Re: Delph Replys replys

In a message dated 98-11-22 12:06:33 EST, you write:

<< From: Peggy Enes <peggy@unicom.net>
 Subject: Re: Delph replys
  I've mulched the dickens out of the blue butterflies (4-6" in summer)
 but I think these are a great deal less fussy than the giant delphs.
 The Dowdsewells that I tested this summer in full sun had 6" of pine
 bark mulch on them but they definitely fried from the top down. The
 roots on the one plant I checked at the time were OK but have since
 disappeared.<<

Peggy, Yes, the blue butterflies are less fussy than the giant delphs.  The
giant delphiniums are going to fry in full sun, as yours did, in a hotter
midwest summer even if they are mulched.  My experience is that you are only
going to be successful
with them in the midwest if the summer is a mild one, or if they are in
partial shade.
Mulch alone will not protect them.  They can not take extended periods of hot
midwestern sun.  The safe way around that is growing them in part shade here.
They do best in full sun where the summers are not so extreme, but If you put
them in full sun here, you are gambling that it will be a mild summer. 

>>If the larger delphinium are prone to root rot it might be worth trying
 to mulch with something that is very slow to break down like cypress or
 cedar. That should prevent an excessive or quick build-up of rotted
 mulch and still keep the delphs tootsies moist and cool.<<

Sorry, Peggy.  I did not mean to type root rot.  They are susceptible to crown
rot.
Sorry to confuse you.  Either way, the issue is not the build up of rotted
organic matter or how fast the mulch breaks down.  Any type of mulch around
the crown of a delphinium can creates two problems -- 1) Mulch holds moisture
in the soil.  If too much surface moisture is held near the crown it will
promote crown rot.  Delphiniums can't take wet feet in a climate like ours.
2) Mulch is a good hiding place for slugs to which delphs are also
susceptible.  

 >> It also occurred to me to wonder if fertilizer might play a role in
delphinium being prone to root rot. I've read that there are antifungal  and
antibacterial microorganisms in a soil with decent amounts of  organic matter
and that they don't appreciate excess fertilizer one  little bit. This would
seem to pose a potential conflict since
 delphinium like a lot of food.<<

Again, sorry for my mistake, it is not root rot, but rather crown rot.  But
your point about fertilizer is a good one.  For this, and many other reasons,
it is never a good idea to overfertilize any plant. However, the problems with
fertilizer arise when there is more fertilizer than a plant can take up.  It
the plant uses it, it is not left in the soil to create problems.  So it is
not a conflict in a heavily feeding plant such as delphinium.  But one should
not really pour on the fertilizer for any plant.  For delphiniums and other
heavy feeders, frequent, moderate amounts of fertilizer are best.  The trick
is not feeding faster than the plant can use it.  This is not as difficult as
it sounds because plants, like pets and children, usually tell you when they
are hungry.

>>I was aware of the unpleasant tendency to crown rot so I've been very
careful about keeping the mulch well away from the base of the plants--an
interesting job with 6" of mulch on the butterflies spaced 1' apart. :)<<

That is why you have not had problems due to mulching.  My entire perennial
bed is mulched in the summer.  I just keep the mulch away from the base of my
delphiniums and other slug & crown rot susceptible plants.  I am especially
careful not to mulch around delphiniums in the winter, because mulch during
the dormant period is especially conducive to crown rot disease.  You are
right, that is an interesting job!  --Janis




 

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