Our plug plants are now all potted up and are either growing away slowly in the polytunnel or sitting on heat-mats back at the house to accelerate root growth. All of our plants are grown in trays of 10 cells; each cell is 7cm square which is a about the same size as those 6-cell trays that annual plants tend to come in. The reason I chose to grow in units of ten is encourage people to plant the way bees like to forage. Bees like to maximize efficiency and look for a clump of the same flower type so they can fill up with only a short distance between flowers.
They never mix pollen or nectar from different flowers types so they may never bother to visit a single plant with only a few flowers. Honey bees, in particular, take this so seriously that they are prepared to go a longer distance from the hive if they find a good crop when they get there; this is why they will fly up to 5 miles to visit the oilseed rape when it is in full bloom.
Therefore, our plants are designed to encourage people to plant in bulk blocks although I am very aware that this is quite different to how most people design their gardens. Ten plants, planted together will make a very attractive destination for honey and bumble bees.