General Discussion:

Spruce Roots & GroundCovers

Messages posted to thread:

Anne14-Aug-01 12:27 AM EST 6   
Susan14-Aug-01 07:47 AM EST 6a   
Dawn14-Aug-01 10:21 AM EST   
Dawn14-Aug-01 10:23 AM EST 3a   
Anne17-Aug-01 09:20 PM EST 6   
Betty18-Aug-01 02:23 PM EST 5a   
Susan18-Aug-01 02:55 PM EST 6a   
Northern Gardener21-Aug-01 03:31 PM EST 3   

Subject: Spruce Roots & GroundCovers
From: Anne
Zone: 6
Date: 14-Aug-01 12:27 AM EST

Hi, we have a couple of large, mature spruce trees about 15ft from our front door, and the roots are now creeping up through the grass, which I understand they are prone to doing. The girth of the trees has changed our traffic pattern so we now walk beside the tree, rather than on the (nearing replacement age) concrete walkway. I was wondering:

1) I'm fine with the grass not growing, but would like some other kind of walk-on-able, shade-liking ground cover to reduce the "mud" factor. Any suggestions?

2) Are we likely to have problems with the roots close to the house?

3) Eventually, we will replace the walkway. Are paving stones realistic? or will the roots push them around?

The trees are an important "good neighbour" policy, and I don't even want to think about removing\trimming them at the present. Any suggestions welcome! Thanks


Subject: RE: Spruce Roots & GroundCovers
From: Susan
Zone: 6a
Date: 14-Aug-01 07:47 AM EST

Triming them a bit by removing some of the bottom branches won't hurt them and can help them look tidier and make it a little easier to garden/maintain the area around them. I have a huge old Blue Spruce on my front lawn. This spring I had the branches removed from the bottom 5 feet or so so it's possible to work under there but doesn't spoil the shape of the tree. I've been experimenting with what will grow under it. I put down soaker hoses to provide water since it is so dry and I added compost and dug it in to help with moisture retention, add organic matter and break up the dense clay soil. So far, the most successful plants I planted are Beacon Silver Lamium and Polygonum affine 'Dimity, (a form of Knotweed). Artemisia 'Silver Mound' is also doing quite well. None of these will take heavy foot traffic but they might help improve the look of under the tree and will grow where the grass doesn't.

I'm not a big fan of paving stones. If the roots don't lift them, freeze/thaw cyles will as the ground moves. Stick with concrete would be my advice.

Re the roots - I don't think they're quite as bad as a willow, but any tree roots can block weeping tiles and eventually work their way into cracks in foundation walls. If you're concerned, try having your weeping tiles inspected for blockage. We just bought this house two years ago and did an extensive renovation and addition. During that process, we found that quite a lot of the original weeping tile was blocked by tree roots and needed to be dug up and replaced, an expensive process...

Subject: RE: Spruce Roots & GroundCovers
From: Dawn
Date: 14-Aug-01 10:21 AM EST

Subject: RE: Spruce Roots & GroundCovers
From: Dawn
Zone: 3a
Date: 14-Aug-01 10:23 AM EST

I have Goatsfoot growing under mine. It grows a little slower under the evergreens than it does out in full sun, but has survived two winters.

Subject: RE: Spruce Roots & GroundCovers
From: Anne
Zone: 6
Date: 17-Aug-01 09:20 PM EST

Thanks Susan & Dawn for your suggestions. As it's the bottom 5 feet of the trees which are so important for privacy in our city lot, I'm trying to avoid snipping them.

I'm not particularly concerned about the grass directly under the branches, it's the 5-10feet beyond them that I'm wondering about.

I don't think I'll be able to dig to amend the soil, so if I add a 6-8" layer on top(possibly with a wooden frame around), will the roots just try to get to the surface?

Also, does anyone have any suggestions for walk-on-able greenery with shallow roots that likes a rather acidic environment?

Thanks, Anne

Subject: RE: Spruce Roots & GroundCovers
From: Betty
Zone: 5a
Date: 18-Aug-01 02:23 PM EST

I have acid soil and have creeping thyme, wooly thyme, and stonecrop sedum in abundance. It takes on a slightly squished look when walked on repeatedly, but can withstand a large amount of traffic. I have a spruce hedge that I have sunflowers growing in front of. The hedge is about 3-4 feet tall but those roots seem to go wherever they want to. I find I can not dig that area up as too many roots in the way but adding soil does not seem to bother them. I am not sure how mature trees would fare.

Subject: RE: Spruce Roots & GroundCovers
From: Susan
Zone: 6a
Date: 18-Aug-01 02:55 PM EST

Betty's suggestion of the thymes is a good one since you're not concerned with planting directly under the tree so there should be enough light for the thymes. A neighbour of mine has wooly thyme in a large area near a tree. It takes foot traffic quite well and looks very nice. I've never had a nice sunny spot for creeping thymes but I've seen pictures of some amazingly beautiful thyme walks and lawns. If you have the right conditions for that, go for it!

Why not try the lamium directly under the tree where it will still grow in dense shade and dry conditions and use wooly/creeping thyme on the outer edges where you want to walk on it? A variegated lamium like "Beacon Silver' does an amazingly good job of growing in the most awful, dark, dry conditions and the leaves are almost luminous and really 'light up' dark areas that would otherwise be barren. It spreads quite quickly and you might have to periodically remove bits that might encroach on the thyme. I don't find it that much trouble - it forms mats that are pretty easy to remove in large hunks...

Adding soil on top of tree roots can be a problem if it is too thick and dense - it can smother the roots. Having said that, I must say, I do it anyway! I make sure it's a light, loose soil with lots of peat and other organic matter. I keep it in a thin layer of an inch or two within the skirt of the tree, tapering to a few inches at the edge or outside of the skirt. I find that the soil frequently forms a cone shape around trees naturally with the high area at the trunk, then sloping away. So the soil I add keeps the cone shape but levels it off a bit.

Subject: RE: Spruce Roots & GroundCovers
From: Northern Gardener
Zone: 3
Date: 21-Aug-01 03:31 PM EST

Anne: Some of our spruce trees are over 45 yrs old & we wish previous owners had NOT pruned-off the graceful lower branches of these trees! Now we have reduced privacy, a wind-tunnel has been created which affects the entire yard, our 'natural' backdrop is bare trunk & the area within the dripline is constantly a major concern. Had the lower branches been left on, they would have cascaded gracefully, majestically to the ground creating a perfect, full, dense, natural backdrop for other trees, shrubs, & perennials. It's much easier to plant or landscape outside the dripline of evergreens than within it.

These trees are not meant to be pruned-up. Leaving the lower branches actually helps to protect the root system (as well as increasing your privacy & the overall look). Removing lower branches does not encourage bushiness or new branches. Little, if anything, grows under them anyway as the trees are heavy feeders & drinkers. Needle drop, which occurs heavily within the dripline, leaves the dry, nutrient-deprived soil very acidic...conditions not liked by many plants. Leave the branches & let nature look after this for you.

You can always create planting pockets between the major roots, if you can dig through their dense secondary roots. Care MUST be taken when adding/increasing soil levels around trees...too much causes suffocation by reducing the amount of air available to the roots; too high up the trunk causes this also along with creating the ideal environment for insects, rot & diseases....means bigger problems. MAXIMUM recommendation for increasing soil elevation around any kind of tree is 1/4 to 1/2 INCH per YEAR!...and only if absolutely required. Ask any reputable garden centre how many times they see trees killed because of being planted too deeply.

Well roots be a problem? Probably. Most people plant very young, little trees (Johnny's grade 1 tree) too close to buildings (or other plants) because of lack of considering mature size.

Will roots come through a raised 6-8" planter around them? Probably, in search of air. Instead of a raised planter, consider using plants of various heights, flower colour, leaf colour & texture to create an inviting bed. Your walkway could even go through part of it or along an edge.

The walkway: uneveness occurs even without any trees or shrubs. Cause: improper base preparation or installation. Proper base installation means 4-5" of solidly tamped roadcrush on top of clay topped with 2" of sand. A layer of super-thick landscape blocking fabric between soil & roadcrush will help discourage, but not guarantee, the roots from coming through. Having said that, I can also attest that roots have been known to lift & shift even a solid, poured concrete walk (in another home). That walkway was roughly 15 feet from tree-trunk. I would allow a space of at least 6-8 feet from MATURE dripline to any walkway, if possible.

How about a curved slate, flagstone or steeping stone walk with Betty's suggested plants growing in between them? 'Steppable' plants are always so inviting! Who says a walkway has to a solid length of brick or whatever material? Lightly pruning the tips of spruce trees every 3 yrs will help control branch spread (but not root spread) & encourage bushiness.

Be careful when amending or adding soil. Consider what your soil composition already is & the needs of plants chosen. Some plants thrive in the acidicity created by adding peat, others will die. Here in central Alberta, we have heavy clay soils. Kelowna & area, coarse sand. Vancouver, very light, peat-like soil. Resource a trustworthy local nursery or garden centre for this.

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