Roses in Alaska: Soils, pH, and Digging the Hole

Growing a healthy hardy rose starts from the bottom up. A rose has a better chance of warding off harmful pests and disease and surviving an Alaska winter if it's strong and vigorous. The way to help it become strong and vigorous is to let it thrive with a proper foundation.

First, consider your soil. Roses can thrive in a variety of soils. However, sandy soils, made up of large, mineral particles, allow water to pass through too quickly and lack nutrients that roses need. Clay soils are made up mostly of small mineral particles that cling tightly together. They do not allow water to drain quickly, and can drown roots.

Soil with too much clay needs sand. Both sandy soil and clay soil will benefit from adding organic material such as compost, or rotted cow or horse manure.

Most experts start their recommendation for planting roses with instructions to dig a big hole, perhaps two feed deep and 2 feet wide. Roots will extend as wide as the branches, so take a cue from the rose variety you choose as to how wide its hole should be.

Digging a big hole provides a variety of benefits. Roots will grow better in soil that's not compacted. Loosening the soil creates air spaces essential for roots. And it gives gardeners the opportunity to "amend" the soil, adding materials that will help the rose grow.

Soil from the bottom of the hole is less likely to be fertile, but that's where deep roots will need nutrition. After digging out the soil, figure on replacing up to half with organic materials. Roses will also benefit from other amendments. For first-time planting of bare-root roses, a half-cup of alfalfa meal stirred in with a gallon of soil will stimulate growth.

Many Alaska rose gardeners swear by a half-cup of Epsom salts added to the hole for magnesium. Alternatively, a quarter- to a half-cup of Epsom salts can be sprinkled on the top of the soil after the bare-root rose leafs out. Large, established plants can use one cup per plant in the spring.

After planting, wait two weeks before applying fertilizer. An 8-32-16 fertilizer works well. One note of caution, though: some hardy roses do better with little or no fertilizer.

Not everyone will bother, but you can also analyze your soil's acidity and alkalinity. Local nurseries will test soil for a price or sell you a pH kit. Hot tub pH kits also can be used.

Use equal amounts of distilled water and soil, shake up the mixture, let it settle, then drain off and test the water. Acidity is measured in a range from 1 to 14. A pH of 7 is neutral. Anything below 7 is acidic and anything above is alkaline. Roses like soil that's slightly acidic. Ideal pH is 6.8 to 7.1, though roses can tolerate slightly more acidity when the soil is adequately amended with organic material.

© 2002, Alaska Rose Society, All Rights Reserved.
This article was originally published in the Anchorage Daily News, June 14, 2002.

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Last modified: February 02, 2003