Will the concrete in post holes restrict root development for climber?

Question

I want to grow a honeysuckle up this post. Will it be able to grow fine or will the concrete supporting the pole cause problems for the roots? I ask cause we made the mistake of digging the post holes too big. It's a foot long from all ends of the post where as it should have been only 6 inches wide.

Answer 1

Concrete tends to cause soil to become base over time (as opposed to acid). This will act like a mild form of adding a lime soil additive. Concrete is chemically the same as limestone (limestone and the cement in concrete are both calcium carbonate). In fact, burying small broken chunks of concrete acts as a poor man's way of lowering PH in your soil.

Honeysuckle prefers a PH of 6.1 to 6.5, (a slightly base PH) but will also grow outside that range. If you plant something else that likes a more acidic PH, or your soil is very alkaloid (like some desert areas) you might want to use an additive such as compost to make your soil more acid to counteract the concrete effect.

Other than changing the acidity of your soil, the only other impact will be that the roots of plants will react to concrete as a rock; that concrete will not be friendly to new root penetration as the plant grows.

If the concrete has just been poured, it will give off carbon dioxide as it sets up (goes from runny to hard) which takes from hours to multiple days, depending on the specific variety of concrete. This CO2 emission will end once the concrete has hardened but should not affect your plant unless you pour the wet concrete directly on the root-ball (don't do this).

Answer 2

the plant should be fine as long as the concrete does not over heat in the hight of summer.

it would probably aid the plant in terms of oxygen released passed the roots (concrete releases oxygen when wet from dry)