when to plant perennials - Knowledgebase Question

berlin, NH
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Question by dgagne
August 22, 2006
Hi. My name is jennifer croteau and I have never grown a garden before of my own. I live in zone 4 and was wondering when is the good time to plant perennials? My fiancee and I are having an outdoor wedding in September of 2007 in our backyard and would like to have some flowers blooming in the back yard at that time. What type of flowers will come up next fall and when is a good time to plant them?

Answer from NGA
August 22, 2006
When planning late season color for the garden, do not forget to go beyond blooms. Many perennials produce brightly colored berries. Shrub and trees change colors and can have foliage just as showy as the blooms. Shrub and tree foliage assists in complimenting and contrasting to bring out the color of late blooms. Green truly is a color to count on in the garden. The various shades of green taken for granted earlier in the year now come into their own, providing contrast with all the yellow, red and brown of late in the season.

Aconitum species and hybrids are among my favorites for late color. You can have a monkshood in bloom from July through mid-December simply by carefully choosing your selection for bloom period. Heights can range from under two feet to well over head-height. There are also monkshoods that take the form of vines. Colors range from white to pink and cream, but they are best known for lavender, purple and blue blooms. Monkshoods are also available in bi-colors. Please note that all parts of monkshood are poisonous and should be planted and handled accordingly. Two companions to consider for monkshood are hardy begonia (Begonia grandis) and maple-leaf fairy candles (Cimicifuga acerina). Both are shorter plants with good foliage contrast in color and texture, while blooming at the same period as the monkshood.

Cimicifuga acerina, the maple-leaf fairy candle, begins coming into bloom during mid-July, but the full compliment of bloom stems and flowers happen during the first part of September. The glossy foliage is shaped to resemble the leaves of a maple tree, forming slowly spreading clumps below a foot in height. The willow-like stems are covered with frothy white blooms reaching around eighteen inches to two feet. I find this, along with our native species (C. racemosa), which blooms in July, to be the most dependable when coming into bloom during the hottest and driest parts of our seasons.

Lobelia and some of the named hybrids are among my favorites for fall color. They begin coming into bloom, depending upon species or hybrid, during August and are at their best during September. My favorites are the native great blue (L. siphilitica) and cardinal flower (L.cardinalis). The great blue lobelia can reach up to three feet in height under optimum conditions, but for me reaches around 1 ? to 2 feet. Foliage is fairly large, and the bloom stems are numerous on each plant, covered with dense spikes of soft lavender-blue flowers. Each bloom is specifically designed for bees. The lower lip of the corolla extends to provide a landing pad so the bee can enter the tube for pollination.

Toadlilies (Tricyrtis) are a must-have for the shade garden. All that is required for success is well-drained, humus-laden, soil with a bit of mulch and some shade. Excessive periods lacking moisture will cause browning in the foliage. Numerous species and hybrids offer a size and growth habit to fit almost any shade garden. They can be as small as six inches to three feet or more, in height. Habit may be stiffly upright, arching over from about mid-height, or relaxed and flowing as water down a cliff face. Blooms are generally small in relation to overall plant size, but numerous. Individual flowers are quite intricate in design and I am always reminded of spotted orchids while toadlilies are in bloom.

Your local garden center will have lots of things available for fall color in a few weeks. In addition to the above suggestions, you can plant chrysanthemums, pansies and ornamental kale for September color. I'd choose the plants now and plant them so that by next summer they will be well established and ready to put on a show for your wedding.

Best wishes with your garden!

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