Screens and Windbreaks       

 Where a windbreak is desired or a year round screen, large evergreens such as pine and spruce (conifers) should be planted.  Consider using conifers (cone bearing trees) on the perimeter of the property to block undesirable views or winds.  Generally such a screen planting would be used to shelter and warm the house by blocking the cold winter winds.  Consider hiding a bad view with a dense evergreen tree while leaving desirable views open.   

This is a topic near and dear to my heart.  I grew up in an urban “subdivision” with neighbors just 20’ away from our patio.  I always thought about how the quality of life in this situation could be so much better with some privacy screening.  Good fences make good neighbors!   Just one or two, or better yet, three evergreen trees strategically planted can make a huge difference in the enjoyment of your back yard.  I’ve even seen hot tubs placed on a patio with no fence or screening of any kind and wide open to the view of  8 or 10 neighboring houses.  Does that make sense?  In fact, what I’m about to tell you regarding screen and windbreak plantings is really just good common sense.

For example, as always, keep it natural.  Don’t plant the trees in straight rows.  This will just set you up for disappointment when one tree dies or grows more slowly than the others.  Trees aren’t bricks.  They are individuals.  Regardless how badly we want them to all grow identically, they will be slightly different.  You should spend a lot of time placing flags in the area to represent the trees.  You might start by standing on your patio or at your kitchen window and place flags to hide the bad views.  Look at your flags from all directions to see that it looks pleasant and natural.  Be sure you are covering the bad views.  Check that no 3 trees are in a straight row.  Large Pines and Spruce should be planted about 15’ apart for best coverage when they mature. 

 There are a couple of exceptions to the “don’t plant trees in a straight line” rule.  It’s a different circumstance when space is limited such as along a fence in a narrow yard or when lining a driveway.  In this case a straight row might make sense.  Just be aware that your trees should be planted at least 12-15 feet from the property line to avoid crowding.  Branches growing across your neighbor’s property belong to your neighbor and might get pruned off.   When planting along a driveway, you need to allow plenty of room for the trees to grow and not crowd the driveway.  Little spruce trees planted 5 feet from the driveway will someday have to be taken down or “limbed up” to allow passage down the drive.  I’d suggest at least 20’ of space between the edge of the driveway and the trunk of any tree.  Shade trees might even be given more room.  Low branched shade trees like willows and pin oak should never be used to line a driveway.  This is a prime example of what I’m talking about when I say you could be planting a “liability”.  Another problem with planting evergreens along a driveway is trapping snow.  A line of evergreens will work just like a snow fence.  This is good if they are planted 150’ from the driveway keeping the snow drift away.  But if your “snow fence” is close to the driveway, that’s where the snow will be also.

Regarding plant selection, it’s a good idea to mix several species to guard against attack by potential insect or disease problems.  Pest problems on plants are usually the result of a specific insect or disease attacking a specific type of tree.  By mixing various species of Pine, Spruce, Fir etc, you will reduce the likelihood of an epidemic destroying your screen planting.  If you are trying to cover a large area, you might even mix in some deciduous trees or shrubs to further enhance your barrier planting.  Shrubs planted on the inside of a screen of evergreens will help with the density in summer as well as adding flower color against the dark green background.

You might also consider mixing the sizes of the trees you are planting.  Think about it.  This would enhance the natural appearance of your planting, while averaging out the cost of the entire project!  One rule of thumb when planting trees is that it takes about 1 year per inch trunk diameter for a newly planted tree to become established and resume growth.  In other words, the larger the tree that’s being transplanted, the longer it will take for it to recover from the transplanting, get its roots established and start to grow again.  In fact, it’s common that a smaller tree will often start to grow sooner and eventually catch up with a larger tree.  This doesn’t mean that seedlings will surpass a larger transplanted tree.  But a 3’ Pine tree might catch up to a 6’ Pine tree planted at the same time after a few years.  It takes about 5 years for a small seedling to grow into a bushy little 3’ tree.  Of course with small seedlings planted out in a large lawn many other problems come into play such as weed competition, lawn mower decapitation and rabbit or rodent damage.

Avoid planting evergreens in low spots!  This is generally true of all plants when planting in heavy clay soil.  Clay soil is “tight” and poorly drained with little air space.  Roots require aeration.  When planted in low areas most plants will be stunted at best but will normally suffer and eventually die.  Of course there are exceptions.  Plants that would normally grow in low swampy areas or stream courses, like willows or swamp cypress, will do well in wet spots.  If done properly, this could be a storm water retention area and result in a nice feature in your garden.  However pines and spruce in screens will require good drainage.  One or two feet of mounding is helpful if the area is flat.  If your screen planting goes through a low spot you’ll notice the trees in that area will not do so well.

Screens and Windbreak review:

            Keep it natural (don’t plant in straight rows)

            Use 15’ spacing

            Mix species (avoid future pest problems)

            Mix in some deciduous plants?

            Mix sizes (save money!)

            Keep windbreaks back from driveways

            Avoid planting in low spots

Private vs. public space

(It’s my yard isn’t it?)

Yes, it’s your yard, but the street side creates an impression to everyone who drives by your house.  It makes a statement about who you are.  What is it they say, “you only get one chance to make a first impression?” Generally speaking, the front of your house is the public area.  You might be interested to know that the tree lawn (that space between a sidewalk and the street), is actually not your property.  This area is normally owned by the city.  Of course it’s yours to maintain but not to plant trees on without the permission of the city.  Most cities want to control what types of trees are planted in the tree lawn since they will ultimately be the ones pruning and caring for those trees.  Cities also prefer uniformity in the types of trees planted along a given street.  They also want to avoid messy or wide trees which might interfere with traffic flow.   

The public area is generally viewed from the street all year round and therefore should be pleasant to look at in every season.  This would require a moderate amount of evergreens for winter color.  Of course evergreens are available in all shapes, sizes, colors and textures.  But even deciduous shrubs and perennials can add winter interest, provided there are a few evergreens for background and companion planting.  Winter interest in deciduous material might come from their structure, winter branch color, persistent fruits or vertical accent.  Dormant ornamental grasses have excellent winter interest.  Don’t prune them to the ground in the fall!!!  Deciduous plants do have a place in the public area and can add interest.  However, the bulk of the flowering plants belong in the private area. 

The back is the private space, although this could vary depending on your specific situation.   In colder climates, the private area is generally not used in the winter.  Of course it’s viewed from the windows of the house and can be very interesting with winter features and visiting wildlife.  But the private area doesn’t need to be as clean and neat with winter green color as the public area.  The back yard should have more summer color, pools or fountains, fragrance and songbirds, all things that relax and entertain the senses in an intimate setting.  This is where you can go wild with annuals and perennials that you enjoy in the summer.  Of course you still need to consider the maintenance required by herbaceous plants such as deadheading and dividing or replanting annually.  Low maintenance is critical to the enjoyment of your outdoor rooms.

 Basic Design Review

Front of house (public area) should be simple and pleasant in all seasons

Strike a balance between summer color and evergreens

Consider the winter appearance

Back (private area) can be more colorful for summer use

Consider fragrance

Attract songbirds?

Climate

Your particular climate and soil will dictate what will succeed in your home garden.  Save yourself a lot of heartache and expense, choose hardy plants for your area.  When I say “hardy”, I’m not just talking about cold hardiness.  I’m referring to the toughness it takes to survive your summer heat, soil, exposure etc.  Don’t just choose plants from pictures in books or what you’ve seen on vacation or planted at a previous home in another climate.   Choose plants that will work for the climate in which you are planting.  Most of the same design principles apply in every climatic region.  It’s just a matter of using the appropriate plants for your area.

Of course there are the major climatic regions of arctic, northern boreal, temperate, subtropical and tropical.  Within those latitudes we also have alpine zones, lowlands, deserts and maritime regions.  These divisions will obviously reflect major differences in the flora and fauna that succeed there.  But within these regions you’ll also find variability in soil, rain and snowfall, sunlight, temperature, humidity, etc. 

 Desert zones are pretty self explanatory.  The plants of this region tolerate heat and dryness well.  Unfortunately retirees from temperate climates move into this region and long for the green grass of home.  It makes more sense to use gravel mulch and cacti in a desert environment.  Of course those retired golfers in the desert require grass fairways, so man finds a way to get it done. 

 Similarly when I see gravel mulch used in our green, eastern temperate region, I wonder what the designer was thinking.  I understand that gravel doesn’t require mowing and the intention is usually to reduce maintenance.  But there’s also the problem of reflected heat under the summer sun on plants that are better adapted to the moist temperate climate.  Too much heat in this case can desiccate the plants and encourage pest problems.  Heat loving groundcovers like Sedum would be a good choice instead of gravel.  This is more environmentally sound since, unlike gravel, plants will perform their magic of producing oxygen, cooling the environment and filtering storm water.

 Alpine zones are more extreme.  I’m sure you’ve heard the weather man talk about Denver weather when it’s 70 degrees one day and they get a foot of snow the next.  The weather in an alpine area can change rapidly with a shift in the wind.  Alpine plants are usually tough, low, durable and cold hardy.  This makes it sound like they’d be excellent selections for our Midwestern climate, but our poorly drained soil would be a problem.  Alpine plants prefer sharp drainage.  They often grow in rock crevices.  They can tolerate dryness and cold but not poor drainage or excessive heat.  Of course we can build an alpine garden in the Midwest by stacking up rocks and planting alpine plants in the cracks and crevices.  An alpine garden can be a nice feature for a small sunny space with relatively little maintenance requirements.

 Continental climates also vary as the wind blows.  While not as extreme as the alpine climate, a continental climate is more variable than a maritime climate.  Without the moderating effect of a large body of water and a generally flat topography, the center of a large continent, such as the American Midwest, will have extremes of weather.  Our weather is extremely hot and dry in the summer, and extremely cold and wet in the winter.  This would appear to be a difficult scenario for living things, which it is!  But of course many plants have adapted to these conditions as well and we have many wonderful plant choices available to us here in the Midwest.

 A more moderate climatic region is the maritime climate.  A maritime climate is influenced by the cooling effects of a large body of water in summer including moisture and humidity in the atmosphere.  A maritime climate in winter is typically warmer with more atmospheric moisture, when the water is not frozen!  It’s hard for most people to understand why they can’t grow Rhododendron, for example, in central Ohio when they grow just fine further north along Lake Erie.  This is because the problem involves much more than just the winter temperatures.  The soil along Lake Erie is typically more sandy and acidic which is preferred by the “ericaceous” plants (an acid loving plant group which are typically broadleaved evergreens including Rhododendron and Azalea).  Another aspect to consider with an ocean side location is the salt in the air requiring salt tolerant plants.  This may also be the case for plantings near a major highway that gets salted in the winter for ice control.

 Now lets get down to your home environment and you’ll find that there are widely varying microclimates even there.  The west and south side of your house is normally much harsher for the heat and drying effects of the summer sun or freezing and thawing in winter.  This freezing and thawing cycle will “heave” small plants right out of the ground.  It will also cause bark splitting on trees and desiccation to broadleaved evergreen shrubs.  Desiccation or drying and burning of foliage will happen in winter when the ground is frozen, preventing water uptake, while the sun and wind are taking moisture from the leaves.  This is not the place for Boxwood, Rhododendrons, Azaleas, Pieris, etc.  These broadleaved evergreens, would much prefer the north or east side of your house.  The north and east exposure is usually more protected from the wind and afternoon sun.  This is the place for tender plants with broad leaves but a bad place for the sun loving, tough, fleshy leafed plants.  Microclimate would also take into account such things as proximity to the air blowing from a heat pump, reflected heat off a wall or window, nearness of water in a fountain or garden pool or just protection from wind and sun from neighboring buildings or trees.

Soil types

 OK, let’s talk about soils.  Soils will vary almost as much as climates.  We’ve got the extremes of beach sand to hard pan clay and everything in between.  Of course there are plants that thrive in each of these extremes but many others which will tolerate neither.  Most plants prefer the happy medium of a well drained sandy loam.  If you live in an area with a sandy loam soil and a maritime climate you are in the minority and you are blessed!  We can’t change our climate, but we can all improve our soil by a few simple steps.

 First of all, most people in a clay soil area are envious of those with sandy soils.  While a sandy soil is easier to dig into, it does have it’s down side.  Sandy soils have better drainage, but will also dry out more quickly in summer.  Sandy soils are typically less fertile requiring additional fertilizer throughout the growing season.  This is particularly true when trying to grow a lawn on sandy soil.

 Clay soil, on the other hand is quite fertile.  The problem with clay is that it’s poorly drained and becomes physically hard packed when dry.  The key to improving a clay soil is to incorporate composted organic matter in the top 6”.  One might think that adding sand to clay would improve it.  Not so!  The farmers say “sand on clay is money thrown away!”  Adding sand to clay actually is a good way to make a rudimentary form of concrete!  Adding compost to clay will break up the hard packed clay particles while raising the area making it better drained.  Mounding is actually a good idea. This topic will be covered under the installation section.

 It is often suggested that you should “test” your soil before planting to see what amendments are needed for each particular crop grown.  This is always a good idea to see where you stand with soil type and fertility.  But the vast majority of landscape plants in the Midwest will thrive in any well drained clay loam.  On the other hand, the “ericaceous” plants, which are generally the broadleaved evergreens, such as boxwood, azalea, holly, etc. prefer a well drained acidic soil.  Other plants requiring acid soils include the blue hydrangeas and blueberries.  To grow acid loving plants, folks in a heavy clay area will have to improve their soil by raising the beds and incorporating acidifying amendments such as sphagnum peat moss and acidifying fertilizer.  Periodic top dressing with sulphur compounds such as ammonium sulphate will maintain a low pH and keep ericaceous plants green.