Delphiniums in the Midwest

Margaret --   I have seen Dowdeswell's delphiniums and it is easy to see why
you want some.  Me too!  The problem is that the English climate is very
little like the US climate, especially here in the Midwest where you and I
garden. 

Most of the experts around here say you can't grow delphiniums in the St.
Louis area.  Well, it can be done, because I do it.  I just love them so much
that, like you, I have to try.  That is really odd for me because my
philosophy of gardening is to grow the right plant in the right place.  I grow
mostly natives and insist on having only plants that don't need pampering.  I
see my yard as more of an ecosystem than a garden.  And we have so many
wonderful, wonderful natives to choose from.

And yet I make an exception for delphiniums because they are so lovely and I
just adore them.  They are one of the few plants I consider worth pampering.
So I give them lots of special attention.  Since the rest of my plants don't
need much, I can afford the extra time.   They need staking, dividing,
deadheading, watering, topdressing, and constant fertilizing.  Not a plant for
beginners or the lazy.  

You are right, you should amend your soil for delphiniums.  They like rich,
organic, moist and well-drained soil.  If the soil is not well-drained they
will get crown rot.  
If they are too dry they won't grow or bloom.  That is a nice balancing act -
moist and well drained.  Best done by adding lots of organic matter (I use
compost) to the bed and then keeping them watered, but not too much water or
they get powdery mildew, etc.  Delphiniums prefer slightly alkaline soil.  As
organic matter tends to be acidic, I also add some lime in the form of calcium
magnesium carbonate.  After preparing the bed and getting the plants
established, I top dress with compost and lime every spring.  

Delphiniums are heavy feeders.  If not fertilized regularly they just sit
there and pout, refusing to grow or bloom. The annual topdressing of compost
that serves the rest of my plants well is certainly not enough for my delphs.
That well-balanced diet of nutritious, homemade compost food is not enough for
them.  They are fast food junkies!    

If that were not enough, they are susceptible to lots of diseases. Although,
knock on woodys, I have not had any disease problems with mine.  And they are
often short-lived.  I just keep adding a few plants each year, and I have been
letting them go to seed after the second bloom, so I always have a new crop to
replace any that fade away.  

You can do all of that, but the biggest problem with growing delphiniums in
the midwest is that they just do not like our climate.  You can amend the
soil, but you just can't amend climate.  I always put them in the back of the
garden (which is a good idea anyway since they are tall) and try to put them
where they will get lots of morning sun and then be shaded from mid-day on in
the heat of  July and August.  
I try to shelter them with plants that emerge late and get large by late
summer.
They really like more sun than just in the morning, but they can't handle the
heat here so it is a compromise that must be made.  In the hot sun of the
midwest they slow down, sometimes even die.  (They are much more disease-prone
in full sun, too.  And I think that is true anywhere.)    

Have you tried the belladona delphiniums?  They do much better in midwest
climates, especially Delphinium x belladona 'Bellamosum'.  That, and the old-
fashioned species delphiniums are much easier to grow here.  They have a
longer bloom time, and more flowers, but the flowers are smaller.  They are
fine plants, but not so grand as those Dowdeswell beauties.  Some of the big
D. elatum cultivars are more heat-resistant, too, like the 'Blue Fountain'
strain.  I like to fill in with the belladonas and then have a few grand, huge
stars as focal points among them.  

And so, Margaret, if I can grow Delphiniums in Missouri, then you can grow
them in Indiana.  Have fun, and good luck!  --Janis, Zone 6, Missouri










In a message dated 98-11-18 12:06:04 EST, Margaret wrote:

<< Thank you.  A nice post is always welcome.  I have only bought plants of
 the plants you listed, but I'm going to have to train myself on delphiniums
 because Dowdeswell will be collecting fresh seeds from his English delphs
 in January (in NZ), and I want to grow some.  I'm going to have to
 seriously amend my soil, though, because a friend did start some of his
 plants last year and gave me a few, and those that didn't just up and die
 didn't do much at all.  It's probably also a matter of water.  We're on a
 meter and the water company keeps getting rate hikes to pay for extending
 their system.  Grrrrr.  A dry summer can give us $100 per month water
 bills.  Margaret
  >>

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