Q Why are some trees staked or guyed but not others?
Trees are staked when they need support, perhaps because of their size or the exposure of the site. A tree can also be supported by underground systems that anchor the root into the soil. That is the main aim of support — to keep the rootball of newly planted trees steady in the ground while they spread and develop to anchor the tree firmly.
Before roots have had a chance to establish, a well-developed branch structure means the tree can rock in the wind. This leads to the rootball drying out and working loose. A sudden blast is then all that is needed to topple the tree, assuming it has not already given up and died.
However, you should be aware that wind can also help to strengthen trees — some movement will encourage the development of anchoring roots.
If the tree is put into an excavated planting pit, it will almost certainly need to be supported.
Whips and stock shorter than 1m high where a planting notch is made with a spade probably will not need support. Stakes or canes are also required by many of the tree shelters used to provide a beneficial microclimate.
Q How tall does the stake need to be?
Back in the 1970s, it was common to stake right into the crown. We still see this today. Unfortunately, it provides a leverage point for wind and vandals, and trees tend to snap at the height of the stake.
Forestry Commission research in the 1980s indicated that a short stake — perhaps about one-third up the tree stem — is sufficient to hold the rootball steady. This size also allows a little movement in the upper part of the tree, a factor believed to reduce stem weakening as well as helping to encourage a strong root system.
Stakes are also used to secure tree shelters. The stakes should be long enough for about 30cm to be sunk into the ground — more where soil is light or well cultivated. They should always be below the rim of the shelter or they can cause damage. Use stakes of a larger diameter or thicker canes to secure shelters on windy sites.
Q When should a single stake or two stakes be used?
Single-stake support is usually provided for feathered up to standard trees, and particularly for field-grown stock. In this instance, the stake can be driven firmly into the pit prior to planting and should be in the side subjected to prevailing wind. Double-staking is useful for container-grown trees because the stakes, usually driven into the ground after the tree has been placed in the pit, can straddle the rootball without disturbing it.
Q How often should the tie be checked and adjusted?
It will depend on the type of tie and material used. Some have greater stretch; some need adjusting annually. Follow the manufacturer's recommendations.
Q Underground guying is surely more expensive than staking. Are the benefits of this worth the extra expenditure?
Underground guying systems, such as the Platipus Tree Anchor, should be seen as an investment. They are normally used to support rootballed stock and are installed into the pit at the time of planting. The chief selling point of the Platipus Anchor is that there is nothing above ground to spoil the appearance of the tree — no leverage points for wind or vandals and no trip points sometimes associated with guying methods.
There can also be a time saving. It can be quicker to install some underground guying systems than to set up a double-stake support. Also, if the system used has been designed to rust or rot in the ground, there is no need to check and loosen ties, although inspection visits should
still be made.
Q How should we support large conifers?
Above-ground guying systems tend to be used for cedars, pines and other species that have big evergreen heads. The resulting trip hazard means that guying cannot always be used in public places.