Giving a bump. I really am interested in answers to this. I have the same problem. Plan to add all the leaves I can to my area this fall and next fall and ...........

No matter what you amend the soil in the planting holes with, the tree's roots are going to invade and choke out the new smaller plant. You dig the hole, fill it with perfect soil, put in your plant, water, and the tree's roots are going to invade. The better you amend the soil, the faster the tree's roots are going to invade.

It is hard to get very many plants to grow in these conditions. For light, an good arborist can thin out some of the upper branches to get more light down to the ground. If you go this route, be careful who you hire. Some tree services are experts at how to cut down trees and keep them from hitting homes and power lines, but they can butcher a tree that you want pruned carefully.

The problem with dry soil at the base of the trees is a much harder problem to solve. The roots from the large trees will soak up every drop of water that hits the ground so that under-story plantings struggle to survive. I've seen two solutions that work well. You can try to simulate a natural woodland floor using mosses and ferns, which can be really pretty once they are established.

I saw an episode of "Gardening by The Yard" where a person had a large tree next to the street where nothing would grow due to dry conditions caused by the tree. The brought in several really pretty pots and placed them around the base of the tree and filled them with shade loving plants. The plants in pots did not have to compete with the tree for water. They had a variety of pot and plant heights that made a really beautiful planting around the base of the tree. Natural looking containers like whiskey barrel halves or hypertufa pots made to look like large hollow stones could both look good under trees.

The mix of trees, poplar vs maple, will make a big difference in what you can get to grow under them. The poplar should not create as big a problem since they are taller with fewer low level limbs, and have deep root systems. The sugar maples will cause more problems since they have a shallow dense root system that will suck all water from the surface soil. They have lots more branches at lower levels to shade out other plants. The roots of sugar maple are somewhat alleopathic. They are not nearly as bad as black walnut at killing competing plants, but their roots do secret a sap that discourages other plants from growing.

If you have some areas that get good sunlight for at least half a day, blueberry plants might work. Blueberries have very shallow root systems, with most of their roots in the top 9 inches of soil. Their roots rarely go further down than 16 inches ever. Since blueberries like really acid soil with a pH of about 5, the other tree's roots won't be as aggressive into these plantings. You could dig a hole 1 foot deep and 2 feet wide, line it with landscape fabric, fill it with peat moss and pine mulch, scatter soil sulfur to acidify the soil, and plant your blueberries. They would need to be irrigated regularly, so a drip system would be needed.

Good luck,
Greg

g'day viviane,

use whatever you can get cheaply enough for amending the hole, if it is the right sort of clay gypsum will help or no use using it maybe? of course the bigger more established trees are gong to invade the new plants area that is how forests work, all you can do is plant appropriate plants, ones that establish a bit quicker and let tham be. if something isn't successful try another variety.

the best thing you can do is mulch the area,that will retain moisture and improve as it breaks down and the worms work it in, mulch heavily app' 10"-20" with a spoilt hay type mulch or even fresh tree lopping chip (app' 6"s for it), keep mulch back from the trunks of the trees about 6+"s.

the mulch will also help with weed control and remulch when needed that might be once a year or twice a year.

len

Here is a link that might be useful: lens garden page

Gypsum can help sodic clay soils and since those are found in the more arid areas of the southwest, not Virginia, it will be of little use for you. That clay soil you have needs lots of organic matter, but peat moss (a non renewable resource) only if there is no other source of organic matter available, and peat moss is very expensive to add to soil. The leaves from the trees around you are a very good source of organic matter.
As a geneeral rule of thumb amending only the planting hole in clay soils can create a "bathtub" where water can accumulate and not flow out because of the change in hte soil, in well amended soils water flows easier then it would in the tightly bound clay soil particles and water always flows along the path of least resistance.

Hmmm. I think I would go for heavy mulch such as wood chips. Tree trimming companies might be willing to dump them on your lot for free. As they break down, their breakdown products modify the soil to make it more friable.

BTW, the American chestnut tree likes dry soil. If you can get one of the blight-resistant hybrids, they will grow like crazy. Check out The American Chestnut Foundation and the American Chestnut Cooperator's Foundation.

The TACF is at the point of cross-breeding its blight-resistant hybrids to local native trees, but since they are based in North Carolina, you should be able to use their base stock as-is - same environment.

Tulip Poplar roots are extremely invasive, and extend far beyond the drip line. They'll invade any moist, rich bed you create and take over.