena' is a double-flowered form that's evergreen in warm climates.
Cobweb hen-and-chicks(S. arachnoideum) has loose rosettes of green leaves and produces pinkish-purple blooms in spring.
Hairy hen-and-chicks(S. ciliosum) also has white hairs covering its stiff, densely packed leaves.
Octopus hen-and-chicks(S. octopodes) develops offsets at the end of runners several inches long, which makes it resemble the arms of an octopus.
Purple Rock Cress
