Why do trees need TLC in hot weather ?
A newly planted tree arrives from the carefully controlled conditions of a tree nursery into a potentially hostile setting with all the attendant stresses. Hot dry weather can quickly kill a newly planted tree during the first five years before it becomes established, especially if planted into a hot urban environment.
Birch trees dead from water stress ( not ours !)
The right tree for the right location
Picking the right tree species is key : where a tree is planted into an unsuitable location then it becomes more easily stressed by extremes of weather, especially prior to it becoming fully established in the first five years.
We always suggest to our clients that they make their choice of species based on what we know will thrive in an area rather than what looks nicest in the catalogue. Whilst you can grow most trees in most locations, an unsuitable location will most likely lead to higher maintenance needs and either potentially slower growth or complete failure. Obvious examples include many conifer or Japanese maple species planted in chalky soils.
Getting the root environment right for your tree is key to it flourishing in its’ new environment. The planting pit and surrounds should provide well prepared soil to easily expand into and after planting the surface should be mulched heavily with compost or manure.
How much, how often to water
For your trees survival regular frequent irrigation is more important than the volume, so maintenance plans should include the logistics of staff getting water out to site. When you consider the “how often” and “how much” of your irrigation regime, you need to consider the water holding capacity of the soils. These points should be covered in the design stage so that irrigation can be done. Trees though aren’t fussy, so any water (including grey water sources like washing-up water) will serve in a pinch.
As a rough indication, then 40-60 litres ( 3-4 buckets of water ) twice per month are likely to be required in areas of low rainfall and high temperatures. When you water a tree, take into account the prevailing weather conditions, soil moisture release characteristics (sandy/ chalky/ clay ) and how that tree species responds to potential water deficits (drought ) or prolonged soil saturation ( flooding ).
Watering creates significant issues where drainage is poor, as adding water will create waterlogging and airless conditions for roots. Poor pit preperation for planting is a frequent cause of this, creating a bucket effect that gathers water.
Techniques for avoiding drought stress in trees
Tree planting will normally be designed with a watering pipe or tube, embedded underground, which allows water to quickly reach the roots rather than flow down the pavement. This also avoids disturbing roots during watering and reduces risk of fungal infection.
Where the soil becomes hard baked ( as in many clay soils in East Anglia ) then mulches can help not only be reducing evaporation, but by increasing organic content of the soil. They may need a top up regularly post planting. Gaiter bags and mulch mats can reduce water stress by reducing evaporation.
Good tree stakes and ties with appropriate irrigation system.
Monitoring tree stress is especially important if there are prolonged high temperatures. As a guideline for East Anglia, check trees when there are ten consecutive days during the growing season with temperatures of 25 oC or greater. When monitoring be aware of the visual signs, something we come back to below.
Overwatering for some species can be as deleterious as underwatering as roots will waterlog and rot. The symptoms of waterlogging are easily confused with those of water stress, includiong wilting. A waterlogged plant actually is water stressed due to roots drowning and not functioning to absorb any water or nutrients for the tree.
What does this mean in practice ?
Looking after trees in the first few years whilst they become established is critical to their survival and water stress can either quickly kill them or lead to die-back causing later poor growth or fungal infection.
Pick the right tree for the right location and consider their watering needs.
Once established with a well-established root system, trees are drought-proof and will not generally need watering. Getting them to this stage is critical for successful establishment.
How can we help ?
We can help you with a full planting plan for your site, including :
- Soil testing and ground preparation
- Choice of species and sizes
- Design of planting pits
- Costings for plantings
- Alternatives to pit planting
- Planting and aftercare
If you have issues with your existing plantings, then please do call us as we may still be able to offer advice.