GARDENING: A Poplar discovery

The native garden is still dormant, the high northern latitude of Ireland results in the spring growing season realistically starting in April, and so there is still good time to explore and acquire dormant plant materials for propagation. The native wildlife gardener is always on the look out for unfamiliar heritage indigenous species to enhance the local ecosystem.
I am looking for the rare tree known as Crann creathach – the shaking tree – Aspen (Populus tremula), a Poplar that tolerates cold conditions. This water loving tree now only exists in small pockets around the country.
Aspen can grow up to 20 metres in height and tends to grow in groups of clones spreading by root suckers – a term for new shots that emerge from the parent root. In fact the largest organism on earth is a 100 acre aspen stand in Utah called Pando. Aspen is easier to identify in autumn with its intense yellow leaves that flutter in the wind. Where it exists Aspen thrives in wet areas along river banks and lakes. Aspen is considered a keystone species supporting large numbers of fungi, lichen, and insects. As a tree it is the favourite food of beaver, an animal where present has significantly reduced flooding of down river towns across Europe.
Locally I have seen Aspen in Pontoon's ancient woodland but I hear from some sources and from the national biodiversity map that it is also exist around the Delphi and Louisburgh area.
Propagating and spreading on this endangered tree in the garden is the objective. It is an attempt to repair and restore unique ecosystem species which we are losing at an alarming rate. Getting permission from the landowner is ideal but sometimes it is unknown who to ask so general principles apply. Never take growing trees unless there are too many, especially rare specimens, from natural ecosystems – the rule is seeds, cuttings or impending destruction specimens only.
It can be difficult to grow Aspen as it is dioecious – meaning the tree is either male or female – and often what looks like a group of aspen trees is just the one clone and so cannot reproduce with itself. If 2 separate trees of opposite sex are present then wind pollinated seeds can be produced. In Scotland where ecosystem recovery is quite advanced, Aspen is being hand pollinated to produce seed.
My previous attempts to grow Aspen from branch cuttings failed – I did not win that time but I did learn. The difference between success and failure is persistence. This season I am going to try root cuttings. This technique is to expose 2cm diameter roots and take a cutting not letting it dry out. One cutting per tree so as not to weaken the tree. The cutting will be covered with compost and left moist, protected from harsh weather in the glasshouse. In a few weeks, fresh green growth should emerge. The entire root can be potted on or if you are brave, each shot can be cut cleanly and potted as a single tree using rooting hormone.
While this is a really rewarding project it would remove significant barriers to ecosystem recovery if our rare heritage trees and herbaceous plants were available to purchase easily from garden centres. I assume economic factors are the main issue here but surely state bodies could rescue these endangered ancient entities and supply to suitable planting locations.
Before I conclude I would like to express the greatest of gratitude to the existing trees of our community that have greatly reduced storm damage to ourselves and our properties some of which perished in this act of storm damage mitigation. Let us plant many more.

Oliver Whyte’s garden, Coill an Chúir at Sandyhill, Westport, is included on the Clew Bay Garden Trail. A chain of beautiful and unique private gardens, the trail opens to the public during summer to raise funds for charity (see www.clewbaygardentrail.ie for more). Each month, an article by a trail member appears in these pages.