Alpine Delphiniums
This sunny, southwest-facing garden is awash in color in July and August. It is planted with taller species in the center and gradually shorter species radiating to the sides, ending with mat-forming ground covers, such as Rosy Pussytoes (Antennaria microphylla), that spill over the border rocks and drape down the walls.

Standing about 6 inches shorter than the pink, red and blue McKana's Hybrid Columbines (Aquilegia) are my lovely, native Alpine Delphiniums (Delphinium alpestre). In the wild, this species may stand only 3 inches high. In my garden, fed with alfalfa meal, they usually grow to 18 inches and produce more true blue flowers than in the wild.

Besides Columbines, some of their neighbors are pink Fairy Trumpets (Ipomopsis aggregata), purple Sage (Salvia x superba 'Blue Queen') and nearly black Sweet William (Dianthus barbatus 'Nigricans').

The large, flat stepping stones provide a cool root run for my plants as well as allowing me access to the center of this garden without compacting the soil.

To ensure that the soil around the stepping stones does not dry out, even during rainless periods, I have topped this bed and all the other raised beds with 1/4-inch diameter gravel ("pea" gravel) to a depth of 1/2 inch.

The gravel prevents evaporation of soil water, radiates heat around my plants on chilly mountain nights, slows down the flow of rainwater or hose water to allow the water to soak into the soil, prevents gullying and soil erosion in the planting pockets in the rock wall, keeps the undersides of the plants' leaves clean and free of fungal spores and retards the germination of surface-deposited weed seeds.

Unlike wood chips or bark, a gravel mulch does not rob nitrogen from my plants and it never has to be renewed. When I want to add or remove a plant, I simply push away the gravel mulch with my hand until the task is completed. Then I push the gravel mulch back in place.