Answer: One of my favorites is periwinkle or vinca minor. This is an evergreen, does not climb, and produces lovely blue flowers in the spring. You could also use the traditional evergreen Hedera helix or English ivy, although it would need to be kept from climbing the trees. There are some newer varieties of this with patterned foliage, so it need not be a carpet of plain green. If the soil is somewhat acidic, you could consider pachysandra as well, this makes the visually smoothest carpet of the three and is also evergreen.
All of these are available as relatively inexpensive starter plants in small peat pots (remove these or at least make sure the entire pot is buried at planting because they can wick moisutre away from the roots if exposed to the air) or small containers in the spring. You may need to special order or reserve some through a local nursery if you need a huge quantity.
Set them between one and two feet apart, closer will provide faster coverage but the wider spacing is adequate also. Mulch the area between the plants to keep weeds down and to help conserve moisture during the establishment period. You will also need to water them until they become well rooted. Eventually, they should be extremely low maintenance and require little care beyond a light raking to remove any thick, heavy leaf cover in the fall.
Good luck with your ground cover!
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