Amending clay soil

Asked August 20, 2018, 9:08 PM EDT

I purchased 16 Arborvitae from Costco last September I planted them all in a row they all received the same amount of water and fertilizer but 2 of them right out of the middle (not next to each other) died. Tom from Toms garden center in Albany said they were either over or under watered. I dug them up and sure enough even with the dry weather we have been having the whole filled partially up with water. My question is what can I do to amend the soil so when I replace them the same thing won’t happen again. There is a lot of clay in the ground. Thank You

Linn County Oregon

1 Response

Hi and thanks for contacting Ask an Expert.

The first thing to do is look at the hole, see if the ground is slanted near it to hold the water. Clay soil does hold water much better than loam or sand so amending it with loose compost would help with the drainage. Dig out the area and fill it with compost.
However, you need to assess the area and where the water could go. Digging a French drain may help. This is a trench that leads excess water away from the plants and is filled with gravel. Instructions:

  1. Dig a trench along the outside of your arborvitae
  2. Lay the pipe (usually about 6 inches in diameter with holes on the top to receive the water) on the soil.
  3. Cover the pipe with at least 12 inches of gravel.
  4. Lay filter fabric over the gravel to prevent any soil from clogging the pipe.
  5. Back-fill the foundation with top soil back to its original grade height.
There are a lot of instructions online for French drains.
Before you dig a trench there are some things to consider:
Was the hole near both the plants - you stated they were not together.
Is there an overall drainage problem with all of the plants?
Did the winter rains drain off the area or stand in the area?
These questions may help you decide if you need a French drain.

Also Arborvitae have shallow roots so digging in the area could damage their roots.
If you have any further questions, please re-contact us.