How to plant a tree – As arborists we are predominantly concerned with the care of trees once they have grown; the majority of phone calls we receive are requests to prune or remove trees. We rarely get to be involved in the most important part of an urban tree’s life cycle which is planting. If the right tree, is planted in the right place, in the right way, the need for pruning or removal is significantly reduced and may never be needed. This blog will offer some advice for anyone wishing to plant tree so that it is given the best start in life and has every chance of surviving into the future.
The first step to how to plant a tree would be to select and assess your site.
It may be that you only have one site in question and you just have to work with what you have. If you do have a few options select the sight that has free space, good drainage, adequate sunlight, has some form of shelter from the wind, and has the best soil. If any of these factors are not ideal steps can be taken to mediate against them, but it is much easier and more likely to be successful if the site offers them already. Also refer to https://www.treecareauckland.co.nz/is-my-tree-protected/
Next, access what kind of soil you have to plant a tree.
Sandy soil is free draining but lacks nutrients so you may need to add compost. Clay soil is prone to waterlogging and has nutrients but they are bound up, so you may need to dig sand through it. If your soil is very light in colour and crumbly it may be lacking in nutrients, mixing well rotted compost through will help. If your soil looks dark, is slightly moist, and has earthworms you have hit the jackpot and it should be suitable for a wide range of plants. If you do have to make improvements to the soil do it to a wide an area as possible. As the tree grows the roots will extend far out from the planting hole and will need good soil wherever they go.
These first two pieces of information will help you decide on the tree. Certain trees thrive in specific soil types; others are all-rounders and will make do. The internet is full on advice for this and a good website to start with is http://www.thompson-morgan.com/plants-for-soil-types
You also need to consider the function of the tree; is it for shade? or screening? for appearance? for flowers? for foliage? for wildlife? Once you know the answers to these questions start looking in a plant book or in an online directory for trees that match your requirements. If possible, it is always good to plant native species; they are well adapted to local environments, provide food and shelter for wildlife, and cause fewer problems as they mature.
Once you have decided on a tree imagine it fully grown in the site you have selected.
Information about eventual heights can be found online, in books or at nurseries. Will the tree fit in the space? What will it be shading? This process can help you decide the most suitable tree for your site.
Finally comes the fun part of getting the tree in the ground. First dig your planting pit. It needs to be large enough to accommodate all the roots and any soil that is attached to them. Make any preparations to the soil at this stage. If you are looking to add nutrients to the soil use well-rotted compost, this will release nutrients and a rate that will be more in line with absorption of the plant. Plant the tree to a depth of “nursery line”, this means that the height the soil reached up the trunk after the tree is planted should be the same as when it was growing in the nursery. For root balled or container grown trees this will be obvious, for bare root trees you should see a line just above where the roots start growing.
Once the tree is in the pit to the right depth back fill with the soil that came out of the hole, either as it is or with compost, or sand, or both mixed through it depending on your soil type. Firm the soil down but be careful not to compact it, the soil needs small amounts of air to stay healthy.
To stake or not to stake? That is the question.
For a small tree in a sheltered spot you probably will not need one. For a larger tree or in a more exposed position you probably will. The stake is there to hold the roots in position so they do not move in the ground and can grow out from the hole. For this reason, it only needs to be about a third of the height of the stem. The stem gets stronger by swaying around in the breeze so it is important not to stake the tree too high.
The last stages are to apply mulch around the base of the tree and water it. Mulch as far out as possible and to a depth of 50mm. Well-rotted wood mulch is best, ideally to the drip-line (edge of the canopy) of the tree. Mulch keeps weeds down, keeps moisture in, acts as a slow release fertilizer, and negates the need for mowing right up to the stem which can cause damage. At the start, water the tree every 2-3 days with about 20 liters of water. This may need to be adjusted for very dry or very wet conditions or for larger trees.
Finally, grab a chair and your favourite drink and sit back and enjoy your handy work. If all has gone to plan you should get many years of enjoyment with very little further effort. More information about planting trees can be found here https://www.arborday.org/trees/planting/