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Horticulture Principles and Practices

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TABLE 17–6<br />

Selected Ground Covers That Are Aggressive Spreaders<br />

Plant Scientific Name Zone Comments<br />

Mazus Mazus reptans 5–8 Forms quick ground mat; 1 to 2 inches<br />

(2.5 to 5 centimeters) high<br />

Creeping jenny Lysimachia nummularia 3–8 Stems root rapidly as they spread; 4 to<br />

8 inches (10 to 20 centimeters) high<br />

Creeping lilyturf Liriope spicata 5–10 Rapid rooting; 4 to 8 inches (10 to<br />

20 centimeters) high<br />

Crown vetch Coronilla varia 3–9 Tough ground cover; 18 inches<br />

(45 centimeters) high<br />

Ajuga Ajuga reptans 3–8 Short (3 inches or 7.7 centimeters);<br />

forms solid carpet<br />

Bishop’s weed Aegopodium podagraria 3–9 Fast spreading; 12 inches<br />

(30 centimeters) high<br />

English ivy Hedera helix 5–9 Excellent spreader; 6 inches<br />

(15 centimeters) high<br />

Sweet violet Viola odorata 6–8 Fragrant; runners; 5 to 8 inches<br />

(12.5 to 20 centimeters) high<br />

environmental protection, the site should be appropriately prepared. The ground should<br />

be cleared, dug up, <strong>and</strong> prepared like a bed. For example, s<strong>and</strong>y soil should receive an<br />

application of organic matter; drainage in clay areas can be improved by using raised<br />

beds for planting. A popular ground cover such as periwinkle (Vinca minor) cannot be<br />

grown in poorly draining soils or soils with a low pH (less than 6.5).<br />

Species such as crown vetch (Coronilla varia), fringe cups (Tellima gr<strong>and</strong>iflora),<br />

<strong>and</strong> mother-of-thyme (Thymus serpyllum) are relatively easy to start from seed. Potted<br />

plants, though expensive, are easier to h<strong>and</strong>le than seed. For low-budget planting, bareroot<br />

stock may be used to establish the ground cover. However, such plants need more<br />

care to be successful. Small shrubs such as creeping juniper (Juniperus horizontalis) may<br />

be planted as bare roots. They must be watered thoroughly after planting <strong>and</strong> mulched to<br />

retain moisture <strong>and</strong> suppress weeds.<br />

Ground covers are seeded on slopes where manual planting is a challenge or a large<br />

area must be planted. Steep slopes (more than 1:1) along roads may be conveniently<br />

seeded by using a hydroseeder or hydromulcher. Seed is mixed in a water slurry, which<br />

may include some fertilizer <strong>and</strong> pumped under high pressure onto the slope. Hydromulching<br />

includes wood cellulose fiber mulch in the slurry.<br />

Potted ground cover plants are planted like other potted plants. The seedling should<br />

be set in the hole no deeper than it was in the pot. Potted cuttings of species such as<br />

English ivy (Hedera helix) <strong>and</strong> periwinkle may be used to establish ground covers.<br />

Cuttings are spaced closer than potted plants.<br />

17.5.2 CARE<br />

Water is critical during early establishment. Seeds, divisions, <strong>and</strong> transplants should not<br />

be allowed to dry. Mulching helps to prevent drying. Plants should not be overwatered.<br />

Fertilizer application of about 10 pounds of 20:10:10 analysis may be applied to promote<br />

growth <strong>and</strong> development. Ground covers spread over the soil surface, <strong>and</strong> thus irrigation<br />

must follow immediately after an application of fertilizer to wash away residue on leaves<br />

<strong>and</strong> prevent fertilizer burn.<br />

Mulching at planting is necessary to control weeds <strong>and</strong> thereby give the ground<br />

cover time to establish. The mulch may have to be renewed annually to keep weeds under<br />

control. If weeds appear, they should be removed. Watering is necessary when a prolonged<br />

dry spell occurs. Fertilizing is not critical unless the soil is particularly poor in<br />

nutrients. S<strong>and</strong>y soils generally need fertilizer supplementation more frequently than<br />

clay soils.<br />

17.5 Choosing a Ground Cover 521

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