In message , Peter Brown
writes
I've tried unsuccessfully for years to grow Viburnum as a hedge in my front
garden and have just dug up the soil to discover that the soil is heavy clay
after about 6-7 inches. The top 6 inches has clumps of clay in it. Can
anybody suggest a good hedge for a site that gets good amounts of sunshine.
Somebody suggested a PYRACANTHA (especially Mohave). Any comments??

You have chosen unwisely.
And how deep did you plant these poor unfortunate hedging shrubs?

Among the things suitable for hedges that grow well in our heavy clay
soil are pyracantha, privet, holly, beech, cotoneaster, yew and
hornbeam. I reckon they look best planted in segments about 3-4 metres
long all the same species.

Depending on how thorny or toxic you like your plants some may be
inappropriate choices for your garden.

Regards,
--
Martin Brown