Garden Soil Amendments and Mixes for Water Retention

By: Mike Darcy

stand alone pot

Arm your garden! Amend beds for maximum water retention in preparation for dry summer weather.

With our early spring weather here in the Pacific Northwest, many plants seem to be about two weeks ahead of what we would consider their normal blooming schedule. We have had a season that has been one of the most magnificent for flowering magnolias that I can remember. Roger Gossler from Gossler Farms Nursery in Springfield, Oregon told me that he thought this spring blooming season has been one of the best ever, and Gossler Farms Nursery probably has one of the largest selections of magnolias growing in a private garden in North America.

I mention Magnolias, but they are not the only plants that are either blooming early or have emerged early, like our many herbaceous perennials. Many hostas are in full leaf and looking as they do in May! What does all this mean for gardeners? It means that if we are going to amend our existing soil, the time is now. It is much easier to add garden soil amendment now before our garden beds become covered with foliage that makes it more difficult to actually ‘work’ the soil.

BG Just Coir front

Coir (coconut pith) is one of the best natural amendments for water retention.

Several days ago as I strolled through my garden, I noticed that my Gunnera tinctoria was sending out new stalks. It reminded me that my Gunnera struggled for moisture last year when these plants grow best in moist damp soil. So, I added Black Gold® Just Coir around the base and worked it into the top several inches of soil. Coir is processed coconut pith (coir), which has proven to be an excellent soil amendment for water retention.

Spring is also an excellent time to address hanging baskets and other container plants. Plants in containers tend to dry out much more quickly on a summer day than plants that are in the ground, and the more you are able to amend the soil in spring, the better.

In the many containers that I have in my garden, I always like to add some new potting soil every year. Before planting new flowers, I remove about half of the old soil and add new. My preference for new soil is Black Gold Natural & Organic Potting Soil with RESiLIENCE®. It helps retain moisture and gets plants off to a good start.

For hanging baskets, I have found that they are prone to drying out quickly and sometimes need watering twice a day when the weather is hot and/or there are winds. Black Gold Waterhold Cocoblend Potting Soil or Black Gold Moisture Supreme Container Mix with Resilience are ideal for hanging baskets, especially baskets with fuchsias, which require plenty of moisture.

Gunnera early spring

My Gunnera struggled for moisture last year, so I added Black Gold® Just Coir around the base this spring.

For the garden areas where I have shrubs and trees, the soil around established plants benefit from the addition of a garden compost or mulch. One of my favorite mulch amendments is Black Gold Garden Compost Blend. I work this product into the top several inches of soil each spring. It benefits the soil and plants by adding organic matter, loosening clay, and facilitating better drainage.

The use and availability of water has become a critical concern in many parts of the United States, and the Pacific Northwest is not immune to these concerns. While our rainfall has been about normal, the snowpack in the mountains has been far below what is typically expected. The lack of snowpack means that our reservoirs will not have the reserves they need for the summer months when water use is at its highest. By taking some steps now, we can help reduce our summer garden water requirements and still have a lush garden.

About Mike Darcy


Mike lives and gardens in a suburb of Portland, Oregon where he has resided since 1969. He grew in up Tucson, Arizona where he worked at a small retail nursery during his high school and college years. He received his formal education at the University of Arizona where he was awarded a Bachelor of Science Degree in Horticulture, and though he values his formal education, he values his field-experience more. It is hard to beat the ‘hands on’ experience of actually gardening, visiting gardens, and sharing information with other gardeners. Mike has been involved with gardening communications throughout his adult life. In addition to garden writing, he has done television gardening shows in Portland, and for over 30 years he hosted a Saturday radio talk show in Portland. Now he writes, speaks, gardens and continues to share his love of gardening. To be connected to the gardening industry is a bonus in life for Mike. He has found gardeners to be among the friendliest and most caring, generous people. Consequently, many of his friends he has met through gardening.

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