Enhance the beauty of grasses with adjacent plantings
It's the time of year when ornamental grasses are one of the few remaining interesting plant types in the landscape here in the mid-Atlantic. While we usually consider grasses as informal elements, some types work just as well in more formal designs. For example, Calamagrostis acutifolia 'Karl Foerster" below (feather reed grass), grows in a narrow column that works well in designs with strong, straight lines.
With a few exceptions, grasses tend to look best when planted in groups or massed. (Pampas grass grows so large it can be used effectively as a single specimen plant.) Even when grouped, what other shrubs and perennials should you consider planting with them? Here are some ideas.
Many of the most popular ornamental grasses are dormant in winter and spring, and only start emerging with new growth in warm summer temperatures. In fact, most people cut back the grasses in late fall - early winter, which can leave bare spots in the garden for half the year. So one strategy is to interplant spring blooming perennials or bulbs to fill in when the grasses are dormant and short. This is a good opportunity to use perennials that die back or lose their luster in late summer and fall, just in time for the grasses to take center stage.
Some perennials to consider include: Tulips and Daffodils, Bleeding Heart, Leopard's Bane, and Columbine.
Many grasses will have natural, tan colored stalks or flowers some time in their growing season. Thus, a nice color based companion would have red or burgundy foliage or flowers appearing at the same time. Ninebark, Smokebush, 'Wine and Roses' Weigela and red Knockout Roses are shrub options that fit this profile.
Those grasses that have/will have red-burgundy stems or flower stalks, such as Pennisetum 'Rubrum' or Andropogon geradii 'Red October', pair well with gold foliage or flowering plants such as Rudbeckia or Gold Mops False Cypress
Grasses that turn gold-orange, such as Big & Little Bluestem, look great with purple flowering plants such as Aster, Agastache, Russian Sage and Monkshood.
Grasses have a light, feathery texture and structure that can be optimized with an opaque background or foreground. Plant tall evergreen shrubs in the back or low height evergreens in front.
A "feathery vs. dense" contrast can be also achieved with adjacent plants like Hydrangea paniculata, with its large, white-pink flower clusters or by planting mums in front of the grasses.
Theme - Naturalistic Synergy
Lastly, build on the naturalistic appearance of grasses by pairing them with Informal perennials or wildflowers that bloom in Fall. Consider Goldenrod, Helenium, Mist Flower, Boltonia and Stonecrop Sedum.