Watering white cedar trees

(Question)

My question concerns how much to water newly-planted white cedar trees.

The bottom of my back yard has about a 6-7 foot high wooden retaining wall, at the bottom of which is the driveway of a townhouse complex that borders the back of my property. There is a wooden fence on top of my retaining wall.

In June I had some landscaping done and for privacy, I had a row of about 20 white cedar trees, 6-7 feet high, planted at the bottom of the back yard along the fence. The landscaper told me they need “plenty of water” and we laid 2 rows of weeper hose, 1 row on each side of their trunks. So there’s one row of weeper hose between the cedars and the fence, and above the retaining wall, and a second row about 10 inches farther in from the fence and the retaining wall. There’s also about a 2″-3″ layer of mulch.

My difficulty is what exactly “plenty of water” means in practice for these newly-planted white cedar trees. I initially left the weeper hose running all night, and it appears that the water was seeping out through the wooden 6×6’s that make up the retaining wall. This was pretty alarming!! So I did some Internet research to try to get more specific guidance as to how much water white cedars require, but apart from “plenty of water”, “water heavily” and “lots of water” I can’t find anything that tells me what that means in practical terms of how often to water them and for how long.

I plan to remove the row of weeper hose that’s between the trunks and the fence, to cut down on the amount of water that seeps out close to the retaining wall, and leave just 1 row of weeper hose. After I do that, in my situation, how frequently and how long should I water them? Would running the water (with 1 row of weeper hose) for 1 hour every 2 days constitute “plenty of water”?? Half an hour every day?? An hour twice a week??

I’m trying to strike a balance between giving them enough water to do well, without giving them so much that their roots can’t absorb it and I end up damaging my retaining wall.

I would be very grateful for some guidance from a Master Gardener!! Thank you very much in advance, BW

(Answer)

You are correct that it is difficult to find exact watering instructions for white cedar saplings. However, the best advice seems to be to water your white cedar tree as often as is necessary to keep the soil moist which would be  at least once a week until the trees are established. Let your soaker hose run for up to 20 minutes to give the water time to sink deep into the soil, unless we get enough rainfall to look after this. After the roots of your white cedar tree establish themselves, water every two weeks, or as necessary to maintain soil moisture.