Edgewood' is situated in the town of Exton, 35 miles west of Philadelphia, in SE Pennsylvania in the NE USA. The garden, which is approximately 1.7 acres in area, is situated just below the ridge-line on the northern side of the Great Valley, 300 feet above the valley floor and 700 feet above sea level. With perfect drainage, a southerly aspect and shelter from the worst of the prevailing winds, the garden is ideally situated to push the hardiness limits of many plants that would traditionally be considered impossible to grow here. The entire garden is enclosed by an 8 feet tall deer fence, including a driveway gate, without which nature's cute treasures would totally destroy the garden. The family's cats take care of the smaller pests. The soil is moderately acid and very rocky in places, with several exposed large boulders. The entire garden is traversed by a 40 degree slope around 400 feet in length and 100ft deep.
The acre at top of the garden is 75 feet above the house, and like most of 'the hill', is native deciduous woodland, mainly comprised of American beech, several oak and hickory species, and tulip trees. Dogwoods (Cornus florida) are abundant, other natives include Rhododendron periclymenoides, Vaccinium species, Arisaema triphyllum and Chimaphila maculata. Although the soil is generally sandy, moisture retention is good and, in a wet winter, seepage can be seen in a number of places at the base of the slope. The fact that the land to the north of the garden is at least 100 feet higher mitigates against rapid drying out. With the exception of the raised beds along the driveway and around the house, none of the soil has been modified.
Exton is n USDA zone 6b, winter minimum temperatures have reached -5ºF (-20ºC); summer maximum is over 100ºF (38ºC). Humidity is generally low from late fall to late spring/early summer but is very high in July and August, often accompanying temperatures in the 90-100ºF (32-38ºC) range. The combination of heat and humidity makes success with many 'alpine' plants impossible. Much of the winter passes without snow cover, a total depth of around 24" falling in a normal winter. However, we have had 66" and less than 3". Ice storms can be as frequent as snow storms, but weather systems come and go very quickly.
The number of days with abundant sunshine is high, generally 4 or 5 a week, making the conditions are excellent for growing 'in character' plants and bulbs. Four well defined seasons is the norm, fall colors are spectacular and the growing season for plants outdoors is very long, generally from late February through December (for some crocus species).Trees and shrubs appreciate the long hot growing season and flower abundantly; particular favorites are deciduous azaleas, redbuds (Cercis), magnolias and dogwoods. Leaf fall is something to behold and provides a couple of weekends hard work each November, but the resulting shredded leaves make a wonderful base for new beds or mulch for existing ones.
The garden provides a wide variety of microhabitats ranging from shady deciduous woodland to deep sand beds in full sun. Some supplemental water is given when conditions demand, via overnight soaking from sprinklers. The only plants in the garden given any artificial protection are Oncocyclus irises whose sand beds are covered with raised sheets of twin-wall polycarbonate between June and mid-September. Two greenhouses are used for propagating plants from seed for introduction into the garden, and for growing a few species, particularly Cyclamen, which are will not succeed outdoors. Deep South trillium species are raised from seed in cold frames which provide protection from the cold in January and February when the plants are emerging.