Digging Deeper: Soil Types

Cacti and Succulents

When we think about gardens, we usually envision the leaves, stems, and flowers of plants, but what about growth below ground? The roots are considered to be the “hidden half” of the plant. They’re essential to the plant’s success, providing anchorage and absorbing water and nutrients from the soil.

This article will walk you through the three main soil categories (clay, silt, and sand) and give insight into what that means for your plants. Not sure what kind of soil you have? Don’t worry; we’ll teach you how to find out.

Clay Soil

Clay particles are small and flat, packing tightly together. However, its small size means it has a larger specific surface area (surface area for a given mass). Overwatering is the biggest challenge gardeners face with heavy clay soils. The best approach is to water deeply and less frequently to prevent waterlogging and encourage root growth. It’s also beneficial to plant slightly above the soil line in poor-draining soil to improve aeration at the crown.

Avoid compaction by not overtilling, walking on garden beds, or using heavy machinery when planting. Also, avoid working the soil when it’s wet.

Since clay already holds onto nutrients well, you can use a light hand when fertilizing.

Suggestions for clay soil: • Low Scape Mound® or

Ground Hug® Aronia (chokeberry) • Kodiak™ series Diervilla • Sugar Shack® Cephalanthus (buttonbush)

Silt Soil

Silt shares similar properties as clay – smaller particle size, small pore spaces, and larger specific surface area. However, the silt particles are slightly larger and irregular in shape, which solves a lot of the problems we see in clay. Silt soil is generally very fertile. Moistureloving plants tend to love growing in silt soils.

Silt has better drainage than clay, but is also highly susceptible to water erosion, as particles that don’t stick together are easily washed away.

If silt soils become compacted, they take on many of the problems we see in clay soils. Be careful when walking on garden beds, using any machinery, and over-tilling when planting to avoid this. To prevent water from pooling on the surface of the ground or washing away, give the soil time to dry between watering. If you’re careful with your silt soils, your plants will be thankful!

Suggestions for silty soil: • Happy Face® series Potentilla (bush cinquefoil) • Sweet Emotion® or Ruby

Anniversary® Abelia • Paraplu® series of Hibiscus (rose of Sharon)

Aronia Low Scape Mound Hydrangea paniculata Limelight Prime

Sandy Soil

Sand particles (or grains) are likely the most familiar, mainly because they are visible to the naked eye and have a coarse texture. Plants that prefer dry soils grow well in sand.

There is great drainage in sandy soils, so you won’t need to worry about overwatering. While this solves the problem of waterlogging, it causes new problems. Sharp drainage means the soil is prone to drought and is infertile. Choose slow-release fertilizers over liquid fertilizers to lower the risk of nutrient leaching.

Encourage deep root growth by watering deeply with less frequency. Roots will “chase” the water and penetrate deeper into the soil profile, helping the plant access deep water and nutrients reserves.

Sandy soils may have some weaknesses, but they’ll still support a wonderful garden if you handle it wisely!

Suggestions for sandy soil: • ‘Miss’® and Lo & Behold® series of Buddleia (butterfly bush) • Limelight Prime® Hydrangea paniculata (panicle hydrangea) • Incrediball® Hydrangea arborescens (smooth hydrangea)

Not Sure What Type of Soil You Have?

The quick and dirty way of finding out is by using your hands. Make a little hole in your garden, approximately 6 inches deep, and grab a chunk of soil. Mix it with a small amount of water in your hand and try to form a ball, then add more water and rub it tight between your fingers.

If you can form a ball easily, it’s likely clay soil. It will feel sticky when wet, especially when you rub it between your fingers.

If you can almost form a ball, but not quite, it’s likely silty soil. When wet, it will feel silky and smooth between your fingers.

If there is no hope of forming a ball, it’s likely sandy soil. When you rub it between your fingers, it feels coarse and grainy.

The type of soil you have will heavily influence plant growth. But when you know what’s happening below ground in your garden, you’ll have some important tools to aid in gardening success.

MIRANDA NIEMIEC Plant Biologist

If you want to know the science behind plants, Miranda is here to help. Proven Winners® ColorChoice® plant biologist and fan of all things flowering, Miranda loves to make gardening and horticulture accessible to the masses. She has traveled all over the world (from Africa to Central America and the UK) researching plant biology and nutrient dynamics and knows just what your plants need to call your garden home.