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Amending soils for perennial beds

Quick facts

  • A well drained, sandy loam soil with plenty of organic material is ideal for perennials.
  • Most soils need amendments for growing perennial flowers.
  • Compost, composted animal manure, peat moss and perlite are all commonly used organic materials.
  • Organic matter increases a sandy soil's ability to hold water and nutrients.
  • Organic matter improves a clay soil's structure, improves drainage and reduces stickiness.

Perennial flower beds can add beauty and value to any landscape. However, perennials don't adapt to poor soil conditions as well as some other plants. Fortunately, because perennials have small root systems, it is possible to amend soil conditions to help perennials thrive.

Tools and equipment

  • Soil test kit.
  • Small trailer for hauling amendment materials (compost, peat, sand, etc.) or have them delivered, depending on how much you need.
  • Non-selective herbicide, such as Roundup, if bed area is infested with weeds and weedy grasses.
  • Sharp spade, sod cutter or Bobcat for removing existing sod.
  • Spade and pitchfork, rototiller or small tractor for digging in amendment materials.
  • Wheelbarrow or garden cart if using the hand-tilled method called double digging.
  • Stakes and string, flour, spray paint or something similar for marking edge of bed.
  • Rake for smoothing soil and removing lumps and rocks.

Site considerations

An ideal soil for growing perennials is loose and easily workable. A sandy-loam soil that is well drained, fertile and has a lot of organic material grows fabulous perennials. This type of soil is uncommon in gardens.

Most soils need amendments for perennials to thrive. Consider the site's drainage, pH, fertility, texture, structure and moisture content at the time you plan to work.

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Adding organic matter

Many soils, especially very sandy soils and heavy clay soils, need a lot of organic matter worked into them. This organic matter makes an ideal soil for perennials.

Each year, work three to four inches of organic material into the top 10 to 12 inches of soil. You can add up to six inches of organic material initially. Do this before planting perennials.

If plants are established, spread the organic material evenly between plants and carefully work in as much as possible. Material left on top works as well as mulch. Worms will help mix more material into the soil.

Apply a nitrogen fertilizer if you use organic materials that will continue to decompose, such as straw, shredded bark, wood chips or fresh sawdust. Microbes need nitrogen to decompose this material.

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Amending clay and sandy soils

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Jennifer Kaczmarski

Reviewed in 2018

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