Planting perennials doesn’t have to be rocket science – the guidelines are here.
A rule of thumb is to install the plant at the same height it was at in the container.
If you have the plant in a bareroot state, then you’ll see a line at the growing crown/tip where the soil used to be. Even in a washed perennial root, this line is pretty much always there (although you’ll have to look closely). Put the plant into the ground at this line.
When putting a plant into the ground, dig a dollar hole for a fifty-cent plant.
The real key (besides fertility) to getting a plant growing quickly, is to have a well-aerated soil. You want a soil with enough air spaces so the tiny feeder roots can penetrate quickly and easily.
So if the pot is six-inches across – then dig a hole that is 12-inches across.
Take the plant out of the pot and put it into the hole.
The Old Cardboard/Fibre/Paper Pots
Not many perennials come in paper/fibre pots anymore but if you do happen to get one of those, I recommend (carefully) removing all the fibre pot and not burying any of it. The old advice was to slash holes in the side of it but I’ve found it really doesn’t degrade all that quickly. If you plant the pot – slashing the sides and removing the bottom and top lip as per the old suggestions – you *have* to be extra careful with water for the first summer. You’ll be surprised how fast this soil will dry out and how much water the paper pot will take away from the plant.
Soak The Plant
I’m a big fan of soaking the garden after I plant. This “muddification” soaks everything down and settles the dirt around the plant – taking any big air spaces out of the way. Besides, one of the biggest causes of perennial plant death is folks forgetting that the roots will take several months to establish themselves out of that peat or bark mixture the nurseries use and that watering is critical for success.
You do have to check the soil immediately around the plant regularly to ensure this nursery soil isn’t dry because it will dry out (all nursery soils will dry faster than surrounding soils) much faster than you think possible and until those roots are well-established, it’s just a container plant without a container. (and you have to treat it like a container).
Water Daily For The First Week
Water daily for the first week and then start backing off to every second day for the second week and then every third day from then onwards.
Example
You can see the lines on the plants as I get ready to replant these small hosta roots. They’ll go back into the ground at the same height as they were growing. In the case of these Hosta – there is also the old leaves at ground level and the new roots at the soil line we want to bury.