Portland Nursery

- Garden Amendments

Portland Nursery has a garden amendment for every occasion; whether it’s for planting that new rhododendron, getting a new garden bed ready for vegetables, or mulching around your roses, there are many that are appropriate for your needs.

Amendments are...

Materials that, when added to the existing soil, work to improve its condition and physical properties (increase water retention, drainage, aeration, etc.) making it more beneficial to plant root development and growth.  Amendments may include things like compost, pumice, sand, peat moss, among others. 


is an amendment that can be thoroughly mixed into the existing soil. It can be a blend of organic materials (peat moss, manure, wood ash, for example) and may sometimes include inorganic components (perlite, vermiculite, sand, for example), or a combination of the two.

In the past, manure and peat moss were the standard for compost. Now it has been found that plants benefit with a wider blend of components, but you will find that most composts still include both peat and manure in their mixes. Today there are environmental concerns with some sources of peat, so using smaller quantities in conjunction with other materials still provides its beneficial qualities without relying so heavily on its use.


is not an amendment per se, because it is not mixed into the soil, but rather spread on the surface. It is used to promote water retention, weed suppression and moderating soil temperature (helping to keep cooler in the summer and warmer in the winter). Mulch is also used for an attractive, finished look to garden beds.  

There are two types of materials used for mulch – top dress, or removableis mostly used for weed suppression and winter protection, then removed after it has served its purpose. This type includes larger particle material like straw, leaves and bark products.

Compost and other materials may be used for the second type known as a non-removable mulch and which can be applied at any time of the year. As time passes after application, non-removable mulch is worked into the soil or gradually incorporated by the activity of weather and worms (which then makes it also an amendment) and other soil dwellers. 

Amendment Choices

There are so many choices, we thought we’d give you a guide to the products we carry and the situations for which they’re best suited, to help get you started:


  • Nurseryman’s Bumper Crop
  • Nurseryman’s Black Forest
  • EB Stone Planting Compost


  • EB Stone Rose Planting mix (particularly rich blend)
  • EB Stone Planting Compost
  • Whitney Farms Planting Compost


  • Nurseryman’s Black Forest
  • EB Stone Planting Compost
  • Whitney Farms Planting Compost


  • EB Stone Rose Grow
  • Whitney Farms Rose Planting Mix

New Lawns (by seed)

  • Whitney Farms Seed Cover
  • A thin layer of any non-acidic, fine-particle compost will work, too

Acid-loving plants (Rhododendrons, Azaleas, Blueberries, Camellias)

  • EB Stone Azalea/Camellia Garden Mix

(Note: here in the Pacific Northwest our soil tends toward the acidic, so while a special blend for acid loving plants might not be as necessary as it would elsewhere, you can be assured of giving these plants a boost by giving them amendment suited to their needs.)

For Hard Clay Soil

Nurseryman’s Black Forest, or any other ‘chunky’ (woodier, large-particle) mix

  • Pumice

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