How to water your trees
We all love trees don't we? They are beautiful to look at, the provide shade, and they give the planet the oxygen we all need for life itself. We take care of the trees we have and value them highly. What should we do to ensure our trees live long and healthy. The most important thing is CORRECT WATERING.
Newly planted trees: Immediately after planting, all tree roots are in the original root ball area. Until new roots grow into the soil of the planting site, water the original root ball area and just beyond this area. The root ball area may dry out faster than the surrounding soil, so check the moisture in this area frequently for the first month or two after planting. A newly planted tree may take 1-2 years to become established. Larger container stock trees may take longer to become established than smaller stock. Never water a tree at the trunk, but within a diameter equal to the height of the tree or bush for the first two years.
Established trees: An established tree that suffers root loss or damage (for instance, due to trenching within the root zone) may need additional irrigation until new roots grow to replace those that are destroyed. The root system of an established tree that has not suffered root damage extends far beyond the boundary of its leaf canopy. The roots at the trunk anchor the tree but it is the roots at the drip line and beyond that absorb the water the tree needs.
The drip line is found directly below the limits of the tree's canopy. When the tree's canopy gets wet, excess moisture is shed to the ground where the feeder rootlets are located. Rain also falls outside the drip line and a mature tree's root system can extend up to twice or three times the extent of the canopy. When you irrigate or fertilize the tree, it is essential that you do it within reach of the feeder rootlets at and/or beyond the drip line, or the water will be leeched away and mostly lost. The drip line is a plant's dinner table; put the nutrients on the table.
DO NOT water at or near the trunk of the tree. The tree cannot take up water in this location and you will encourage fungal diseases to enter the bark which will eventually destroy the tree. Water in the outer half of the area under the canopy and beyond the edge of the canopy.
Killing me Softly: Most old or established trees need very little watering. The daily brief sprinkling that is applied to lawns is detrimental to trees growing in the same area.
How to irrigate:
Water used by trees is stored in the soil. Soil type, depth, and condition influence how much water can be stored in the soil, and consequently how often you may need to water your tree. Soils that have more clay hold more water and can be irrigated less frequently. Sandy soils hold relatively little water and need more frequent irrigation.
Water deeply rather than frequently. Because most tree roots are found in the upper 18 - 24 inches of the soil, this is the zone that should be wetted up in each irrigation cycle. Each deep irrigation will meet a tree's water needs for between 10 days to 4 weeks during the hottest part of the summer, depending on the tree species and soil type.
Stop watering when runoff starts. Soils high in clay accept water slowly, often as little as 1/4 inch per hour. Water infiltration is especially slow in compacted soils. If water starts to pool or run off, stop irrigating, let the water soak in, and start watering again. Repeat on/off cycles until you apply enough water to wet the soil to 18-24 inches. This may take a number of cycles over several consecutive days.
Don't saturate the soil for long periods. Water displaces air in the soil, so long periods of soil saturation can suffocate growing roots. Take a long enough break between irrigation cycles to allow the free water to be absorbed. If in doubt, probe or dig to make sure that the soil isn't soggy below the surface.
How much water does my tree need?
Tree irrigation needs change over time. The amount of irrigation your tree will need can be affected by:
Time of the year: The need for irrigation is greatest in mid to late summer, when temperatures are the highest and most of the moisture stored in the soil over the winter has been depleted.
Weather conditions: In drought years, soil moisture is used up earlier in the season, so the period of peak water need is longer. Some trees that do not normally need irrigation may benefit from irrigation in drought years. In very wet years, irrigation may not be needed until early summer or later.
Species: Some tree species require no additional irrigation once established, whereas others will do poorly without consistent irrigation throughout the summer. Find out how much water your tree needs.