Herbaceous Perennials

New Zealand Journal of Agriculture, Volume 84, Issue 3, 15 March 1952, Page 252

Herbaceous Perennials

“THE herbaceous border, though it requires considerable care I and attention, is when properly planned, planted, and maintained one of the most attractive garden features. In this month's article for the flower gardener, C. K. Ellis, Horticulturist, Department of Agriculture, Dunedin, discusses the planning and planting of herbaceous borders and gives lists of suitable plants. GENERAL cultivation and management of a herbaceous border are comparatively simple, provided that the border is confined to the growing of herbaceous perennial plants. Most of these plants become dormant during winter, usually dying back in autumn to a perennating root or other part of the plant. By preparing the area thoroughly and planning it carefully before planting the necessity for lifting, dividing, and replanting should be avoided for 3 or 4 years. The planning of the herbaceous border requires considerable thought and cannot be done in a few minutes. There are three chief aims in the initial planning: To provide a continuous display of colour for as long a period as possible; to provide interest by form and foliage as well as by blooms; and, at all costs, to avoid bare, uninteresting gaps at any time.

Once the general shape and desired pattern of the border have been decided the border should be divided

roughly into front, middle, and back sections. The three divisions must be made to accommodate plants of varying sizes dwarf, medium, and tall. Species for Various Sections The first aim in planning the front section should be to incorporate a number of plants of tidy appearance with semi-permanent foliage, such as aquilegias, heucheras, and violas. A number of late-summer and autumn-flowering types such as summer chrysanthemums, heleniums, and asters, whose foliage remains neat throughout the growing

season, should also be used. Grey foliaged plants are also a very valuable asset in the front section. For best effect all late- and early-flowering species and varieties should be interplanted. The middle section of the border is most likely to be the focal point, and for this reason chiefly, this section should have the early-flowering plants such as delphiniums, anchusas, oriental poppies, and lupins. By the time these plants have finished flowering the species in front will have grown tall enough to hide any untidiness that remains. Summer-flowering bulbous plants of a tall-growing type may be used with excellent effect in the middle section to provide the colour display after the early subjects have finished flowering. Gladioli and many lilies are useful here. Interspersed among the earlyflowering types and the bulbous plants in the middle section should be some later-flowering subjects, preferably with neat growth habit, such as phlox, aster, and helenium. Solidagos, Chrysanthemum uliginosum, tall asters, and all other highgrowing perennials must be placed in the back section, although occasional clumps of them brought forward into the middle section add much interest. A few plants with open growth habit, such as Gypsophila paniculata, can be grown in the back section to fill spaces between clumps of very erect growth. Everlasting peas or clematis species trained over a fence or old stumps as a backdrop complete the picture. Staking Even the best-planned borders can be untidy if plants are allowed to grow without attention. The whole purpose of planning is destroyed if plants are allowed to fall over as they reach maturity and begin to flower. A small amount of time spent in staking is all that is necessary. Staking should not be left until plants fall over; it should be done progressively

during the growing season. It is not hard to place stakes so that they are concealed when plants are in flower. Flower Garden Work for April Begonias in pots should be dried off gradually by giving them less and less water until the leaves and' stems turn

yellow. When the plants are dormant the pots should be put in a dry, frostproof place. Fibrous-rooted begonias should be lifted from the borders when autumn frosts cause growth to cease for the year, set closely in boxes, and stood in a sheltered, frost-free place for the winter. Plants can be started into growth next spring and new plants propagated from cuttings.

Bulbs in bowls potted up and stood out in a cool place to root should be cleaned up and taken into the house as soon as shoots appear above the soil. They should be put in a cool room at first and watered sparingly. If bowls of bulbs are not given this period of rooting at a low temperature, the leaves start to grow before there is

an adequate rooting system to support them, and the flowers are not as fine as they should be.

Bulb planting should be concluded in April, except in warm northern districts, where tulips are better kept in a cool place until May before being planted out. There is no point in keeping bulbs out of the ground longer than necessary, as they shrivel and deteriorate, and bulbs not planted at the proper time cannot be held over until the following season like many sorts of seeds.

Chrysanthemums should continue to be disbudded as the flower buds develop. Though stems with a single bloom are usually considered best for cutting, there is no need to take off too many buds from plants grown solely for border display. However, it pays to remove a proportion of buds even from border chrysanthemums, especially the buds growing from the stem below the main flower cluster, and also to remove side shoots growing from lower down the stems. That involves a certain amount of - trouble, but much improves the appearance of the plants when in flower. Chrysanthemums not yet fully staked should be supported at once, as the stems rapidly become top heavy when the flower buds swell. In districts liable to heavy frosts the late varieties of , chrysanthemums can now be wrenched, lifted, and carefully replanted in a glasshouse or in a sunny, sheltered place where the blooms can be protected from frosts. Plants should not be. packed too tightly together, because if this is done, the leaves will be . attacked by chrysanthemum

mildew. Chrysanthemums growing in pots should be fed regularly with liquid manure.

Dahlia roots are tender and are killed by hard frost. In districts where the ground is likely to freeze hard in winter dahlias should be cut down to about 6in. above the ground before the first hard frost is likely and after the plants have finished flowering. Labels should then be tied to the bases of the stems to identify the varieties and the tubers lifted carefully with a spade and set aside in an airy, frost-free place to dry. When dry the roots should be stored for the winter in a cool shed where they will be safe from frost. In most districts in New Zealand the roots can be left safely in the ground for the winter, but lifting and storing them leaves the ground clear for digging over in winter and eliminates the risk of losing the roots in winters which are exceptionally severe for the district.

Fuchsias growing in pots are usually dried off in April, though the soil in the pots should not be allowed to become completely dry. If desired, pot fuchsias can be kept growing throughout winter on a sunny windowsill, and often will bear flower buds, though these usually fall off before they open. The plants should be kept drier than during summer and autumn and pruned back hard in spring to start them into growth again and prevent them from becoming too large for use in the house.

Gladioli should continue to be lifted and dried off when the leaves show an obvious change of colour; plants lifted earlier and now dried off can be prepared for storage by cutting off the leaves an inch or so above the corms and rubbing off the old, shrivelled corms. The skins should not be removed until spring, as corms keep better in store with their skins in place. Seedlings sown last month should be kept growing strongly until they each have two leaves, after which they should be watered less and less and gradually dried off.

Herbaceous perennials which have finished flowering should be cut down to within a few inches of the ground, the stubs being left to mark the positions of the roots. Plants which have been in for several years and need dividing can be lifted now, the ground dug over, and well-rooted pieces of the plants replanted. Gaps in the border can also be planted up now, making proper use of the perennial scabious, pyrethrums, delphiniums, aquilegias, and perennial phlox, all of which are worth a place in every mixed border and do not spread unduly.

Cuttings from the frame should be planted out as they root and Iceland poppies and other seedlings planted from the boxes in which they have been grown. Sturdy antirrhinum seedlings found growing in the borders can be transplanted to fill up gaps and all pansy, viola, Canterbury bell, gaillardia, and hollyhock plants still growing in frames or nursery beds should be planted into the borders where they are to flower next year.

Pot plants growing in the house should be washed by being held upside down under a cold tap. This washes off pests such as red spider, thrips, and aphis and freshens up the plants. Leaves which show small, whitish dots on their upper surfaces or become rust coloured indicate that red spiders are feeding on the under

sides. Red spiders can be seen with the naked eye, often moving beneath a thin webbing. Pot plants still growing strongly should be fed regularly with liquid manure or complete fertiliser of a suitable grade. Geraniums and balsams which have grown too big to be accommodated on windowsills should be pruned hard, the old, leggy growths being removed; new shoots will soon grow from the bases of the plants. If plants are grown in a window where blinds are drawn at night, it is worth while to have the window ledge widened by the addition of a strip of wood so that the pot plants can stand well , away from the window and the drawn blinds do not touch the pots. If blinds or fringes come into contact with the pots, they absorb moisture that may stain the fabric and such stains are hard to remove. Shrubs which are to be moved and were partly wrenched last month should now be prepared further; the rest of the shrub should be dug round and the remaining roots severed some distance from the trunk. The shrubs, which should not be moved for 6 to 8 weeks after being wrenched, will now have little anchorage and should be supported with strong stakes to prevent them from being blown over. Stakes can be preserved by. dipping them in a proprietary wood preservative. Another very satisfactory way of lengthening the life of manuka stakes is to dip them in creosote and then plunge the butts into hot tar for the depth to which they will be embedded in the ground. Stakes treated this way last for up to 8 years if well stacked off the ground when not in use. Thinning annuals sown earlier should be continued and annuals and bedding plants which have finished flowering should be pulled out. Faded and dead flower heads should be taken off regularly week by week.

Hydrangeas should be pruned, if that has not been done in relatively mild districts. Plants to Propagate this Month Buds inserted earlier should now be established. Ties should be cut before the swelling stems cause them to bite into the bark. Cuttings of many perennial plants such as geraniums, hybrid wallflowers, catmint, and marguerites will still root if put in cold frames. Viola cuttings may also be taken, using only young, strong shoots. This is the season to start taking hard-wood cuttings of shrubs; they should be 6 to lOin. long, and with evergreens the lower leaves should be removed. Among the many shrubs easy to propagate in this way are Lonicera nitida, escallonia, privet, and flowering currant. (A hard-wood cutting is one in which the whole stem is woody to the tip.) The cuttings should be inserted firmly in the soil with about half their lengths buried. Lift, divide, and replant pinks, double daisies, and herbaceous perennials which have finished flowering. Plant out cinerarias (in a semi-shady place), Iceland poppies, forget-me-nots, wallflowers, ana other bedding plants that will make a showy display in spring. Planting should be done as soon as summer bedding plants and annuals have been removed to give the new plants the benefit of the warmth which is still in the soil. If planting is delayed unnecessarily, the plants have less chance of becoming well established before cold weather sets in. Sow a further batch of annuals for early flowering in the warm, northern districts, where most of the hardy annuals will grow steadily all through winter.

Herbaceous Border Perennials and their Flowering Seasons Spring Echinops ritro Late Summer and Early Alyssum saxatile Erigeron speciosus Autumn Arabis Funkia sieboldi Aubrietia Gaillardia grandiflora Achillea, The Pearl Doronicum Galega Acomtum fischen Iberis , Geranium ibericum Anemone japonica Polyanthus Geranium grandiflora Aster spp. Saxifraga cordifolia Geum Chrysanthemum Late Spring and Early Gypsophila “Bristol Fairy” Echinacea purpurea Summer Gypsophila paniculate, Gladiolus Aquilegia hybrids ffeliopsis scabra Selenium Dielytra 1 Hemerocallis aurantiaca Kniphofia Geum Inula glandulosa Montbretia Honesty (lunaria) Iris germanica hybrids Rudbeckia Iris germanica hybrids Linum perenne Solidago Papaver orientals Lupinus polyphyllus Autumn Saaifraga cordifolia Lychnis spp. Achillea, The Pearl Summer thrum salicaria Aconitum fischeri Achillea spp. Monarda didyma Aster spp. Aconitum (Spark’s variety) Monarda violacae Chrysanthemums Anchusa italica Dromnore Nepeta mussini Helianthus Anchusa italica Opal . Oenothera glauca Iris foetidissima Anemone japonica alba Paeonia. Kniphofia Anemone japonica Papaver orientate - Nepeta . mussini Bocconia cordata Pentstemon spp. Physalis alkekengi Campanula latifolia Phlox decussata Rudbeckia Campanula persicifolia Potentilla Solidago canadensis Carnations Pyrethrum Schizostylis Centranthus spp. Scabiosa Caucasian Winter Chrysanthemum maximum Sidalcea HeUeborus niger Coreopsis grandiflora Statice latifolia Iris stylosa Delphinium Thalictrum Kniphofia (tritoma) Dianthus (pinks) Tradescantia Petasites fragrans Dictamnus caucasicus Verbascum Schizostylis coccinea Dielytra spectabilis Veronica spicata Sternbergia lutea