Re: Delphiniums in the Midwest

Janis,


At 12:40 PM -0500 11/19/98, LONDE@aol.com wrote:

> 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 forgot mulching. :) It's a big relief to hear that someone with
climate like mine is having success with delphinium.

Encouraged by some success with the much easier-to-grow and still
blooming :) blue butterfly delphs I have made up my mind that I will
manage the big guys if I have to haul an air conditioner outside for
them. My time doesn't even begin to allow a garden full of fussbudgets
but big delphiniums are the one plant I've decided is worth almost any
effort to grow.

> 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.

Has anyone tried amending their delphinium beds with some very fine
limestone gravel? Since soil around foundations tends to go alkaline I
was wondering if limestone gravel might serve the same purpose. It
probably wouldn't hurt drainage-wise either.

> 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.)

All but nine of the Dowdeswell delphiniums I started this spring were
lost to the Great Lawn-mowing Kid Shutting the Cold Frame Debacle of
'98 (along with 300+ other seedlings). I left six of the survivors in a
spot shaded by dark window screenig and planted the remainder in a spot
that gets no shade at all and mulched them well. The ones in full sun
started looking like they weren't going to make it at about 90°F and
croaked at 96°F. The shaded ones had a serious late summer pout but
bounced back strong when temps cooled down. One plant is now blooming
for the second time. Extended temps above the mid-80's seem to be the
point at which they stop growing.

I live in Kansas City and, while this summer seemed more humid than
normal, it wasn't particularly hot. Having temps above 95°F for the
better part of a week or two with high humidity is not all that
uncommon. I don't think that there is any way that delphinium is going
to make it in full sun with that type of climate.

I thought that annual vines grown on the south and west sides of a
delphinium bed might provide the much-needed late summer shade. When
the temperatures cool down you could take the vines out or cut them way
back. Has anyone tried something similar? It seems the key to this
strategy would be vines that are sufficiently large by the time the
worst of the summer heat hits. I also wondered if sunflowers might work
for shade.

Starting seed indoors in July also sounded like a good idea. It seemed
reasonable to think that a plant that's had a full year to grow in
conditions to its liking would be in much better shape to weather
brutal summers. I started the remainder of my Dowdsewell seed in July
and put the pots outside when the weather cooled. I have my fingers
crossed that they will winter over without too many casualties. This
worked well for the blue butterflies I experimented with last year but
last winter was extraordinarily mild and they are particularly
cold-hardy.

BTW, is Terry Dowdsewell still subscribed to the list? It's not like
him to miss out on a delphinium discussion? :) Does anyone have any
idea how cold-tolerant the Dowdsewell delphs might be? I don't think
New Zealand has very cold winters.

Dowdsewell has a page http://www.delphinium.co.nz/growingpots.htm for
growing delphs in containers. Moving container grown plants to shade in
the worst of the summer heat might be a last-ditch strategy for those
of us living in delphinium-unfriendly climates.

>
>  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

Try one of the drip irrigation kits. They are very easy to install
yourself, save amazing amounts of time and make very efficient use of
water. I consider drip to be the best payback of investment in both
time and money that I have made in my garden. Containers and baskets
would be impossible for me without the drip system.

---
Peggy Enes (peggy@unicom.net)   Zone 5/6    NE KS     AHS Heat Zone 7


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