How to Amend Soil Around Shrubs and Garden Plants

For best results, improve the soil in the entire planting area.

When I go to the garden center, after loading my cart with flowers and bushes, I head straight for the soil aisle to pile on bags of manure, soil conditioner, and all the wonderful things that I believe will make my plants happy. But is amending the soil around garden plants really a good idea? Here’s the scoop on how to – or not to – improve the soil in your garden.

Does Adding Amendments to Soil Really Work?

When I dig into the hard red clay soil in my yard, it’s hard to believe that anything will grow, much less thrive, in such poor conditions. Plants need organic matter, air circulation, and proper drainage, and my soil is lacking in all of the above. So my standard practice has been to dig a hole, sit the new plant in place, and backfill the hole with rich organic matter such as manure or compost, and I felt darn proud of the job, too.

But when we amend the soil right around our plants, what happens? In short, we create a pocket of permeable, well-aerated, nutritious soil, surrounded by a wall of inhospitable native soil. And from what we know about plants and soil ecology, the plant roots (and the water, nutrients, and air) have trouble with boundaries.

Rich soil in a wheelbarrow.

The tiny feeder roots of the plant will resist spreading out beyond the barrier and instead grow inward in a tight circle. Water will quickly be wicked away into the native soil, or worse, will collect in the basin in what’s known as the “bathtub effect.” So we’re left with a tight ball of roots crowded in a pocket of rich soil that’s considerably wetter (or drier) than the surrounding soil. Basically, we’re left with a rootbound potted plant! And an unhappy one, at that.

How to Amend Your Garden Soil

Nowadays, any conversation on this topic tends to dissolve into a hopeless argument between the “do-digs” and the “don’t-digs.” Some believe soil amendments are vital to growing healthy plants, while others believe that if it won’t grow in your native soil, you shouldn’t be planting it. But if you want to grow plants or vegetables, and your native soil is of poor quality, what’s a gardener to do?

Take the time to dig a large hole when planting shrubs.

To keep your plants happy, all it takes is a little more thought, and a little more digging. Follow these tips to help the plants in your garden grow:

  • Choose Plants Wisely: Seek out plants that are well-suited to your native soil. For example, if your soil is clay, don’t try growing coastal plants that are suited for sandy soil. This simple shift will make gardening much easier and ensure that your plants are healthy long after those soil amendments rot away.
  • Improve All Soil: If you’re going to amend your soil, try to amend all of it, rather than just improving the soil right around each plant. Raised beds are a great way to improve the soil for large-scale plantings, or you can till up an entire area and replace or amend all the soil. For annual and perennial beds and lawns, amend the soil about a foot deep.
  • Dig Big Hole: For deeply planted trees and shrubs where all over amendment isn’t possible, dig the largest planting hole you can. I plant shrubs in a hole no less than three feet in diameter, and yes, that’s a lot of digging!
  • Don’t Overdo Amendments: The biggest problem with soil amendment comes from the extreme difference in texture between the amended and native soil. Mix small amounts of amendments into a generous helping of native soil to keep the boundary from being so shocking to the plant roots.

Further Information


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8 Comments on “How to Amend Soil Around Shrubs and Garden Plants”

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  • Official Comment:

    Thomas Boni Says:
    September 6th, 2018 at 9:11 am

    Hi, Rose!
    The Soil Science Society of America has some great information on this topic: “You can add amendments to soil anytime, but the best times for working it into an existing garden are in the spring before planting, and in the fall when putting the garden to bed,” it states.

    That said, for tailored advice, we recommend inviting a Master Gardener to your home to inspect the area.
    Master gardeners train on a range of topics so they can provide advice, at no charge, for people in their area.

    Good luck!

  • Rose Ann Rook Says:
    September 4th, 2018 at 3:17 pm

    I had a reputable local nursery plant a juniper tree early Spring 2018. They do guarantee it for 2 years. I live in the Ozarks and have very poorly draining soil, not red, but grey and heavy, with big red rocks from the owners decades ago. Water just sits on top of the soil or runs off it. I don’t know if they did any soil amendments when they planted the tree, but there is a “brim” around the base. The soil compacts and has run-off when it rains heavily, and dries to like concrete when dry. I noticed inner branches turning brown, called them, and they said it was probably due to heavy rain and heavy soil. Should we get the soil amended, and can we do it ourselves if the nursery won’t?

  • Carola Dryden Says:
    September 24th, 2016 at 7:51 am

    How can I add soil amendment to trees that are already planted and some roots close to the surface. I have clay soil. I am afraid of digging around the trees because I might damage the roots. My trees also seem to be hit every year with brown spots that look like rust. I need to find a way to make them healthier.

  • Jim paknoosh Says:
    April 13th, 2016 at 6:28 pm

    Did learn a lot reading about soil amendment. I also have the same problem of hard clay which is very difficult to dig out and some times mixed with hard rocks big and small. I am going to redig around old fruit trees and use a better soil to improve my fruit trees. I do appereciate Suzanne Kyle comments. I do everything to save and improve my trees.

  • Suzanne Kyle zone 3 Says:
    June 30th, 2015 at 2:03 am

    We have terrible clay soil with embedded crumbled brick from the previous owners. I too planted a serviceberry tree a couple of years ago the way you should not do. Just like others posting here I was not sure what to do. But I had to do something because the serviceberry tree was not doing as well as it should. So I decided to amend the soil around the serviceberry tree in sections about one month apart. I have now done about 2/3 the way around the tree with another 1/3 left which I will do in a month’s time.

    When I started digging it was unbelievable how bad the soil was past the old hole I originally dug. It was like cement and not a single worm anywhere. I took the soil right out up to the drip line of the tree, hoping that I won’t damage too many roots but close enough to minimize the heavy clay belt around the tree. I replaced it with 1/3 plain top soil, 1/3 potting soil and 1/3 composted sheep manure. Into this mixture I added back some of the clay soil I had removed. Perhaps not as much as this article suggests but we’ll see. I can always work in a bit more.

    So I think if the soil is really bad that perhaps removing/amending soil in stages with time in between for rest might be a reasonable way to go? There’s risk for sure, but if the soil is really bad, then there’s an even bigger risk by doing nothing. It comes down to a judgement call. I am no expert by any stretch, but this is my 2-cent’s worth on this topic.

  • Donna Says:
    May 27th, 2015 at 1:55 pm

    I have the same problem as Allen, above, only it’s with a rose bush. I’ve already replaced a bush that died … it’s in a spot the homeowner insists on using for a rose bush, and I want to make it work any way I can. What’s the damage control for a plant that’s already in a hole full of ammended soil sitting in the middle of a desert of clay?? Dig it up? Dig ceramic or gypsum in slowly? Work on the surrounding soil? Help!!

  • Allen Says:
    November 3rd, 2014 at 3:57 pm

    I read the article” How to Amend Soil Around Shrubs and Garden Plants” and realized that I planted a pear tree by removing the heavy clay in my yard and replacing it with Miracle Grow garden soil earlier this year, the exact way this article said NOT to. The tree is currently very healthy but I am now afraid I have doomed my great tree for a terrible future. My knee jerk reaction would be to dig up the tree again and do it right, but I that would probably just make the situation worse. Is there a way to fix this “bathtub effect” problem and save my tree?

  • Rose Behrens Says:
    April 7th, 2012 at 8:31 pm

    I live in Pueblo West Co. and the soil here is very poor, some clay some shale and I want to amend it, I bought some bags of top soil and I also want to add some horse manure but Im not sure in what order to do that. I’ve already dug out about 8 -10 inches of the bad soil and now need to know which to add first……the top soil or the manure. Thank you for any help you can offer.

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How to Amend Soil Around Shrubs and Garden Plants