The trials and tribulations of watering are probably the biggest topic to talk about in the establishment of new trees. How much water does a tree require? And how often does it need watering?
Many of the specifications I have read over the years say a newly planted tree requires 60–100 litres of water a visit. And it is suggested this should be delivered twice a week, depending on the weather conditions, which we cannot always predict.
But as we all know this is a very time-consuming job and very labour intensive. To water a tree or any plant properly, it needs to be done slowly at a rate that will allow the water to penetrate the ground within a metre diameter of the tree, with no run off. The best time is early morning or early evening when the tree/plant is not in full sun. This again increases the labour cost because you may have to pay an enhanced rate for staff to carry out this work. So, what are the options?
Various watering tubes can be added in the planting process, again to aid with the establishment of new trees. The question with these is do they help with watering or do they cause problems later on when the tree becomes established? Most are plastic and none to my knowledge are biodegradable.
Water-retaining gels can be added to the planting pit when planting new trees, and compost, green-waste products or manure all to help retain soil moisture.
Mulching and mulch mats
Mulching a 1.5m diameter circle around the base of a tree will help retain ground moisture, as will the use of mulch mats, and they keep down weeds which would be competition for the tree for ground moisture.
The reservoir system is probably the most cost-effective way of watering your newly planted and young tree stock. The initial capital outlay is quite high because of the purchase of the reservoir unit and the installation, but there are savings to be made during the watering season in terms of labour and resources. You can rapidly fill the reservoir, usually with around 90 litres, and then the water slowly percolates down, giving the tree a constant amount until the reservoir is empty. Fertiliser and feeds can also be added to help tree root establishment and benefit the growth of the new tree.
This is a slow and timeconsuming process and the most expensive way of watering trees. The cost of setting up all the equipment and the vehicle to either carry or tow a bowser is a large capital outlay, as is the labour to carry out the works.
With the planting of new street trees, it could be beneficial to encourage the local community to get involved with the watering through wildlife trusts in the area or voluntary groups involved in conservation. The contractor could even supply a watering can and give some guidance about how much water the tree needs.
Nigel Glogan is a contracts manager. He started working in the industry after leaving school and studied arboriculture, landscape construction and turfculture at college.
This article was taken form Issue 189 Summer 2020 of the ARB Magazine, which is available to view free to members by simply logging in to the website and viewing your profile area.