First off: yes, I know it should be “six feet is taller than I am,” not taller than me. Sometimes you just gotta do stuff for dramatic effect and when I say that in a lecture and stretch my hands over my head, it gets a big laugh!
This whole post is really based on two sayings I developed while I was working in retail gardening. Six feet is taller than I am is one. The other is “plants can’t read.” No matter what happens, that still holds true.
So with that said, here are some tips to remember when you’re at the garden center–or where ever you buy plants–and when you get those new plants home and you’re trying (if you’re like me) to shoehorn them into your beds.
When planting, remember to leave room in between the plants to accommodate their mature size. (see what I mean–I break this rule all the time, especially with shrubs, and then I’m so sorry later. I forget the 6′ is taller than me rule!)
In the first season, if you follow those spacing requirements, the garden may look sparse. Mulching in between the plants will help unify the bed–or planting annuals in between for a year or perhaps two in the case of a shrub bed–will allow the plants to fill in to their mature size without being over-crowded.
Remember a few things about newly purchased plants. Take those size and spacing requirements liberally. Sometimes a plant straight from the garden center will behave differently the first year in the garden than it will in succeeding years. It may grow taller–or shorter, in the case of mums and asters, for example–than the tag indicates.
Also, with respect to ultimate height, remember how big 6′ can be. I’m guilty of buying shrubs in the 4-6′ range and never remembering that if they’re happy in my terrible soil, they will get almost a foot taller than I am.
I think this is what really happens to me–it’s not that I “forget” how big 6′ is. I just always presume everything is going to be unhappy in my wet, clay soil and will only grow to the shorter end of its 4-6′ range. Every once in a while, some shrub really likes my conditions–go figure–and then I’m sorry.
Nursery pot size can sometimes be deceiving with shrubs. Those shrubs that look cute and dwarf can still grow large, if that is what the cultivar is designed to do!
And don’t be deceived by words either. Words like “dwarf” still mean “dwarf for that particular species.” I can’t tell you how many folks bought ‘Paliban’ or ‘Miss Kim’ lilacs and put them in inappropriate places thinking these were teeny tiny shrubs. They’re still 4-7′ shrubs. That’s dwarf for a lilac, that might normally grow 15-30′!
With all these tips, once your garden does get the warmth of spring, they should be beautiful and well-designed.