You should not need to worry about frost heave with your no-dig fence for two reasons:
- Concrete footings have enough surface area for frost to get underneath and heave up the footings. A pipe anchor has a small diameter making it much more difficult for frost to get enough leverage to heave.
- In the rare event that a pipe anchor does heave due to frost, it’s relatively easy to fix. You just need to unzip a few screws to dismantle the offending post, fix the heaved pipe anchor, and reinstall your post.
The no-dig fence concept was actually developed in Western Canada due to extreme frost conditions. No matter how deep the fencers dug concrete footings they would still heave out of the ground, and when cement footings heave they are virtually impossible to fix. As such, most vinyl fencing in Western Canada today is installed with no-dig pipe anchors to mitigate the damage frost can cause to a fence. For more information, see this blog entry.