Shade has a very bad reputation among gardeners and they blame it for the general lack of success they have gardening in wooded areas. Of course, it’s true that you can’t grow just any plant in shade (vegetables, for example, loathe it), but there are in fact lots of plants that will grow perfectly well in shade. I mean plain shade, such as on the north side of a building or under a pergola. Not the shade of trees. Because under trees, the situation is very different.
You see, the real problem of gardening under trees is not so much the shade itself (not if you choose the right plants) as the presence of so many tree roots. These roots dry out the soil, leaving it in a state of perpetual drought, and also deplete most of its minerals while they’re at it. This is called root competition. Some trees (maples, spruces, pines, willows, sweetgums, birches, etc.) are worse than others, with root systems that literally skim the soil surface or even rise above it and really suck all the goodness out. And make digging hell too! But just about any tree, even the so-called deep-rooted ones, is going to have plenty of roots in the top foot (30 cm) of soil. This combination of conditions—shade and root competition—is what is known as dry shade.
No matter how many complaints you may hear about dry shade, it isn’t particularly hard to cope with. You just have to know what to do. Here is my technique:
1. Dig big. You need a big planting hole, as deep as the new plant’s root system and three to four times as wide. The wider the hole, the slower tree roots will be in coming back. So a big hole gives your plant a chance to settle in before the competition arrives.
2. Cut roots if necessary. After all, otherwise you won’t be able to dig at all! You’ll need more than a shovel: pruning shears, a hand saw, maybe an axe. Sure, if you hit a big root, move the hole over a bit and start anew, but otherwise feel free to chop the hell out of any secondary roots you run into. Don’t worry that you’ll be harming the tree. A healthy tree can lose a third of its roots in one year and still be in fine shape. It will simply respond to root pruning by growing abundant new ones.
3. Line the hole with newspaper (7 to 10 sheets). If you have not access to newspaper, used cardboard. Do this for the same reason as point 1 above: to keep the tree roots from moving in before your plant has settled in. Do not use landscape fabric! You want a temporary barrier that will decompose and disappear over time so your plant’s roots can expand. (And landscape fabric will not keep tree roots out for long at any rate: they’re very tenacious!) Make sure you cut off or fold down any part of the newspaper sticking above the ground; otherwise it will act as a wick and dry the soil out further. An added plus is that when a paper or cardboard barrier decomposes, it turns into … compost! So it feeds your plant as it disappears, usually within 12 to 18 months.
4. Plant only plants that tolerate dry shade. Why put in a sun-loving plant like a peony? It will only be miserable. Or a moisture-living plant like an astilbe? It will out-and-out die. Try hostas, epimediums, Solomon’s seals, bigroot geraniums, hellebores, wild gingers, ajugas, even many ferns (many are much more drought resistant than they are given credit for). The list of plants that can tolerate dry shade is surprisingly long! Check out my book, Making the Most of Shade for tons of suggestions.
5. Plant only large, fairly mature plants. This is more important than you think! Young plants, even those that are reputedly tolerant of dry shade, will have a very difficult time settling down in an area that will soon be invaded by tree roots. Even if they do survive, the competition is such that they’ll take forever to reach their full size. But a mature plant, with its large mass of dense roots, will be able to withstand the coming assault. Plus you get that “well-established garden” look right from the start!
6. Backfill with a mix of compost and the original soil, then water well. But you already knew that, so skip on to the next point.
7. Give your plantings extra care the first year. You probably already know that too, but I want to insist on it. Any new plant needs extra care at first and plants that will eventually be drought-stressed by surrounding tree roots, more than most. You don’t need to keep them soaking in water, but do check weekly and water if needed. The old “finger in the soil down to the second joint” method still gives you the best moisture meter ever! If the soil feels moist, don’t water. If it feels dry, do water. And watering is the main care new plants need at this point. Dry shade plants, practically by definition, don’t need particularly good soil or even much fertilizer, but they do need moisture until they are thoroughly established. Then you can bring on the dry conditions and let them grow on their own.
8. Finally, mulch is always good in a dry shade garden. Always!
That’s it! When you apply the right techniques, creating a beautiful garden in dry shade is a cinch.
I garden under maples. Their roots are very shallow and as dense and tangled as steel wool. I made the mistake of using landscaper cloth to separate my plants from the roots and learned the tree roots were even more motivated by the cloth to overtake and strangle my new plants. The newspaper solution sounds like a plan. I want to put in an Edgeworthia. I will be looking for the largest specimen I can find and I will chop the h..ll out of those roots. thanks for the tips.
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Hi there….on the one hand this is reassuring (for the new urban garden I have just got with totally dry (dusty) shade surrounded by old trees). On the other, this flies in the face of everything I’ve read, including university papers, and talking to local greenhouse growers, about what I can do without causing long-term harm to my trees. Basically, they say never cut the tree roots. Only use small starter plants planted between big roots to minimize damage to the trees by digging. And I can’t add soil of any quantity to build beds over tree roots (within the drip line at least…which is about the extent of my garden area) as more than 2 inches or so of soil or mulch will suffocate the roots by depriving them from air and perhaps making it too moist. And that the trees will basically suck so much water the plants will never thrive. All that was here when we bought this place was one spikey yucca, a thorny barberry and some tiny remnants of hosta. Not what I was used to in a wide open space with no trees before. I keep reading that in the short term it will seem fine, but over the years I will be killing the trees. Any further insights about that? Thank you. I am perplexed.
Yes, it gets complicated and you’ll find people with many varying opinions. If you listen to everybody at once, you’ll never be able to garden! However, the school I follow (and what else can I say but it works for me and works for plenty of people) suggests, for example, that you can cut roots (just like you can cut branches). Up to a third of them if you’re careful (although, that’s a lot!). New ones resprout very quickly. You’ll never get anywhere planting small starter plants between big roots: whether you see them or not, you’ll be slicing tree root hairs anyway. Put in big, tough plants and remove moderate roots if they’re in the way. I follow the 8 inch rule for soil: up to 8 inches over the root systems of trees will do no harm (unless the tree is in trouble anyway) and that will allow you to plant. Mulch suffocating plant roots? Since when? I’m talking real, aerated mulch, not something dense and compact. You should see my yard, dominated by huge spruces and how full it has become over the years. The spruces do indeed keep trying to suck all the water and goodness out of the soil – no denying that! – , but I plant forest plants that are used to that. To be honest, I wouldn’t mind if a few of my spruces blew over (imagine all the sunlight I’d gain), but after 26 years of gardening here, no: not one has even fallen. Instead, they just keep getting bigger. And I regularly chop roots, especially when they get under my paving stones and lift them up. No tree should be allowed to risk the health of a visitor (so easy to trip on). Killing healthy trees is really very hard to do. By gardening among their roots, watering more (I know you will), adding mulch (that enriches the soil), fertilizing, etc., you’re actually helping them.
Oh! Thank you! Just found your reply just now! (guess I didn’t check to notify me of comments via email). Thanks so much, I appreciate your experience. AS it turns out, I just consulted another landscaper who is a specialist in using natural/native plantings and she sees no problem in adding some soil and definitely mulch, as long as I am not putting it up to the trunk of the trees or over big exposed roots that have bark (ie holding too much moisture on the exposed roots). And after looking at some of the trees we will do some selective limbing, cutting one big tree down that is crowded by a couple others and not thriving, (and will give the others more space to fill out), and taking down one that is dying off from the top and looks rotten. I am happy to see what you wrote about using bigger plants that will establish more easily as I have plenty that I saved up from my old place that I have kept putting in bigger pots while I tried to figure out what I can get away with. Mostly hostas, and you are not making me optimistic about all the astilbe I have. I have daylilies and heuchera too. There is actually more sun (in the afternoons at least) than I thought there would be, but the fine roots are still all over. Anyway you give me hope. Thank you!
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