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Garden Plan For Clay Soils

Digging with a spade in clay soil

When you walk about your yard on a wet day, do your shoes stick in the mud? Could you make ceramic pots out of the soil in your garden? Odds are you have clay soil, one of the biggest challenges to the home gardener.

Finely textured clay soils are difficult to work up and develop into a good seedbed. If the clay is dry, it tends to be very hard and lumpy. If it is wet, it tends to be very sticky and difficult to manipulate. It seems like a gardener's nightmare.

How To Amend Clay Soils

Clay soils have their attributes — they can hold huge amounts of plant nutrients and they hold onto water really well.

  Add Organic Matter

While it is impossible to alter the texture of a soil, you can increase the soil organic matter, which in turn will change the structure of soil. In gardening, having soil organic matter make up 4-6% of your soil profile is a great goal to strive for; this can be achieved by incorporating compost, green manure, animal manure, and leaf litter.

  Avoid Soil Compaction

The first precaution you will need to take is to baby your clay soil. Clay soil is particularly susceptible to compaction. Compaction will lead to poor drainage and the dreaded clods that gum up tillers and make working clay soil such a pain. In order to avoid compacting the soil, never work the soil while it is wet. As a matter of fact, until your clay soil is corrected, avoid overworking your soil with excessive tilling. Try to avoid walking on the soil whenever possible.

  Mulch

Mulch provides a number of vital services, including maintaining soil temperatures, reducing soil compaction, increasing organic matter, conserving water, and reducing weed pressure. Using mulch helps to maintain the soil structure and supports a diverse ecosystem for micro and macro organisms through the breakdown of mulch over time and the creation of habitat for these organisms. Common mulch materials are bark, straw, compost, grass clippings, leaves, pine needles, or wood chips.

  Cover Crop

Implementing cover cropping into your garden system can improve soil structure, increase organic matter, increase soil aeration, and aid in nutrient cycling. This is especially true if you are experiencing compact clay soils. Planting a cover crop is an effective way to reduce soil erosion by having plants “hold” soil in place via root structure and by holding moisture and slowing water filtration through the soil profile. After the cover cropping cycle is complete, a cover crop can act as a form of green manure when the cover crop is turned over and incorporated into the soil.

  Select Plants That Prefer Clay Soil

Select plants that have a better chance of thriving within clay soil. Great vegetables that don't mind having excess moisture include broccoli, cabbage, cauliflower, beans, and peas. Flowers that do well in clay soils include Aster, Purple Coneflower, Geranium, Heliopsis, Sage, Black-eyed Susan, and Skullcap.

Our Clay Soil Plant Catalog

The table below has 26 plants that are tolerant of clay soils. The list includes both full sun and shade tolerant plants, flowers, grasses, ferns and sedges. This is only a partial list but includes plants that are commonly found at your local native plant nursery.

Bloom Common Name Scientific Name Color Height Light Soil Moisture
EARLY Brome-Like Sedge Carex bromoides Green 1-2' C,L O,W
Creek Sedge Carex amphibola Green 1-2' C,L M,O,W
Pussy Willow Salix discolor White 10-20' L,S,C O,W
Trillium Trillium grandiflorum White,Pink 1-2' C,L,S D,M
Virginia Bluebells Mertensia virginica Blue,Lavender 3' C,L,S M,O
White Dolls Eyes Actaea alba White 1-2' L,C,S M
Canadian Wild Ginger Asarum canadense Red 3-5" C,L O
MID Blue False Indigo Baptisia australis Blue 3-5' C,L,S D,M
Wild Blue Phlox Phlox divaricata Blue 1-2' C,L,S M,O
Pale Purple Coneflower Echinacea pallida Purple 3-5' C,L,S D,M
Wild Iris Iris shrevei Blue 2-3' C,L,S W
MID-LATE Black Cohosh Actaea racemosa White 4-6' C,L,S M,O
Black-Eyed Susan Rudbeckia hirta Yellow 1-3' C,L,S D,M,O
Butterflyweed Asclepias tuberosa Orange 2-3' C,L D,M
Canada Wild Rye Elymus canadensis Straw 4-5' C,L,S D,M,O
Common Milkweed Asclepias syriaca Pink,Lavender 2-4' C,L,S D,M
Lady Fern Athyrium filix-femina Non-flowering 1-3' C,L D,M,O
Prairie Blazing Star Liatris pycnostachya Purple 3-5' C,L,S M,O
Purple Prairie Clover Dalea purpurea Purple 1-2' C,L,S D,M
Rattlesnake Master Eryngium yucciforium White 4' C,L,S D,M
Red Baneberry Actaea rubra White 1-2' C,L,S M,O
Scarlet Beebalm Monarda didyma Red 3-5' C,L.S M,O
LATE Joe Pye Weed Eupatorium purpureum Pink 4-6' C,L,S M
New England Aster Symphyotrichum
novae-angliae
Purple 6' C,L,S M,O
Showy Sunflower Helianthus laetiflorus Purple 6' C,L,S D,M
Stiff Goldenrod Solidago rigida Yellow 3-5' C,L,S D,M

SOIL:  L = Loam      C = Clay      S = Sandy      R = Rocky
MOISTURE:  D = Dry      M = Medium      O = Moist      W = Wet 

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