Watering Trees in the Fall

Rain; too much and we worry about flooding, too little and we worry about drought. But do we need to worry about how much rain falls in the Autumn? Trees are losing leaves and going dormant, aren’t they? Plus, snow is on the way, whether we like it or not. So should we worry about watering area trees in the fall?

The answer is YES, but watering trees in the fall is all in the timing.

Trees require a good soaking before the ground freezes for winter

Watering Trees in the Fall

The simple answer of whether to water trees in the fall is yes, but timing is everything. In the fall, trees do indeed go dormant. Growth slows and leaves drop. But if you continue to water your tree while it is going dormant, it struggles to go into that dormancy and keeps producing new growth. When temperatures drop and frost hits, any new growth that has formed late in the season is in danger of being damaged.

Confused? Don’t be.

In early Autumn stop watering your trees so that they can go into dormancy. For deciduous trees (trees with leaves), wait until all the leaves drop, then turn on the water again. Once the leaves have dropped, your tree will no longer produce new growth, so you can go ahead and water again. For established trees, water along the tree’s dripline (outer edge of where tree’s canopy extends). Newly planted trees should be watered at the root ball. You want the soil to be moist (NOT soggy). Keep watering until the ground is frozen.

While coniferous trees don’t lose their needles, it is even more important to water them before winter freeze sets in. They don’t go into full dormancy, so lose moisture through their needles any time temperatures rise above 0°C.

Doesn’t snowmelt offer enough moisture?

The problem with snowmelt is that snow sits atop frozen ground. Even if you get a mild day or two mid-winter, the tree’s roots cannot access the water. Watering deeply before the ground freezes gives roots access to it on milder days and in early spring before the ground thaws. Ensuring the soil is moist at least 1-2 feet down encourages proper root growth.

So while the leaves slowly start to change colour, sit back and relax to enjoy the show. But don’t put the hose away until after you have soaked in your trees for their long winter’s nap.