Gardening Help FAQs

Here are answers to some of the most common questions we receive about garden plants. You will find concise information on general gardening techniques as well as plant selection and care. For detailed information on specific plant pests and problems refer to our Common Garden Pests and Problems page.

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Horticulture Questions and Answers

How to I create a rock garden?

Gardeners who greatly enjoy growing a wide variety of plants are the best advocates of rock gardens. This type of garden can contain a mixture of evergreens, deciduous shrubs, bulbs, perennials and annuals. Collectively, the design they create is a myriad of color, form and texture.

Rocks, purchased or on-hand should provide the basic framework of the design. The best arrangement will look as if nature had a hand in it's creation. Observation of natural outcroppings along highways and hillsides can be copied on a miniature scale. Group small rocks together to give the impression of larger masses worn away by time and weathering. Medium stones should be used in groups of 2 or 3. Bury large boulders halfway in the ground for stability. Cohesiveness is best achieved by using only one kind of rock in the garden. Limestone and sandstone are the 2 kinds most available in this area.

The soil in a rock garden should be well drained with only a moderate amount of humus or compost. Most rock garden plants do not like rich soil or heavy fertilization. Well rotted manure, worked around the crown of the plant in early spring, is sufficient feeding for the growing season. Also, good rock garden plants are drought resistant making them choice candidates for hard-to-water areas such as slopes and shallow ground. Water deeply and allow soil to dry thoroughly. Watering is most efficiently done in early morning or evening. Rocks hold moisture and release it slowly. Crevices around them provide planting spaces for those plants requiring more than the average amount of moisture.

Mulching helps to control weeds and keeps the soil cooler. Mulched beds reduce water splashing on the plants lessening the chance of fungal problems during hot muggy days and nights. Rock gardens are traditionally thought of as positioned on a slope in full sun. An East or West exposure can provide a respite from all day sun which most plants appreciate.

Some reliable plants for the rock garden include the evergreens and conifers which come in many shades of green, blue and yellow. Juniperus squamata 'Blue Star' has bright blue dense foliage all year. Typically grows to only about 1 foot tall after 5 years, but eventually matures over time to 2-3' high and 3-4' wide. Pinus strobus 'Nana' (Dwarf White Pine) is an irregular globe of soft green needles growing to about 3 feet high with an ultimate spread of 6 feet. Thuja occidentalis 'Tom Thumb' (Dwarf American Arborvitae) has flattened green foliage. This tight little globe achieves a mature height of 14 inches by 12 inches wide.

Deciduous shrubs have a dual purpose. They give us lovely flowers and their twiggy appearance in winter provides variety in texture. Spiraea japonica 'Alpina' grows to only 14 inches high with a profusion of pink flowers in late spring. Deutzia crenata 'Nikko' gently sprawls over the ground barely achieving 1 feet high. This little gem is covered with white flowers in early spring.

Also try some perennials. Anemone pulsatilla (Pasque flower) is one of the earliest bloomers. This plant produces ferny foliage with purple, red or white flowers. The foliage stays nice all summer. Geranium sanguineum (Hardy Geranium) develops a spreading mound of finely cut leaves with many bright pink flowers in mid- spring. The foliage will turn red in autumn. Herniaria glabra (Rupturewort) makes a great ground cover. Good between stepping stones, the dark green tiny leaves will become topped with white flowers in early spring. Oenothera missouriensis (Missouri Primrose) is a sprawling native glade plant which provides night blooming sulfur-yellow flowers all summer.

Add small bulbs such as anemones, snowdrops, scilla and grape hyacinths. Miniature narcissus and botanical tulips return reliably each year and complete the bulb collection. Annuals of small stature such as pinks, ageratum and verbena give the summer season a color boost.

The extensive array of plants to choose from for rock gardens truly offer the opportunity to satisfy the palette of every gardener.