Mixed Screens

Prepared by LayLa Burgess, Urban Horticulture Extension Agent, Clemson University, 08/17.

HGIC 1731

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In the landscape, trees and shrubs are often used to create buffers and screens. On occasion, both may be used to frame a desirable view as well. Many plant species used are reliable performers, while others tend to loose popularity as they become unreliable in the landscape due to insect, disease, or cultural problems. The demand for the supply of new plantings perpetuates a constant ebb and flow in the horticultural market.

Leyland Cypress is an example of a plant commonly used as an evergreen screen planting for its uniformity and ability to provide a buffer for privacy, noise control, and as a windbreak. The Leyland Cypress planting model generally consists of using a single type of plant (termed monoculture) where plantings are oriented in one row with close and even spacing.

Leyland Cypress planted as a monoculture screen along a roadway.
Leyland Cypress planted as a monoculture screen along a roadway.
LayLa Burgess, © 2017 HGIC, Clemson Extension

Leyland cypress trees are experiencing severe decline in many landscapes. Trees are being lost one by one, or several at a time in more severe cases because of disease or damaging pests in the monoculture planting system. When the choice of plantings are all the same, disease or insects that cause damage can be easily transferred laterally from plant to plant. However, many other potential factors contribute to plant health and decline such as drought and proper planting technique.

When individual plants in a screen die, it can be difficult to match the lost plant to the existing plantings. It should be possible to locate the same plant species or cultivar, but the once uniform and mature screen becomes dotted with smaller plants. This gives the appearance of being less manicured, less uniform, and may no longer function as an efficient screen. In essence, the once uniform screen is not so uniform anymore. One way to avoid this situation is to plant a mixed screen.

Multiple plant species in a mixed screen provide diversity and safeguard against potential insect and disease problems.
Multiple plant species in a mixed screen provide diversity and safeguard against potential insect and disease problems.
LayLa Burgess, © 2017 HGIC, Clemson Extension

A mixed screen moves away from the straight lined, monoculture design and instead uses groupings and layering of different types of plants. Mixed screens still provide all the functional aspects of privacy, noise control, and protection from prevailing winds, but in addition provide biodiversity to the landscape resulting in a number of benefits to plant health and longevity.

Planning for a Mixed Screen Design

Effect:There are different ways to achieve a mixed screen. Plants can be layered, staggered, placed in groupings (sometimes referred to as clusters), or combinations of these methods to achieve the desired effect. A series of layered plantings generally has the tallest plants located towards the back of the site with progressively smaller layers of plantings in the foreground, though there is some room for variation as in Diagram 1.

Layered planting technique used to create a mixed screen.
Diagram 1. Layered planting technique used to create a mixed screen.

The staggered effect is achieved by placing trees and shrubs in 2-3 successive rows that are offset from one another. Offsetting the rows from each other fills in the gaps between the plants as in Diagram 2.

Staggered planting technique used to create a mixed screen.

Diagram 2. Staggered planting technique used to create a mixed screen.

Clusters of plantings generally consist of installations planted in odd numbered groups of 3, 5, 7 or higher. The grouping maybe situated to block a view, create a noise barrier, or redirect prevailing winds in a particular location as in Diagram 3.

Diagram 3. Grouping or clustered planting technique used to create a mixed screen.

Diagram 3. Grouping or clustered planting technique used to create a mixed screen.

Evergreen vs. Deciduous: Evergreen plants keep their foliage throughout the year, while deciduous plants lose their leaves in the fall and flush out new growth in the spring. When trying to achieve a cohesive screen planting, most often the goal is to block an undesirable element in the landscape. Such elements may include prevailing winds, an undesirable view, excessive noise, intense lighting, or roadway traffic. Depending on the offending element to be screened, evergreen plants may be needed to provide year-round coverage. In this case, the majority of the screen composition can be evergreen, but deciduous trees and shrubs can be intermingled to provide interest as well as biodiversity. When choosing deciduous trees and shrubs, pay attention to the branch form and structure. This will provide winter interest during periods of limited to no foliage. Choose plants that clearly look different in plant form, foliar texture, flowering, or foliage color to enhance the interest of the screen at a distance.

Plant Selection: Tables 1, 2, and 3 provide a selection of evergreen plants commonly used in mixed screen designs for South Carolina. Choose a minimum of 2 types of evergreen conifers, 2 types of broadleaf evergreens, or 2 types of evergreen shrubs for diversity in the landscape.

Table 1. Evergreen Conifers
Common Name
Botanical Name
Height WidthS, W, Both*Hardiness ZoneGrowth Rate
* S= Screen, W= Windbreak, B= Both
Blue Atlas Cedar
Cedrus atlantica ‘Glauca'
40-50'
20-25'
 
S
 
6-9
 
Slow
Deodar Cedar
Cedrus deodara
40-60
20-30
 
S
 
7-9
 
Moderate
Japanese Plum Yew
Cephalotaxus harringtonia
5-10'
5-14'
 
S (shrub)
 
1-10
 
Slow
Cryptomeria (Japanese Cedar)
Cryptomeria japonica
46-60'
20-25'
 
S
 
6-8
 
Moderate to fast
Arizona Cypress
Cupressus arizonica
25-30'
15-20'
 
S
 
6-9
 
Fast
Chinese Juniper
Juniperus chinensis
12'
5-7'
 
S
 
5-9
 
Moderate
Eastern Red Cedar
Juniperus virginiana
30-65'
10-25'
 
Both
 
3-9
 
Moderate to fast
Slash Pine
Pinus elliotii
70-100'
35-50'
 
S
 
7-11
 
Moderate to fast
Austrian Pine
Pinus nigra
40-50'
23-35'
 
Both
 
5-8a
 
Moderate to fast
Loblolly Pine
Pinus taeda
50-80'
30-35'

S
 
6b-9
 
Fast
Japanese Black Pine
Pinus thunbergii
25-30'
20-35'
 
S
 
6-8
 
Moderate
Yew Podocarpus
Podocarpus macrophyllus
15-20'
6-8'
 
S
 
7-11
 
Slow
Degroot’s Spire Arborvitae
Thuja occidentalis ‘Degroot’s Spire’
15’
2’

S
 3-8  
 Moderate
Emerald Arborvitae
Thuja occidentalis 'Emerald'
10-15'
3-4'
 
S
 
3-7
 
Moderate to fast
Green Giant Arborvitae
Thuja plicata 'Green Giant'
50'
12'
 
S
 
6-9
 
Fast

 

Table 2. Broadleaf Evergreens
Common Name
Botanical Name
Height
Width
S, W, Both*Hardiness
Zone
Growth Rate
Loquat
Eriobotrya japonica
15-20'
12-15'
 
S (fruiting)
 
8-10
 
Fast
English Holly
Ilex aquifolium
15-20'
8-12'
 
S
 
6-9
 
Slow
Burford Holly
Ilex cornuta 'Burfordii'
15-25'
15-25'
 
S
 
6b-9
 
Moderate to fast
Needle Point Holly
Ilex cornuta 'Needlepoint'
15'
10-15'
 
S
 
6b-9
 
Moderate
Lusterleaf Holly
Ilex latifolia
20-25'
7-12'
 
S
 
7-9
 
Slow
American Holly
Ilex opaca
15-30'
10-20'
 
S
 
5-9
 
Moderate
Yaupon Holly
Ilex vomitoria
15-25'
15-20'
 
S
 
7-9
 
Moderate
Weeping Yaupon Holly
Ilex vomitoria 'Pendula"
15-30'
8-20'
 
S
 
7-9
 
Slow to moderate
Foster's Holly
Ilex x attenuata 'Fosteri'
15-25'
8-12'
 
S
 
6-9
 
Slow to moderate
Savannah Holly
Ilex x attenuata 'Savannah'
30-45'
10-15'
 
S
 
6-9
 
Moderate to fast
Oak Leaf™ Holly
Ilex x 'Conaf'
15'
8'
 
S
 
6-9
 
Fast
Robin™ Holly
Ilex x 'Conin'
15-20'
12-15'
 
S
 
6-9
 
Fast
Festive™ Holly
Ilex x 'Conive'
10'
8'
 
S
 
6-9
 
Fast
Emily Bruner Holly
Ilex x 'Emily Bruner'
20'
15'
 
S
 
7-9
 
Moderate
Christmas Jewel® Holly PP14,477
Ilex x 'HL10-90'
10'
4-6'
 
S
 
6-9

Slow to moderate
Nellie R. Stevens Holly
Ilex x 'Nellie R. Stevens'
20-30'
10-15'
 
S
 
6-9
 
Moderate
Chinese Fringe-flower
Loropetalum chinense
10-15'
10'
 
S
 
6b-9
 
Fast
Bracken's Brown Beauty Magnolia
Magnolia grandiflora 'Bracken's Brown Beauty
40'
20'
 
S
 
5b-9
 
Moderate to fast
Claudia Wannamaker Magnolia
Magnolia grandiflora 'Claudia Wannamaker'
50-60'
30-40'
 
S
 
7-10
 
Moderate to fast
D. D. Blanchard Magnolia
Magnolia grandiflora ' D.D. Blanchard'
50-70'
30-50'
 
S
 
6-10
 
Slow to moderate
Little Gem Magnolia
Magnolia grandiflora 'Little Gem'
25'
15'
 
S
 
7-9
 
Slow to moderate
Teddy Bear® Magnolia
Magnolia grandiflora 'Southern Charm'
20'
12'
 
S
 
7-9
 
Slow to moderate
Alta® Magnolia
Magnolia grandiflora 'TMGH' PP 11,612
20-25'
8-10'
 
S
 
7-9
 
Slow to moderate
Sweetbay Magnolia
Magnolia virginiana
40-50'
15-25'
 
S
 
5-10a
 
Moderate to fast
Southern Waxmyrtle
Myrica cerifera
15-25'
20-25'
 
S
 
7b-11
 
Moderate
Fragrant Tea Olive
Osmanthus fragrans
15-30'
15-20'
 
S
 
7b-9
 
Moderate
Fortune's Tea Olive
Osmanthus x fortunei
15-20'
8-15'
 
S
 
7-9
 
Moderate
Carolina Cherry Laurel
Prunus carolininana
20-30'
10-15'
 
S
 
7-10
 
Moderate to fast
Live Oak
Quercus virginiana
60-80'
60-120'
 
S
 
7b-10b
 
Slow to moderate


Table 3. Evergreen Shrubs
Common Name
Botanical Name
Height
Width
S, W, Both*Hardiness
Zone
Growth Rate
Glossy Abelia
Abelia x grandiflora
3-6'
3-6'
 
S
 
6-9
 
Moderate
Japanese Aucuba
Aucuba japonica
6-10'
5-8'
 
S (shade)
 
6-10
 
Slow
Japanese Camellia
Camellia japonica
6-12'(25')
6-10'
 
S
 
8-10
 
Moderate
Sasanqua Camellia
Camellia sasanqua
1.5-12'
varies
 
S
 
7-10
 
Moderate
Distylium
Distylium spp.
3-12’
4-8’
 
S
 
7-9
 
Moderate
Fatsia (Japanese Aralia)
Fatsia japonica
5-8'
5-8'
 
S (shade)
 
8-11
 
Moderate
Pineapple Guava
Acca sellowiana (Feijoa sellowiana)
10-15'
10'
 
S (fruiting)
 
8-10
 
Moderate
Inkberry
Ilex glabra
10'
varies
 
S
 
4-9
 
Slow
Meserve Holly
Ilex meserveae
6-7'
3-6'
 
S
 
5-9
 
Moderate
Anise-tree
Illicium spp.
6-10'
4-6'
 
S
 
7-9
 
Moderate
Japanese Privet
Ligustrum japonicum
10'
5-6'
 
S
 
6b-10
 
Fast
Oleander
Nerium oleander
7-12'
6-8'
 
S
 
8b-10
 
Moderate
Japanese Pittosporum
Pittosporum tobira
10-12'
10-12'
 
S
 
8-11
 
Moderate
Evergreen Azalea
Rhododendron spp.
7-8’
varies
 
S
 
6-9
 
Moderate
LeAnn™ Japanese Cleyera
Ternstroemia gymnanthera 'Contherann'
10-12'
6-8'
 
S
 
7-11
 
Moderate to fast
Bronze Beauty™ Japanese Cleyera
Ternstroemia gymnanthera 'Conthery'
6-8'
5-6'
 
S
 
7-11
 
Slow
Awabuki Viburnum
Viburnum awabuki 'Chindo'
12'
8'
 
S
 
7-11
 
Fast
Japanese Viburnum
Viburnum japonicum
6-8'
6-8'
 
S
 
7-9
 
Moderate
Sweet Viburnum
Viburnum odoratissimum
10-20'
12-18'
 
S
 
7-9
 
Moderate
Leatherleaf Viburnum
Viburnum rhytidophyllum
10'
10'
 
S
 
5-8
 
Fast
Laurustinus
Viburnum tinus
6-12'
3-6'
 
S
 
7-11
 
Moderate
Prague Viburnum
Viburnum x pragense
10'
10'
 
S
 
5-9
 
Fast

Spacing: Regardless of the arrangement of plants in the mixed screen, plant spacing should adhere to individual plant size (i.e. height and width) at maturity. Avoid the temptation to install plants too close together to quickly achieve the desired effect. Plants not given adequate space, will eventually outgrow an area leading to crowding or excessive shading. Proper plant spacing provides good air circulation among plantings and lowers the chances of creating an environment that encourages plant disease or other complications such as, root competition for water and nutrients. Denote proximity to roads, sidewalks, driveways, utility lines, or drainage areas in order to avert potential future problems. For more information on planting trees and shrubs, refer to HGIC 1001, Planting Trees Correctly and HGIC 1052, Planting Shrubs Correctly.

Additional Features: Single specimen plants can be strategically placed to provide focal points throughout the mixed screen. Fences made of block, stone, brick, or wood intermingled within or adjacent to the screen can add interest or fill in space while plant materials mature. The placement of sculptures, birdbaths, birdfeeders, or benches can create an inviting feel to the space. However, keep in mind, less is often more.

Precautions: Once the mixed screen layout is determined and plant selections are considered, it is always a good rule of thumb to get a soil test prior to plant purchase. Soil test results provide information on soil pH adjustment, soil amendment recommendations, and fertilization needs. For more information, see HGIC 1652, Soil Testing.

Another important factor to consider is the availability of a consistent source of irrigation. New plantings require adequate water during the establishment phase. Once trees and shrubs become established, they need approximately an inch of water per week to survive and thrive. If installed properly, a drip irrigation system provides consistent irrigation. Irrigation systems may need to be adjusted as the plants grow larger or in times of higher water demand when temperatures increase. Make sure the emitters are not clogged and are working properly by checking the irrigation system periodically. Ground level irrigation encourages good water penetration into the soil at the root zone promoting proper plant health and successful mixed screens. A light layer of mulch will help the plants retain moisture and suppress weeds that often become competitors for nutrients. For more information on irrigation, refer to HGIC 1056, Watering Shrubs & Trees.

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