Perennials with Personality

 by Lynn M. Koch 

This spring I had the good fortune to hear Karen Rexrode give a presentation entitled “Perennials with Personality’.  If you are not familiar with Karen, she is the former owner and founder of Windy Hill Plant Farm, perennial specialist, and photographer, as well as a great speaker.  She is now an estate gardener at Oak Hill.

For this talk, she borrowed off ideas presented in “Planting Design – Gardens in Space and Time’ by Piet Oudolf and Noel Kingsbury (pub. 2005).   The theme was that there are basically 4 types of growth strategies for plants designed for their survival, although they do not always stay within one group.  While we like to ‘judge’ plants for their beauty, plant growth is actually about their survival.

Karen discussed 4 categories plants have that she uses to place her plants in the landscape.  She admitted that the areas are very gray, and there is often crossover, but the important thing is habitat.  This seems basic, but it’s a good refresher when we try to think about seasons, layers and massings (i.e., once it’s over, what’s next?)

Stress Tolerators:

• Grow slow
  
• Have tough evergreen leaves
  
• Have small leaves and are physically tough
  
• Flower early rather than late
  

Examples include – Helleborus, Rhodea, Epimedium, Iris, Grasses, Yucca rostrata, Lavender, Delosperma.  These plants need good drainage, poor soil, full sun (even Helleborus tolerate full sun under deciduous trees). 

Personality:  Independent, determined
These plants bloom early so pollination is assured, and are often deer resistant.

Stress Avoiders:

• Grow seasonally
  
• Often flower early, producing a lot of foliage afterwards
  
• Have a bulbous root system
  
• Have long periods of dormancy
  

Examples include - Mertensia and the many geophytes (bulbs)

Personality: Practical, idealistic
One of the better combinations to plant are these with plant ‘Competitors’, such as Primula sieboldii under hosta and ferns.  

Ruderal or Pioneers:

• Rapid growing
  
• Have showy flowers and flower over a long period
  
• Produce large quantities of seed
  
• Die young
  
• Easy to grow from seed (no mulch)
  

Examples include - Larkspur and biennials, Columbine, Dianthus barbatus (if you do not deadhead it).

Personality: Risk takers, live for the moment
True annuals belong in this category.  Deer and rabbits tend to munch them, and they often seed in various locations due to wind.  They don’t need much to germinate (no mulch!) and ‘wait for the light’.  i.e., even after many years, seeds hidden in areas come to life after exposure.  Over the long term, these plants might get messy and need more time to manage them.

Competitors:

• Are tall
  
• Grow fast to occupy space
  
• Are able to rapidly extend shoots sideways to occupy vacant space
• Have large soft leaves
• Flower relatively late (since they are busy taking up ground first)
  

Examples include – Rudbeckias, Hemerocallis, Aster, most Salvias, hardy Geraniums, grasses, Helianthus, ferns

Personality: Assertive, outspoken
These plants are easy in that they help keep out weeds, extend sideways via rhizominus roots and can be easily ‘whacked’ back.  These can be cut back in June and July to keep them from falling over.  Solomon seal with Japanese painted fern are both competitors, but great in massing.  Keep these plants in control by pulling out ‘extras’ and giving them to friends (or your compost pile).  Their lines need to be managed.

So next time you are designing with perennials, think about their ‘personality traits’ before you put combinations together.  The end result will provide seasonal beauty and happy plants!