Not your grandma’s garden spade…

April 14, 2014

Air-spade transplanting

Not your grandma’s garden spade…

Air-spading

Roots that encircle the base of a trunk (i.e. girdling roots) can restrict water and nutrient movement and subsequently cause trunk and root decay. An air-spade can be used to expose these problem roots, so they can be removed.

The air-spade has quickly become an important device in the Arnold Arboretum’s toolbox for plant health. Using compressed air to excavate the soil, the air-spade loosens and exposes the delicate root systems of our trees and shrubs without causing significant damage. It’s called into action in a number of scenarios, like investigating potential root issues suggested by above-ground symptoms, breaking-up compacted soil to enhance the movement of water and air, and transplanting mature specimens from one location of our landscape to another.

Air-spade transplanting

Air-spades can be used to transplant full-grown specimens in our landscape. It’s easier to move large plants without the added soil weight, and there is a greater potential to preserve more of the roots with this method. There are some limitations to its use, since not all species respond well to air-spade transplanting and specimens removed from the ground must be quickly replanted to avoid root desiccation.

Typically you may see our horticulturists using the air-spade in the early spring or fall, when root disturbance proves less stressful to plants. During these times of the year, transpiration (loss of water through leaves) is reduced due to lower temperatures and (in the case of deciduous species) the absence of foliage altogether. Roots are also more active in terms of new growth in spring and fall and can quickly recover during these seasons. In addition, soil moisture is typically higher, reducing the likelihood that roots will dry out or need supplemental watering.

The air-spade operates in tandem with a large tow-behind air compressor, donated by the Arnold Arboretum Committee in 2012. This acquisition has allowed horticulture staff to exercise greater flexibility and efficiency in using the air-spade as a part of our standard operations. You can see a video of the air-spade at work in this video, operated by none other than Director Ned Friedman.

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