Nursery's (me included) usually offer a variety of sizes of perennial plants.- price range to fit different budgets
- not everyone can dig a hole for a 2 gallon plant
- how close is the plant to the house - more instant gratification
- how large will the neighboring plants be (if any) try to maintain size balance, and a tiny plant next to mature one could become too shaded & would lose in the fight for water & nutrients
- what time of year is it? In the spring you can get by with smaller plants as they have all season to establish themselves. Late August and beyond, I would recommended a gallon size or large as time is running out to get established before winter.
- how much care will you give the new plant? The less reliable you are for watering at least once a week, the bigger more established plants you should get. A smaller plant will have a lesser chance of survival when neglect is involved.
It helps to keep moisture more even, keeps soil temps more even and warmer longer as it acts like an insulater. Sometimes plants just need an extra week or 2 to get established.






