Glad you decided deep plug plants are the way to go. (See previous post for a few good reasons why.) Now, how to calculate the number of plants you’ll need?
Plant information gleaned from various sources tell you the ultimate size of a plant, including its width. So it should be relatively easy to decide how to lay them out, right? If you want the plants to touch at their edges, plant them as far apart as they will grow wide? So, a plant that is 24″ wide at maturity gets installed 24″ away from its neighbor? Well, it’s more of an art than a science.
Plants that go into the ground smaller than their ultimate size will show space – sometimes lots of s..p..a..c..e – between them, if you plant according to standard calculations. That space has no roots filling it (yet), and gets water, light, and air … making it a prime target for competing weeds to take hold. But if you plant those small plants right next to each other, they will crowd each other out in no time flat. What’s a gardener to do?
A happy middle ground, of course. We suggest bumping up the quantities you order about 20%-30% from the regular guidelines, which will allow you to plant a bit closer than ‘normal’. The plants will still have room to flourish. They will fill in quickly, closing the ground plane gap and lessening the chance for weeds to germinate. They will not be so close that they choke each other out.
And you? You will look great to your clients. You saved them money by using plugs. You saved yourself time in followup maintenance because fewer weeds will have a toehold. The landscape? It will not have that gawky first-year look of plant-gap-plant-gap-plant.
Everybody’s happy. Except the weeds.