Monday, January 17, 2011

Purple Pennisetums

When April and May come around, we are all starved for those bright colors which is only to be expected. However, remember that dark foliage plants not only are great companions for brighter neighbors but create depth in the garden. At RBG, we've put a lot of time in to offering colorful foliage from our woody plants, perennials and annuals. I was working on a presentation today that revolves around my favorite annuals and not only did I notice that foliage interest was predominant but I kept adding various annual fountain grasses (Pennisetum sp.) that are quite dark and textural. Above is the variegated purple fountain grass (Pennisetum setaceum 'Fireworks') that was a huge hit in 2010 around the gardens. This was a primary component of our maroon and red theme and the pink highlights fit right in to our arrangements. To the right is 'Fireworks' fountain grass in front of the purple elephant grass (Pennisetum purpureum 'Prince') that I'll mention later. It is fairly easy to locate the standard purple fountain grass (Pennisetum setaceum 'Rubrum') at garden centers (always support your local garden centers!!!) and it will always be one of my favorites (see directly below and the bottom photo). This non-hardy grass grows quickly, offers that deep maroon in a sunny landscape and the showy inflorescences from mid-summer until frost. The specimen below was blended with bronze fennel (Foeniculum vulgare 'Dulce') which offered a nice color accent.
We've had some fun with some of the larger maroon elephant grasses (Pennisetum purpureum) that are native to Northern Africa and are normally green. It is important to note that we see no flowering on these elephant grasses as our season isn't long enough but the foliage contribution is extraordinary. Full sun is a must for the darkest coloration and more water plus occasional fertilizer will increase size significantly. We grew 'Prince' many years ago and saw it top out at 8' tall! To the left is a specimen from 2010 that was over 9' tall. It takes up a sizeable amount of real estate so keep that in mind in terms of proximity to other plants. The variety 'Princess' is a bit more demure but will get a good 5' tall in optimum growing conditions. To the right is a perfect picture for comparison of the two varieties with 'Princess' in the foreground and 'Prince' in the background. These grasses combine well with anything yellow or white (blooms and/or foliage) and are quite statuesque in terms of being a focal point in the garden. To the left is another shot of 'Prince'. Directly below is a border in the Children's Garden from 2010 that included both grasses ('Prince' and 'Princess') and the standard ornamental pearl millet (Pennisetum glaucum 'Purple Majesty') that looks like maroon corn with dark, "cattail-like" blooms (left side of the image). While the elephant grasses are drought tolerant, adequate watering will keep the leaf blades looking vigorous all summer.
While standard purple fountain grass (Pennisetum setaceum 'Rubrum') will vary in mature height between 36" and 48", there has been more developments in the elephant grass (Pennisetum purpureum) cultivars for some varieties shorter than both 'Prince' and 'Princess' that tend to be overbearing in a container or smaller garden. It is important to mention that there is a variety of purple fountain grass called 'Burgundy Giant' which tops out at 5' and was introduced by Longwood Gardens. It can be seen to the right but it sure looks alot like the standard Pennisetum setaceum 'Rubrum'. Directly below is a neat medium-sized purple pennisetum (Pennisetum glaucum) called 'Vertigo' that is part of the Proven Winners Graceful Grasses program. We've not tried it yet at RBG but I've seen it grown and it is very dark in full sun and around 48" at maturity. The picture below is from the West Madison Agricultural Research Station. The Athens Select Program at the University of Georgia has introduced some small elephant grasses that combine the benefits of deep maroon foliage but with a smaller stature. Two pictures down is 'Princess Caroline' from Athens Select that is glossy, dark maroon and 36" tall. Not pictured, but even smaller is 'Princess Molly' which gets 20" or so and is ideal as a container centerpiece. I've thrown a lot of varieties at you but keep your eyes peeled this spring for purple pennisetums for your landscape.

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