Research

Trees in a Changing Climate

Key implications
Coping with the effects: advice for gardeners
Tips for tree planting and establishment
Frequently asked questions
Conference

Tips for successful tree planting and establishment

• Ensure all planting is done by April and start with a healthy, well-grown plant. Choose a specimen with a healthy root system rather than plants that are pot-bound or whose roots are curled tightly around the rootball.
• Don’t submerge the stem collar when planting as the bark is liable to rot, resulting in the gradual death of the tree. However, don’t plant too shallow as the roots may become desiccated giving reduced vigour and increased susceptibility to pests and diseases.
• Bare-rooted trees should be planted so that the ‘flare’ of the roots is just below the soil surface.
• Avoid forming an inward sloping saucer as the accumulation of excess water and detritus may result eventually in stem or collar rot.
• Ensure the planting hole is wide enough to accommodate the roots when teased out.
• When returning earth around the roots, break down the sides of the hole with a fork to encourage root spread.
• Don’t over-firm the soil around the roots as this compacts it, excluding air and preventing the roots from functioning effectively.
• Sift the soil between the roots when planting and firm gently to remove air pockets present around the roots.
• Don’t let roots dry out, or expose them to frost or cold, before planting.
• Water the plant sufficiently as drought stress can occur easily even in cool, wet summers.

Tips for newly planted trees

• Control grasses and weeds in the first five years after planting as they compete with young trees for moisture, nutrients and light.
• If planting in a lawn, leave a circle of at least diameter 90cm (3ft) free from turf as this can seriously affect establishment and later growth.
• Mulch to control weeds, conserve moisture and reduce temperature extremes. Suitable mulches include woven polypropylene or proprietary tree mulch mats. Organic mulches include bark mulch, leafmould or well-rotted manure. Draw the mulch back from the base of the stem to prevent rotting.
• Water thoroughly in dry spells to ensure that the water reaches the full depth of the root system. Watering little and often may do more harm than good by encouraging roots to remain near the surface and discouraging trees from sending out roots into the surrounding soil in search of water.
• Don’t apply fertiliser in the first growing season. On infertile soils, feeding the year after planting may be beneficial.
• Carry out corrective pruning while the tree is still young.
• Inspect tree ties in spring and autumn and adjust ties to prevent constriction of the stem.
• Remove stakes after two growing seasons.

Tips for planting trees in wet soils

There are many trees that will grow successfully in soils that are permanently moist, but few will survive long spells of flooding or waterlogged conditions.

• Improve soil by incorporating bulky organic matter or inorganic material such as coarse grit or pea shingle. Do this over as large an area as possible - at least one square metre/yard.
• If severe waterlogging or flooding is a problem, consider installing artificial drainage. Improve drainage at the base of the planting hole by forking through any compacted soil.
• Fork through the sides of the planting hole or break down the sides into the planting hole when backfilling. This avoids creating a planting 'bucket' or sump which fills with water.
• On heavy soils prone to winter wet, protect the finer surface feeding roots by planting trees on a slightly raised mound (20cm/8in should do) to improve drainage around the root system.

Trees suited to wet soils

Alnus (alders)
Liquidambar styraciflua (sweet gum)
Metasequoia glyptostroboides (dawn redwood)
Populus (poplars)
Salix (willows)
Taxodium distichum (swamp cypress)

Trees for small gardens

Acer palmatum 'Sango-kaku' AGM (6m/20ft)
Amelanchier lamarckii AGM (10m/34ft)
Cercis siliquastrum AGM (10m/34ft)
Cornus cousa var. chinensis AGM (7.5m/25ft)
Crataegus laevigata 'Paul's Scarlet' AGM (8m/27ft)
Malus 'Evereste' AGM (7m/24ft)
Malus tschonoskii AGM (12m/40ft)
Prunus 'Pandora' AGM (10m/34ft)
Sorbus hupehensis AGM (8m/27ft)