Alkaline soil can make gardening efforts difficult for homeowners because many trees, shrubs and flowers won't grow well in non-acidic soil conditions. Alkaline soils also tend to have poor soil structure, making it even tougher to see vegetation grow and thrive. Incorporating organic amendments into alkaline soil can have a limited beneficial effect. Homeowners are advised, however, that many beautiful native plants exist where alkaline soils are common. Using these plants instead of trying to force traditional lawn and garden plants to perform under adverse conditions will result in an attractive outdoor environment. Soils that have a pH of 7.0 or over are defined as being alkaline. These are usually desert soils that are difficult for both essential plant nutrients and water to penetrate. Highly alkaline soils are unable to sustain most forms of vegetative growth although some plants thrive in soils that are only slightly alkaline. Lilacs and asparagus love soils with a pH at or slightly above 7.0.