The Best Plants for Tiered Walls

Thrillers

• Thrillers are bold accent elements that create drama and interest in your design. The eye goes straight to them and the rest of the plants complement the main attraction. Thrillers can be plants or a special piece of garden art. They are usually vertical elements. Choose more than one depending on the size of the garden. For evergreen shrubs, choose upright or pyramidal junipers such as Juniperus chinensis "Blue Point" or Juniperus scopulorum "Moonglow," dwarf Alberta spruce (Picea glauca "Conica"), boxwood "Green Tower" or "Green Mountain," Arborvitae "Degroot's Spire" or Chamaecyparis obtusa "Fernspray Gold." Other nonevergreen accent plants to consider are ornamental grasses, agave, giant cactus, yucca, red twig dogwood, hardy banana, canna and Colocasia. If your tiers are at least 10 feet apart from each other, you may want to include a small tree such as Acer palmatum, Acer griseum, magnolia, weeping redbud or a sourwood tree (Oxydendrum arboreum).

Fillers

• Fillers are the workhorses of the garden. They fill most of the space. They may or may not flower. They generally have a mounded shape. If you have a lot of space you need to fill, repeat the same plant in clusters or in multiple locations to create cohesiveness across the entire site. Some appropriate shrub fillers include Spireas, Buxus, Caryopteris, Chamaecyparis psifera, threadleaf Japanese maple (Acer palmatum dissectum), Pinus strobus, Rosa "Knockout," spreading yew, globe arborvitae, Cotoneaster or Weigela. For smaller spaces and with a little more maintenance, perennials can be good fillers too. Consider Peonia, Baptisia, Echinacea, catmint (Nepeta), Salvia, Phlox paniculata, hardy hibiscus, Rudbeckia and Actea.

Spillers

• Cascading plants are an essential part of tiered wall gardens. It is important to break up the hardness of the straight horizontal line and soften the hard effect of the stone. Limit your selection to just a few different types unless it is a very large garden, but repeat the selections generously throughout the garden. Spillers include creeping phlox (Phlox subulata), spreading sedums and sempervivums, Vinca minor; Alyssum, false plumbago (Ceratostigma plumbaginoides), creeping Veronica, blue star juniper, Paxistima cambyi and Kinnikinick (Arctostaphylos uva-ursi).

Other Considerations

• Of course, not all the plants mentioned will be suited to all tiered gardens. All the plants mentioned do have in common the preference for well-drained soil, which is generally the condition of tiered planting sites. They all have low maintenance requirements, which is also usually preferable for tiered hillside gardens. However, take into consideration climate, mature width, height and sun or shade requirements as well as your personal style when choosing exactly which plants to get for your garden. Another consideration when gardening around stone is that the microclimate will be a little warmer than the rest of your yard. The stone retains heat during the day and releases it at night, keeping your plants a little bit warmer during the cold winter season.