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Lime is used to raise the pH level of acidic soils, making it "sweeter," or more alkaline. Lime-loving trees and shrubs are simply those that thrive in alkaline soils. Alkaline soils are common in the dry regions of the Southwest, Rocky Mountains and parts of the Midwest. While acidic soils can be modified through the addition of lime, lowering the pH level of alkaline soils is often more difficult. Many plants develop iron chlorosis, or yellowing leaves, when planted in these soils. The best solution is to choose plants naturally adapted to alkaline soils.
Many oak and maple species prefer acidic soil and don't grow well in alkaline soils. Two exceptions are bur oak (Quercus macrocarpa) and silver maple (Acer saccharinum). Silver maple is fast growing, but prone to weak wood. Bur oak grows more slowly, but tolerates drought and lives for many years. Honeylocust (Gleditsia triacanthos inermis) tolerates lime soils, grows quickly and provides filtered shade. Its small leaves are difficult to rake up and create a nuisance in the fall. Plant honeylocust away from entryways, where the leaves are easily tracked into the house.
Choke cherry (Gleditsia triacanthos inermis) is a small tree, native to the Rocky Mountain area and adapted to lime soils. It produces white flowers in spring and small, tart fruit used for syrups and jams. Buckeye (Aesculus glabra) is known for brilliant fall foliage and its attractive palmate leaves. Both trees grow 20 to 40 feet high.
Many shrubs tolerate alkaline soils, including lilacs, potentilla, barberry, spiraea, cotoneaster and viburnum. Select lilacs (Syringa vulgaris) and viburnum (Viburnum spp.) for large, flowering shrubs that grow 8 to 20 feet high. Smaller shrubs include spiraea (Spirea spp.), bush cinquefoil or potentilla (Potentilla fruticosa) and cotoneaster (Cotoneaster lucidus). These shrubs stay under 6 feet high. Most hydrangeas prefer slightly acidic soil, but hydrangea paniculata and hydrangea arborescens tolerate alkaline soil.
When selecting plants for lime soil, consider cold hardiness, growing conditions and plant size and use, as well as adaptability to alkaline soils. Select plants adapted to the amount of sunlight and moisture naturally found in your garden. Give plants ample space to reach their mature size.
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