I live in climate zone 7a in New Mexico, and I planted a pear tree in my backyard three days ago. Following the directions on the tag, I dug a hole twice the diameter and depth of the root ball and filled it with potting soil, topping it off with purchased topsoil with fertilizer in it and cedar mulch, figuring this was sensible advice because we have really bad soil here that very little grows in without heavy amendment.

Now I'm reading online that you should fill the hole mostly with native soil, to train the roots to grow beyond the hole you dug. Did I do the wrong thing? And if so, is it too late to dig out the potting soil and replace it with native soil?

up vote 6 down vote accepted

No, it's not too late to 'unplant' it, it won't yet have started to put out roots from the pot shaped rootball. The best way when planting a tree is to prepare the ground beforehand by digging it over in as wide an area as possible and adding humus rich material (garden compost, composted animal manure, whatever you can get hold of), then letting it settle for about 10 days, then digging your hole and actually planting, at which point, you won't be including anything in the planting hole other than fertilizer, and then only if it's spring or early summer.

Given you've got the tree already, and haven't prepared the ground, the best thing to do is unplant it, put it back in the pot in which it came, remove the potting compost and new topsoil as far as possible, dig the area over again, preferably bigger than twice the size of the rootball, this time including something decent as mentioned above rather than potting compost, walk heavily on the area on your heels to compress it and get out air pockets, then dig your hole and plant your tree. Rake up the area you've walked on around the tree so there's loose soil on the top, not solid, compressed ground. If you haven't any garden compost or humus rich materials available, you have time to go and get some before you dig up and replant the tree, it'll be fine as it is for a few days, you'll still be able to do it.

  • I agree, good overall info – J. Musser Sep 27 '14 at 17:10
  • Thanks very much! I'll replant the tree following your advice. – iLikeDirt Sep 27 '14 at 21:55

I agree with Bamboo. It's still safe to replant. There are a few reasons why you should.

  1. Like you mentioned in the question, the tree will grow through the potting soil more easily, and will often treat the walls of the hole as boundaries. This won't let it reach it's full potential.

  2. There are drainage issues involved. If you replace a void in heavy clay or other very poor soil with almost pure organic matter, it will soak up water and tend to get very waterlogged. It won't drain properly into the completely different surrounding soil. This may not be a problem, though, in New Mexico.

  3. The tree will often have a poor anchorage and the roots will be prone to wind damage. Potting soil never firms well, and if the tree doesn't grow roots into the surrounding soil, this will be a problem.

  4. In potting soil, the tree will need fertilizer a lot more. Potting soil doesn't naturally contain any fertilizer, and barely any minerals (available in the surrounding subsoil). Especially peat-based mixes are notorious for 'running dry' on fertilizer far too quickly.

The more time, energy, and materials you put into the hole (properly) the better the tree will do. The saying, "1 dollar tree, ten dollar hole" is good, unless you get a big 30 dollar tree. Then you have to dig a 300 dollar hole :). Follow Bamboo's instructions on digging the new hole. The bigger you make it the better, and you can add a good bit of compost. Be careful in fertilizing, though. I can't tell you how many dead trees I've looked at, and once dug up, the soil was full of fertilizer that's all I could smell. And they claimed to have followed the instructions. I use less, or none, when planting a new tree, and simply top-dress once the tree catches on.

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