Mariel Tribby -

Twenty plants for rock gardens in the Midwest

Perennials:

Agastache rupestris - threadleaf giant hyssop

Asclepias tuberosa - butterfly weed

Baptisia australis - blue false indigo

Coreopsis verticillata ‘Grandiflora’ and other cultivars

Echinacea - coneflowers

E. paradoxa - yellow coneflower

E. angustifolia - narrow-leaf coneflower

Heuchera sanguinea - coral bells

Iberis sempervirens - candytuft

Iris - standard dwarf bearded cultivars

Juniperus conferta ‘Blue Pacific’ - shore juniper

Manfreda virginica - American agave

Oenothera macrocarpa - Missouri evening primrose

Phemeranthus calycinus - fameflower

Penstemon cobaea - dew flower 

Penstemon digitalis and cultivars such as ‘Husker Red’ ‘Dark Towers’ - beardtongue

Bulbs

Iris reticulata and cultivars

Narcissus ‘February Gold’, ‘Tete-A-Tete’ and other cultivars of miniature daffodils

Crocus vernus and cultivars - Dutch crocus

Colchicum ‘Poseidon’ and other cultivars - autumn crocus

Allium ‘Millenium’ - ornamental onion

Grasses

Bouteloua gracilis - blue grama

Schizachyrium scoparium ‘The Blues’ - little bluestem

For the brave

Opuntia macrorhiza - prickly-pear

Opuntia humifusa - prickly-pear

St. Louis-area soils are predominantly clay, which can easily compact and have poor drainage. By working in a moderate amount of organic material, as well as coarse sand and pea gravel, soil drainage can be improved. Native plants that are adapted to our clay soils will perform well. 

The heat and humidity of St. Louis summers is punishing. A site with afternoon shade will give plants a respite. Mulching will help to cool the soil, keep down weeds and keep moisture off leaves, an important step to reduce fungal disease caused by high heat and humidity.

Winters in St. Louis are cool to cold, with periods of mild weather. Because the ground goes through freeze and thaw cycles, newer plants with less-developed root systems can be heaved out of the ground. Plant as early as possible in fall to allow for maximum root development and mulch once the ground has cooled to add more protection.

Rain falls throughout the year, with heaviest rainfalls tending to be in the spring and summer. Some of these can be very strong thunderstorms. Snow usually falls from December to February and melts within a week or two.