Perennials for Low Maintenance Gardening Part

Notes from the Arnold Arboretum Perennials for Low Maintenance Gardening - . Part III Iris - Iris, Fleur-de-lis Irises are similar to Daylilies in that there are so many available varieties to choose from that one hardly knows where to begin. For the low maintenance garden the similarity ends here because the Tall Bearded Iris, the most popular of the group, cannot be called an undemanding plant. Clumps may start to degenerate after the third or fourth year and division of these, preceded by a thorough preparation of the new site, may be necessary. The Iris borer, a worm which tunnels into the rhizomes, can cause serious trouble and is more difficult to control now that DDT is not used. A short blooming period restricts the use of irises in most mixed borders, but when planted for mass effects the results are delightful. When used sparingly in a mixed border, the leaves of irises form good contrasts to the foliage of many other types of plants. According to the Popularity Poll in the October 1970 issue of the Bulletin of the American Iris Society, some of the best varieties to watch for in catalogs are as follows: I. ’Stepping Out’ - this is basically a white flower which is heavily overlaid with deep blue-purple edges to the flower segments; 1. ’Winter Olym- pics’ - to date the finest pure snow-white flowered bearded iris; I. ’Rippling Waters’ - a blend of pale lavender-blue; I. ’Esther Fay’ - a very husky growing variety with pink flowers; I. ’Dusky Dancer’ - one of the most popular of the so-called black varieties, the flowers being a deep purple-black; 1. ’Ultrapoise’ - the most popular yellow; I. ’Ginger Snap’ - the best brown; and I. ’Christmas Time’ - snow-white with a fiery red beard. Of greater value in the low maintenance garden are the less numerous cultivars of the Siberian Iris, I. sibirica. Many of these will survive in poor soil, but do better where soil condi- 127 128 tions are rich and moist, and although they will withstand light shade, they are at their best in full sun. A few of the good newer varieties are: I. ’Gatineau’ - large violet-blue flowers; I. ’Ruby Wine’ - bright ruby-red flowers; I. ’White Swirl’ - satin-white in abundance; and I. ’White Magnificence’ - very large white flowers. Kniphofia - Torch-Lily, Red-Hot Poker Kniphofia uvaria is probably the best known species, and although still commonly offered it is not entirely compatible with New England winters, and its bright red and yellow flowers are thought to be overly gaudy by many people. This somewhat unsavory reputation is no longer fully deserved as breeders have developed new cultivars which are hardier and have a better range of softer colors. All Torch-Lilies require sandy, perfectly drained soils. Soggy conditions are fatal, and although a position sheltered from the wind should be selected, they should be situated so as to receive as much direct sunlight as possible. Divisions obtained from nurseries are usually quite small and it will take a few years for them to become established. Plants grow from two to three feet tall, have a somewhat coarse appearance, and are best seen as single specimens rather than massed. Some of the interesting new varieties which should be tried - are: K. ’Earliest of All’ - coral-rose; K. ’Maid of Orleans’ pale yellow; K. ’Primrose Beauty’ - primrose-yellow; K. ’Springtime’ - flowers in the upper part of the spike are coral-red, those below are ivory-white; and K. ’Summer Sunshine’ - flame red. Liatris - Blazing Star, Gayfeather It is rather unusual that a member of the Daisy family should have flowers which are arranged in a dense spike formation. These spikes seldom fail to attract attention because the flower heads at the top open first, and flowering progresses down the stem rather than up. Exceptions to this are L. scariosa ’Septem- ber Glory,’ which produces five-foot spikes of purple flowers which open all at the same time, and its sport L. ’White Spire’ which has white flowers. Although all the commonly grown species produce excellent flowers for cutting purposes, these two cultivars are probably the best. It should be noted, particularly with the shorter-growing varieties, that at least one third of the stalk should be left on the plant after cutting. This will leave sufficient foliage for the manufacture of food reserves. Liatris are stiff, upright plants which look best when planted 129 sparingly rather than as large masses. They will tolerate considerable moisture during the growing season, but soggy soil conditions during the winter will lead to rapid deterioration of the clumps. (This is particularly important with L. pycnostachya, L. scariosa, and their several cultivars.) A moderately fertile sandy soil and a position in full sun are about the only other requirements for Liatris. Stems of the taller growing L. pycnostachya, L. scariosa ’September Glory’ and L. ’White Spire’ have a tendency to lean over under their own weight and require staking. For the low maintenance gardener, several other species and cultivars which do not possess this objectionable characteristic can be recommended. L. spicata with purple flowers in August forms fairly dense clumps with three-foot spikes; L. spicata ’Kobold’ is only eighteen to twenty-four inches high, and has dark purple flowers; L. spicata ’Silver Tips’ grows to three feet tall with flowers more nearly lavender in color. L. punctata, the Dwarf Gayfeather blooms in August and seldom exceeds two-and-a-half feet in height. Limonium - Sea-lavender, Hardy Statice When grouped closely together, plants of Limonium latifolium will form an attractive and somewhat unusual groundcover. When grown in the herbaceous border they may be counted upon to develop into long-lived specimens which will withstand considerable neglect. Established plants bear large panicles of numerous small flowers. These are frequently up to one-and-a-half feet across and can be used effectively in dried flower arrangements. In time, a clump may have up to a dozen sprays and form a spec- tacular canopy nearly a yard wide. Sea-lavender may be used in much the same way as Gypsophila (Baby’s Breath) to impart a light, airy effect in the garden, and is an excellent substitute in areas where Gypsophila does not overwinter well. It is a fitting subject for gardeners near the sea, and inland the major requirement is that plants be grown in a light sandy loam in a sunny position. If planted in a heavier soil, stems will invariably be weak and require staking. Limonium latifolium blooms from July through August and produces bright mauve-lavender flowers. Two cultivars which somewhat extend the color range are easily available. These are L. latifolium ’Colliers Pink’ with pink flowers, and L. latifolium ’Violetta’ with clear violet-blue flowers. 130 Lupinus - Lupine Of the several types of Lupine which are hardy, the strain known as Lupinus xregalis ’Russell Hybrids’ is by far the show- iest. These cannot be recommended for general cultivation in our area, however, because of their sensitivity to hot summers. They do best in cool, humid areas such as northern New En- gland and the Pacific Northwest. It has been said that L. cytis- aides, the Canyon Lupine from California, might be crossed with the ’Russell Hybrids’ to produce a more heat-resistant strain. Until this is done, or summer hardiness is achieved in some other way, gardeners in the Boston area and south should probably avoid Lupines. Lychnis - Campion, Catch Fly, Maltese Cross Although this group produces some of the most vividly colored flowers of any in the herbaceous border, the so-called perennial species are quite short lived and are of no value in a low maintenance garden. Lychnis coronaria, the Rose Campion, usually behaves as a biennial and seeds itself in such a copious manner that it may have some value in certain situations where many chance seedlings would not look out of place. Lysimachia - Loosestrife Most members of this genus would not look well in a mani- cured formal border, but the somewhat spreading (sometimes invasive) tendencies of the more commonly grown species may be a distinct asset in gardens which are to receive minimal care. They are of easy culture and adaptable to a wide range of conditions. Lysimachia clethroides, the Gooseneck Loosestrife, bears three-foot stalks of white flowers which are both attractive and interesting because they bend at the top in a somewhat gooseneck fashion. They last well and can be used for flower arrang- ing. This is not a plant for confined spaces and it would be unwise to place choice smaller plants nearby or to expect it to fit into any ordinary-sized niche in the border. When naturalized, or planted in light shade near the base of shrubs, however, they will be seen to full advantage. Lysimachia punctata, the Yellow Loosestrife, produces sturdy three-foot stems which have axillary whorls of bright yellow flowers over most of their length during June and early July. It does not spread as rapidly as L. clethroides, and although best in partial shade, it will tolerate full sun if planted in rich, moist 131 soil. Another Loosestrife with yellow flowers is L. vulgaris, whose flowers are borne in terminal panicles during late July and August. This species will not tolerate exposure to full sun, and partial rather than dense shade will suit it best. Sometimes called Creeping Jenny or Moneywort, L. num- mularia is a European plant now widely naturalized in North America. Were it not for its overly invasive tendencies, this would probably be one of our best ground covers, but it should not be planted where it cannot easily be contained.

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