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Give Them Room! Spacing Trees Correctly

May 21, 2018

Written by Dave G.

A drive around any older neighborhood will quickly show you giant trees right up against houses, blocking windows, damaging foundations and drains, and making rooms dark and gloomy. Bad decisions about planting distances are easy to find, so why are they made?

The biggest single reason for poor tree placement is the way we see plants as cute and small, and our wish to surround our homes with green. But the consequences, in removal costs, damage, insurance claims, and in the forced cutting down of heritage trees, are serious. Trees take time to grow, and many can and do grow large, so when planting a tree it really is worthwhile to take some time, and use a measure tape, when choosing that planting spot. Don’t get caught out 20 years from now by a hasty choice of tree species, or planting spot.

Remember: Roots Spread Wide

There is a common idea that the roots of trees extend to the ‘drip line’, the place where the foliage ends. The image of the root-system being an upside-down version of the branches is very wrong, because for almost all trees the roots extend 1.5 to 3 times the height of the tree. A sixty-foot tree will therefore have some roots over 150 feet from the trunk, but those outermost roots are small feeding roots – usually not the large structural roots that cause damage.

The depth of roots, on the other hand, is much less than the height, although this is affected by the soil. Deep, sandy soil allows roots to penetrate downwards 10 or 20 feet, but many soils have hard clay or rock just a few feet down, and that effectively prevents deeper rooting – as is seen when a tree blows over in a storm.

Consider What Tree It Is

How far the roots will spread, and how badly they might affect drains and foundations, depends not just on the ultimate height of the tree, but on what kind of tree it is. The most well-known of these aggressive trees is the Weeping Willow, but all willows that grow large can be a problem. Other trees with similar habits include cottonwood, aspen and any other poplar trees, silver maple, Norway maple, black locust and American elm. These trees should be planted 100 feet from any buildings, drain pipes, sewers or swimming pools. Don’t forget to consider your neighbors home and pipes too.

On the other hand, most conifer trees – like spruce, Thuja and pine – have more fibrous, shallow root systems that rarely cause problems. That is why they are popular choices for lawn specimens, hedges and screens. But just because they don’t create damage doesn’t mean they won’t get too big for your garden, and evergreens are especially bad for blocking light.

Think About the Hidden Future Costs

Planting trees too close to a building – your own or your neighbors, or a property line, can end up costing you plenty of money. So can choosing a tree that is too large for your property. The removal of large trees, especially in confined spaces, is expensive. So is ripping out sewer lines and replacing them. If your tree invades your neighbor’s lines, or damage their foundations, you will be left facing the bill for its repair. Tree experts can pin-point, through root examination, exactly which tree is doing the damage, and you may not like what they find. Neighbors can force you to remove a tree that is, or could, be damaging – at your expense.

Tree trimming to remove dangerous over-hanging branches is expensive too and may need to be done regularly. Many people plant large trees, thinking they can leave any problems to future owners, but trees that are, or could become, dangerous problems will reduce the re-sale value, so you do end up paying for your own mistakes.

How Much Room Should I Allow?

With all these considerations, when you are looking for trees to plant, look at the final sizes listed for them and then get out into the garden with a measure, to see how much room you really have, considering all the things we have talked about here. Look at the places you were thinking of planting and consider the following distances.

To protect foundations, sewers and drains, allow the following spacings:

Small trees, such as flowering dogwoods, magnolia, or smaller conifers – allow 10 feet.

Medium-sized trees, such as fruit trees, birch trees, or larger Japanese maple – allow 20 feet

Large-trees, like sugar maple, oaks, Gingko, or flowering pear – allow 30 to 50 feet

Large, aggressive trees like poplars, silver maple or willows – allow 100 feet

Distance From Buildings and Other Trees

There are other factors worth considering when planting near your home, besides protecting foundations. First there is visual scale. A typical two-story home, with a pitched roof is 20 to 25 feet tall. Many trees, evergreen or deciduous, will grow 60 to 80 feet tall, and right alongside your home that is going to look pretty silly. Besides that, overhanging branches can break, causing roof damage, or if the whole tree comes down in a storm it will demolish most of your home. Far better to plant trees that grow no more than 40 feet tall within a 20 feet radius around your home. Keep those larger trees further away, where you can see and admire their beauty, without any risk.

Consider too the width of the tree. As a rule of thumb, if you half the width listed for a mature tree, that should be the minimum distance away from the house – even then the branches will in time touch the windows. So a better rule would be two-thirds of the listed width. That is also a good rule for spacing trees apart, if you want them to retain their individual identity. Trees planted close together make a nice forest, but that may not be the garden style you had in mind!

Think About Light

If you are planting a larger tree, where will the shadow fall? Roughly speaking, a tree will cast a shadow equal to its height by mid-afternoon in mid-summer. That shadow will be to the south-west of the tree. In winter the shadow will be much longer, which is why large evergreens are not good choices near a house. On the south side of your home, a deciduous tree may cast welcome, cooling shade in summer, and let warming sunshine through in winter – a much better choice.

Don’t Be Put Off Planting Trees

All of this doesn’t mean you shouldn’t plant trees – with all the joy and beauty that brings. It does mean you should choose wisely. Today we have many smaller versions of full-size trees available, plus all the trees that stay small naturally. There are many, many good choices available, depending on your circumstances, so plant away – just give some thought before you do it. If you really do want a specimen of a giant redwood in your courtyard garden, there is always bonsai!

Comments 20 comments

  1. April 12, 2020 by Beverley

    Thank you for the guidance provided. I have a Custard Apple tree which was considered a miniature plant without much possibility of growing above 6′ feet tall. It has now grown to ~~20 feet and I am now worried about structural damage as it is now situated one foot from my house (we have expanded the house since it was first planted). I am especially concerned as I live within a townhouse complex (row of five units/block).

    Would it be wise to maintain it in the same location and prune or should I cut it down?

    Thanks for your feedback.

    1. April 12, 2020 by Dave G

      Thanks for the textbook example of faulty planting – but it’s easy to make mistakes like this when you first start gardening!

      Custard Apple doesn’t have an extensive or very vigorous root system, but it can reach 40 feet, so you would be best to take it out now. Plant something else further away if you want to the shade, or another one if you like the fruit. They do tend to break easily, so that’s worth considering too.

  2. April 23, 2020 by Bonnie Hypes

    I have very tall bald cypress trees and the roots are horrible popping up all over the yard not to mention what they are doing to my foundation, we are removing them and roots roots roots and more roots. Can you recommend trees to plant that would be about 20’ from the foundation that won’t have a bad root system? I love magnolias what if I plant that in the front y’all d as a shade tree and another the Jane magnolia between the street and the sidewalk?

    1. April 23, 2020 by Dave G

      20 feet should be fine for any medium-sized tree, except willow or poplar perhaps (or your cypress!) Evergreen magnolia do get pretty large, but one should be fine for decades, especially if you choose a more compact variety. The Jane Magnolia would grow right beside the house if you wanted – the roots are not extensive or big. Fine out by the sidewalk.

  3. April 30, 2020 by Cubi C.

    Thank you for writing this! It’s very helpful.

    I am planning to have a fruit-bearing Tree Planting Birthday party for my son in October. 😁

    Doing my research of what am I gonna need from the land, seedlings and stakes then I saw your article!

    There are really a lot of things to consider. 😊

  4. May 20, 2020 by John M

    Thanks for the great info. Just pointing out one mis-statement: in the section “Think About Light,” you mention “a tree will cast a shadow equal to its height by mid-afternoon in mid-summer. That shadow will be to the south-west of the tree.” In the afternoon, the sun is to the southwest, so a shadow will be cast to the northeast. My sugar maples thankfully remind me of this every sunny summer day:-)

  5. May 21, 2020 by Kamila

    I’d like to plant a shade tree near my driveway to shade the driveway but I’m concerned the roots will damage the driveway. Could you recommend a tree with appropriate roots?

    1. May 21, 2020 by Dave G

      Choose a smaller flowering tree with a dense crown, like a flowering dogwood, or some of the larger crab apples. Or a smaller form of a maple, birch or oak. Avoid larger trees like poplar or ash. All evergreen trees (pine can be a nice shade tree if the lower branches are cleared up) have finer roots that won’t damage foundations or driveways. Whatever you plant, place it more than 6 feet from the drive – put it on the south side to throw a shadow.

  6. May 25, 2020 by Amy Adams

    Do you know of any trees that can be safely planted six feet apart? We are hoping to find some to plant to memorialize our children graduating elementary school in the time of social distancing as a class gift.

    1. May 25, 2020 by Dave G

      That’s a very worthy goal. It sounds like you have limited space, or is the 6 feet symbolic? Perhaps some of the more slender Juniper trees – tough and resilient plants, a suitable metaphor for the circumstances. Plant like Blue Arrow Juniper, or Skyrocket Juniper are all very narrow and upright. If the position is more shaded, then Skypencil Holly could be a good choice – also slim and upright.

  7. June 19, 2020 by Magi N

    I am planning on planting a snowdrift crabapple and a Alaskan Blue Cedar penula in the same area. how far apart should they be?

    1. June 20, 2020 by Dave G

      I think if you follow the ‘rules’ in the article all will be well. Don’t forget that the Cedar needs sun, so don’t plant it where the shadow of the crabapple will shade it once it grows.

  8. August 13, 2020 by John O

    Just came across this really helpful article. Thank you! Our family is looking to fill a blank canvas backyard with trees for shade and privacy, now that we have a new patio. I have a question regarding the two-thirds width rule of thumb. We already have a young 4 ft tall Skyline Honeylocust planted in our backyard, with a young Red Oak on the way. The Honeylocust has a listed mature width of 35 ft (17.5 ft radius), and Red Oak has a mature width of 45 ft (22.5 ft radius). Does the two-thirds rule of thumb mean that the two trees should be planted no closer than about 27 ft apart (2/3 x 17.5 ft + 2/3 x 22.5 ft)? Or does that mean the Red Oak should be planted at least 30 ft (2/3 x 45 ft width) from where the Honeylocust is planted? I guess a few feet, one way or the other, wouldn’t make much of a difference, so I guess I am asking out of curiosity to understand the rule. Thanks!

    1. August 14, 2020 by Dave G

      Thanks – glad you found it helpful. If you have 2 trees the same species, and you plant them twice their radius apart, then they will in theory end up touching. If you look at trees in a large garden, ideally they should have some space around them, hence the idea of using 2/3rd of the radius, twice. So your first calculation is correct. In a larger space, though, sometimes we might clusters 3 or 5 trees closer, to make groves, and then space the groves out more widely. In your case, somewhere between 25 and 30 feet apart sounds good, but what about the overall design of your space? Are you just planning a lawn with trees? Over time those trees created shaded areas beneath them that can become gardens, so you might want to link those to whatever existing beds you have. Sorry, I’m making this too complicated!

  9. This article is so informative! Thank you for teaching us.

    I have two scenarios to ask you about:

    1. I’d like to plant a tall tree about 20 feet from the corner of my three-story condo building (replacing a weed maple that was 5 feet closer and whose branches started scratching my building and the adjacent building). I am thinking a single-trunk birch would be lovely and also narrow enough in the branches. My end goal is to have leaves outside the third floor windows. It will require making a hole for the tree in the corner of the asphalt of a parking area, and will be planted right next to a brick patio. (Asphalt abuts the patio currently.) So, how big a circle of asphalt do I need to remove to fit the birch trunk and allow it to grow over the decades?

    Will the roots lift our brick patio?

    2. In another area, we had juniper trees in a line in order to wall off the neighbor’s trash cans. It is under a large tree and so was too shady…three of four junipers died. I just LOVE boxwood but it also needs full sun, yes? It also grows very slowly from what I understand.

    What would you recommend to replace the junipers, which can grow in a shady spot and form a nice barrier?

    With much gratitude,
    TK

    1. September 3, 2020 by Dave G

      Birch doesn’t have a big root system, so no to significant lifting of the patio. I do wonder if birch will do well with most of the roots covered in asphalt, you might want to go with something more ‘urban’ – what kind of street trees are they using in your town? That can be a good guide – and you can usually find a fastigiate (narrow) version of many trees that will fit a smaller space like yours. As for the hole, the best modern practice is to prepare the ground over a wide area, beneath asphalt,before it is laid but that isn’t going to be an option for you. If you can do a hole 6 feet across that should work pretty well. If the soil is poor, add organic material to it, don’t replace it. There is always a danger of creating a sump, into which water will drain, and kill your tree, if you fill a hole in poor soil with nice, fine, richer soil – you need to keep a fairly uniform drainage pattern.
      As for the Juniper replacement, how about Japanese holly? There are several slender, upright forms that are reasonably fast growing, and look quite a bit like boxwood.

  10. Very good information! Please note my friend planted 5 red oaks and 1 live oak in dallas TX in his backyard like 2 weeks ago
    He set those around 6 ft from fence and 8 ft from each other . Keeping the 20 ft distance from the house
    I told him maybe he planted those too close
    He told me the planter told him that trees will not grow at his max due too close and then will work to give him shadow and privacy
    What do you think? Should I ask him to remove and sell those ?

    1. September 19, 2020 by Dave G

      They will grow into a clump, and yes, they won’t reach their maximum spread when crowded together, but they will certainly grow taller, faster, make a dense screen and throw shade quickly. It is really a matter of what a person wants. Many people sell homes after a few years, and pass on the problem to someone else, but the reason we see so few grand, mature trees around is that the old ways of planting for the future seem to have been forgotten, despite the growth of interest in the environment. Most people are interested in how big a tree will be in 10 years, not 100, so trees that are 30 or 40 years old as constantly being cut down because they were planted with insufficient room. To me that is an enormous loss to the future environment, but many people don’t seem to mind anymore, so it’s a matter of personal choice, in the end.

  11. Hi! Many thanks for the article. I have a row of mature hemlock trees functioning as a privacy border with my neighbor. As they’ve matured, they’ve lost the bottom branches. The branches either were dead or needed trimming due to overgrowing our patio. Therefore, we no longer have the same privacy we once did from them. I’d like to plant some ornamental grasses and limelight hydrangeas.

    I’m concerned about disrupting the hemlocks as I understand that they are sensitive to change. Do you think hydrangeas and ornamental grasses would place too much strain on the hemlocks with respect to changing soil composition and root competition? And, if I can get away with these plantings, how far from the trunk of the trees should I plant?

    Many thanks, in advance,
    Jen

    1. September 26, 2020 by Dave G

      You are right about the hemlocks, so I would plant at least 6 to 8 feet from their trunks – the hydrangeas are a good choice, as I guess there isn’t a lot of sun, and they will grow tall if you prune them up into multi-stem standards, which isn’t hard to do. Not so sure about the grasses, as they need sun, but out in front of the hydrangeas perhaps it is sunny? Choose something that isn’t too tall, and looks best early in the year, before the hydrangeas come into bloom.