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plant spacingPlant Spacing Basics

The only way to know the proper spacing intervals for shrubs is to know the mature size of the plants you are proposing for a site. Space your new plants far enough apart so they can shake hands with the other plants around them. Keep them far enough apart so they don’t get pushy with their neighbors. In difficult situations, you may need to cluster them more closely together for survival and to compete against weeds, but don’t get in a hurry for results and create a stressful, competitive environment for your shrubs.

Here are some rules of thumb.

• For most small annuals and groundcover plants, one foot on center is appropriate.

• Keep most perennials and small ornamental grasses one-and-a-half feet apart.

• Small shrubs should typically be about two-and-a-half feet apart.

• Medium shrubs should be spaced about four feet apart. Larger shrubs should be seven feet apart.

• Tall shrubs should be fifteen feet apart.

• Hedge plants should be four or five feet apart.

• Small trees should have twenty-five-foot spacing.

• Large canopy shade trees need forty feet.

That’s an overly-simplified list, but it is a starting point. Adjust for each species as you learn about them.

It’s okay to break all those rules if you have good reasons. Spacing plants more closely for immediate effect is not a good reason. Attempting to establish an interwoven grove or mass is. Be patient. Plants take just a little time to grow to maturity. It is a shame to not let them fulfil their maximum potential. Plants that are spaced too closely will suffer due to competition for nutrients, water, and sun. Rather than a nice, thick mass of shrubs you end up with a large group of malnourished plants. Good things come to those who wait.

Keep the spacing rules of thumb in mind when you plant near buildings. In this instance, never break the rules. One of the most common, rooky mistakes new landscapers make is locating plant material too close to buildings. Leave room for the plant to grow and more room for maintenance behind the shrubs. Limbs that touch a building provide a bridge for insects to enter. Keep leaves away from gutters. Trees too close to a house will be constantly dropping litter onto a roof that will eventually clog the gutter drains. Move shrubs out from under overhanging eaves that block rain and sunlight. The no-man’s-land close to a building often has construction debris and elevated levels of lime, anyway. Leave plenty of breathing room between a building and foundation plants, or else you might cause damage to the buildings and long-term maintenance issues.

Leave plenty of open vertical space in front of windows. Calculate the maximum mature height of proposed foundation plants and make sure nothing grows to obscure the important features of the building. Another rooky mistake is to design a landscape plan that looks good only on paper or to birds flying overhead. Consider the landscape from every angle, both inside and outside the building. Growing plants that hide windows is like covering the eyes of the building.

Your job as a professional landscaper is not to clothe the building with foliage. It is to compliment the building. You are not decorating a cake or dressing a model. You are designing outdoor space.

Near Buildings

Keep the spacing rules of thumb in mind when you plant near buildings. In this instance, never break the rules. One of the most common, rooky mistakes new landscapers make is locating plant material too close to buildings. Leave room for the plant to grow and more room for maintenance behind the shrubs. Limbs that touch a building provide a bridge for insects to enter. Keep leaves away from gutters. Trees too close to a house will be constantly dropping litter onto a roof that will eventually clog the gutter drains. Move shrubs out from under overhanging eaves that block rain and sunlight. The no-man’s-land close to a building often has construction debris and elevated levels of lime, anyway. Leave plenty of breathing room between a building and foundation plants, or else you might cause damage to the buildings and long-term maintenance issues.

Leave plenty of open vertical space in front of windows. Calculate the maximum mature height of proposed foundation plants and make sure nothing grows to obscure the important features of the building. Another rooky mistake is to design a landscape plan that looks good only on paper or to birds flying overhead. Consider the landscape from every angle, both inside and outside the building. Growing plants that hide windows is like covering the eyes of the building.

Your job as a professional landscaper is not to clothe the building with foliage. It is to compliment the building. You are not decorating a cake or dressing a model. You are designing outdoor space.

In Masses

The scale of everything outdoors is big. Did you ever cut a Christmas tree outdoors? Chances are you were surprised to find how much it grew after you carried it inside! Planting a single shrub all on its own can be fairly underwhelming. Plant shrubs in groups of at least three, five, or seven, so the massed planting can suit outdoor scale. Spatially, landscape features need to have considerable visual mass to fit the scale of trees and sky.

For industrial and corporate landscapes, or for roadside plantings, the need for significant visual mass may require the use of hundreds of shrubs or thousands of flowers. When planting daffodil bulbs along the interstate in my former job, we found a minimum of five thousand bulbs were required to be visible to passing drivers! Keep that in mind when purchasing plants for your landscape. No one is ever sorry they bought too many plants. Planting an insignificant number of shrubs to make an impact on a design is a waste of your time. I have a personal rule for myself to buy at least five of any plant I purchase for my home. For public landscapes, be bold and generous with the number of plants you propose.

Rarely alone

Another reason to purchase plants in groups is to mimic nature. It is true that few plants grow naturally as homogenous crops in a large field, but they are rarely growing alone in solitude. That makes sense. Native plants are propagated by seed or spreading roots. It’s only naturally you would see a small group randomly dotted along a woodland path or in a sunny meadow. Mimicking casual drifts of a single, staggered species in an intentionally unintentional manner looks natural and therefore, pleasing. This kind of grouping looks good on both large and small scales. When you plant pansies, for instance, it looks so much better to cluster similar colors in groups rather than evenly distributing them in a uniform mix. Relax your planting plan designs to make them more beautiful.

Filling in with Annuals

Plants take time to grow. Weeds love to sprout in well-prepared soil. Mulch generously between each newly planted shrub or flower. Keep the mulch at least two inches away from the stems to avoid providing cover for pests and to allow your new plants room to grow in contact with the earth. The wait is not as long as you might imagine when first looking at puny, one-gallon shrubs smothered in mulch. The polka-dotted new landscape soon matures into large sweeps of vegetation.

Your garden may look a bit empty when first planted, and the mulch may hide small plants. One way to fill in open spaces and introduce healthy competing plant material to discourage weeds is to use annuals. Annuals are inexpensive. You can buy entire flats of vigorously growing annuals on the cheap and they will quickly fill open spots. They provide striking seasonal color, too! Since they are annuals, they will die out at the end of the growing season and allow your new plants to expand to a mature size. Each year you will need to use fewer and fewer annuals until the woody plant material reaches peak size. Annuals can be used to fill in the voids for those of us too impatient to wait for results.

Plant Spacing