Plants - Trees and Shrubs

Shrub subs

By
Larry Hodgson
Photography by
Aleksandra Szywala

Once considered old-fashioned, flowering hedge perennials look new again

To prepare a place for the new hedge, first create a straight line using a string pulled taut between two stakes. Using a sharp spade, mark the sod (or earth) along this line, then dig out a 45- to 60-centimetre-wide trench behind it, as deep as the plant's root ball. Since most perennials are comparatively shallow-rooted (peonies are an exception), 15 centimetres deep is usually sufficient. If the soil is clay, build up a small berm (about 10 centimetres high) of top-quality soil before planting the hedge to allow its upper roots to grow in lighter soil. Mix plenty of compost into the soil removed from the trench: a 50/50 blend should give you decades of good performance.

As with shrub hedges, space hedge perennials up to twice as close as normally recommended. Lightly dust the bottom of the planting trench with mycorrhizal fungi, which allows the plant to take up more nutrients from the soil, being careful not to breathe it in if you're allergic to dust. Then place plants in the trench and backfill with soil, watering well. Add a thick (eight- to 10-centi-metre) layer of mulch to discourage weeds and conserve moisture.

For healthy growth, apply slow-release organic fertilizer in spring. Some watering may be required during dry weather, but most mature hedge perennials are drought-resistant. Top up mulch as it decomposes. You can remove faded flowers; however, many dry beautifully, and some hedge perennials have interesting seed capsules. Generally, fall maintenance isn't required. If you're a stickler for tidiness, though, prune plants down to 15 centimetres; the remaining stubble will trap snow and falling leaves for winter protection. In spring, once the snow has melted, cut back any remaining old stubble to about two centimetres.

Most hedge perennials will bloom for 20 years or more without needing to be divided-some last more than 100 years -- but if plants become weak or bloom less abundantly, dig them up, divide them and replant the hedge in renewed soil.

Not all perennials make good hedge plants. Look for plants that will grow at least 75 centimetres tall, 120 minimum for privacy. Avoid floppy or short-lived perennials or those needing regular dividing, such as many asters. Invasive plants are also bad choices. The good hedge perennial forms a thick clump, but doesn't spread. Avoid plants susceptible to insects or diseases in your climate, or look for disease-resistant cultivars.

Sources
Key:
Amsonia hubrectii: 1,
A. tabernaemontana: 2,
Aruncus dioicus: 3,
Asclepias incarnata: 4,
Asparagus officinalis: 5,
Baptisia australis: 6,
Calamagrostis x acutiflora 'Karl Foerster' syn. 'Stricta': 7,
Chelone obliqua: 8,
Cimicifuga racemosa: 9,
C. r. 'Brunette': 10,
Crambe cordifolia: 11,
Dictamnus albus: 12,
Echinops sphaerocephalus: 13,
hemp agrimony (Eupatorium cannabinum): 14,
E. fistulosum: 15,
E. maculatum: 16,
E. perfoliatum: 17,
E. purpureum: 18,
Filipendula rubra: 19,
Hemerocallis hybrids: 20,
Kirengeshoma palmata: 21,
Lavatera thuringiaca: 22,
Miscanthus sinensis: 23,
M. s. 'Silberfeder': 24,
M. s. 'Silber-spinne': 25,
Osmunda regalis: 26,
Paeonia lactiflora and hybrids: 27,
Persicaria polymorpha: 28,
Phlox paniculata: 29,
P. p. 'David': 30,
P. p. 'Shortwood': 31,
Thalictrum aquilegiifolium: 32,
T. delavayi: 33,
T. flavum: 34,
Vernonia noveboracensis: 35,
Veronicastrum virginicum: 36.

Dinter Nursery Ltd.: 1- 4, 7, 10-13, 18, 21, 22, 24, 26, 27, 30-32, 35, 36.

Blomidon Nurseries Ltd.:
1-4, 6-8, 10-13, 18, 21, 22, 24,
26-28, 30, 32, 35, 36.

Bluestem Ornamental Grasses: 7, 23.

Botanix Azilda Greenhouses:
3, 6, 7, 10, 12, 19, 20, 24, 29, 32.

Canning Perennials: 2-7, 10-12, 15, 16, 20, 26, 34, 36.

Fraser's Thimble Farms: 4, 8, 10-12, 14, 18, 19, 21, 30, 33.

Greengate Garden Centres Ltd.: 1-4, 7, 8, 10, 12, 13, 18, 21, 22, 24, 26-28, 30-32, 35, 36.

Humber Nurseries Ltd.: 7, 26.

JDS Gardens
2277 County Rd. 20, RR 4, Harrow, Ont. N0R 1G0; 519-738-9513: 3, 4, 6, 8, 10, 11, 20, 21, 23, 28, 29, 32.

Mason Hogue Gardens: 2-4, 6-9, 12, 14, 21, 24-26, 32, 35, 36.

Ontario Native Plants: 4, 16, 17.

Peter Knippel Nursery Inc.: 1-5, 7, 8, 10-13, 18-22, 24, 26-32, 35, 36.

Sunshine Coast Nursery: 1-5, 7-13,
18-32, 35, 36.

Whitehouse Perennials: 3, 6-11, 16, 20, 24, 27-30, 32, 36.

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