There is a great tendency amongst the gardening public to buy plants too early in the season.
We are conscientious sellers and do not want the discerning public to have plants damaged or totally ruined by adverse weather.
A good indicator is the hawthorn tree. The May flower.

"Ne'er cast a cloot till May be out!" In other words when the hawthorn blooms it is time to put out your bedding plants and hanging baskets.

Additionally with later production of plants we can vastly reduce our carbon footprint with minimal fuel heating.
Later gives less risk of weather damage, reduced carbon footprint and far higher quality plants.

Why would one want it any other way?!

Andrew Ross