1. Water regularly
On average, young trees should be watered twice per week using approximately six gallons of water each time. That is the equivalent of three full watering cans twice per week or using a hose with no nozzle on a very slow trickle for approximately 15 minutes twice per week. If you are ever unsure as to how much water your tree is receiving, stick your finger deep into the soil under the mulch before watering – if it is cool and moist, your tree should be good for another day, but if it is hot and dry, your tree is in need of a drink! Monitoring the frequency and amount of water you give your tree is important because too much or too little water can impact overall health.
2. Protect the trunk
The base of a tree is fragile and can be easily damaged. To prevent this, place natural wood-chip mulch about eight centimetres deep in a doughnut-shape around the trunk to allow for air circulation. Avoid piling mulch up around the trunk as this can lead to decay. If required, apply a breathable, retractable tree guard around the trunk to avoid animal and mechanical damage.
3. Avoid chemical pesticides and fertilizers
Improve your soil and give your tree some nutrients by adding a healthy layer (approximately five to eight centimetres) of organic matter, such as compost or manure, underneath the mulch at the base of your tree each spring and fall. Avoid synthetic fertilizers as these can burn roots.
4. Avoid tying, nailing or attaching anything to trees
Even materials loosely strung around a tree will eventually become tight, causing the tree to grow over the object. Once this has occurred, the tree’s vascular (circulation) system is cut off, blocking nutrients and water from travelling up the tree from the roots. Be sure to remove any staking materials after one year and never attach anything on or around your tree.
5. Avoid digging or excavating near trees and avoid piling 
Damage to roots may take a few years to become evident and will often be fatal for trees. Remember that 90% of a tree’s roots are located in the top 50 centimetres of soil and can extend up to three times the width of the tree canopy. Digging or excavating always causes root damage, so avoid this at all costs. And piling soil or other materials within a tree’s root zone will smoother and kill roots, causing serious damage.
6. Do not prune without knowing proper techniques
Improper pruning cuts can result in serious irreversible damage to your tree as well as serious personal injury. Never try to keep a large growing tree small by pruning or topping it and do not use tree wound paint or dressings as this interferes with the tree’s natural healing process. Before making any cuts, consult the International Society of Arboriculture (ISA) or contact an ISA certified arborist to complete the work for you. We have a handy guide to help select a qualified tree care professional.
Adriana Rezai-Stevens is an ISA Certified and the Planting and Stewardship Coordinator at LEAF.
The Backyard Tree Planting Program is supported by the City of Toronto, the Regional Municipality of York, Durham Region, the City of Markham, the Town of Newmarket, the Town of Ajax, the City of Oshawa, the City of Pickering, the Township of Scugog, the Town of Whitby and Ontario Power Generation.