Asters, mums and heat

aachenelf z5 MplsSeptember 12, 2011

I'm wondering if anyone else has this problem?

September around here is a weird month temperature-wise. Temps can be all over the place and yes, I hate to say this, but our first traces of snow can fall this month. More often than not however, we get a good blast of summer heat for at least part of the month. Recently it's been in the 80's to low 90's for a couple of weeks with not a drop of rain in over a month and very low humidity. My early blooming mums and asters are not happy.

I've been keeping everything well watered, but many of the buds and flowers on the mums and asters simply dry up. The flowers that open look fried within a day or so. Temps are going to fall like a rock starting tomorrow with highs later in the week only in the 50's and 60's, but what do you do about the hot days or don't you have that problem? Maybe I should only grow later blooming varieties, but that can be tricky too since October can bring really cold weather and major snow.


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hostaholic2 z 4, MN

Kevin, great post. I've had the same problem. Mammoth Mum dk Pink daisy went to the compost this spring because I got tired of the fried look. On the other hand aster October Skies and Alma Potscke blooms seem to shrug off everything. (Though Alma has a nasty propensity to flop for me). New this year is aster Vibrant Dome, we'll see how that one does. Oct. Skies is just starting to bloom.

    Bookmark   September 12, 2011 at 10:50AM
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ken_adrian Adrian MI cold Z5

way back in the day .... i used to remember mums coming in sponge-like peat media ....

the problem is.. when you plant a wad of that type of stuff.. in a vastly divergent native soil.. the interface.. or interplay between the two .. will basically kill the plant ...

e.g. if i were to un-pot a hosta in high peat media.. and place it in my mineral sand.. by july/august.. the sand will wick all the moisture out of the peat.. and it will NEVER re-wet .. and the plant will die ... so it is imperative that i bare root all plants going into the sand ...

so its not just the lack of rain.. but perhaps the divergence..

all that said . ... mums root rather easily .... and if you can get some rooted.. you might want to try them in native soil .. and see if you get any better response ...

also ... hothouse mums.. produced for one time fall flower .. are not all made equally .. there is quite a zone variation on them ... and many of them are simply not hardy in z5 .... so some of the ones at the bigboxstore are basically throw away.. one season plants ..

i wish i could recall who i ordered from back in the 90's ... like 1 to 3 dollars for rooted pieces in spring, which would turn into full plants by fall .. i had upwards of 30 varieties .... anyone??? ... lee's mums????


    Bookmark   September 12, 2011 at 11:17AM
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aachenelf z5 Mpls

hostaholic - Interesting. This is my first year with Mum Mammoth Pink Daisy. I also have another Mammoth (something or another), but they are still in bud stage and won't bloom for a while. Aster Alma usually survives the heat problem for me because it blooms later. Same with Purple Dome. Yes, I agree flopping is a big problem with Alma, but I love it so much I need to have it. If I would only remember to stake earlier in the season.


I never ever buy the big, potted mums. I always start out with what you indicated - the smallish, rooted plants in spring. I've also been buying from a MN grower where a lot of the plants they sell were developed at the U of MN, so they should work in my climate. Like you said, you can pick them up this way for about $2.50 or less per plant in the spring and have nice, decent sized blooming plants in the fall.

Here's where I get mine.

Here is a link that might be useful: Mums

    Bookmark   September 12, 2011 at 12:11PM
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ken_adrian Adrian MI cold Z5

yeah.. i was shotgunning it a bit.. perhaps other newbies will take note ...

the order form at your link is akin.. heck.. at 2.50 each.. may as well try them all ... well.. that was back in the days of no kids ...

i think it was huff's ... which went by the wayside ...


    Bookmark   September 12, 2011 at 12:47PM
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All I can say I'm green with envy. With much rain in September I'm nearly sure I will not get flowers on late Aster novae-anliae cultivars at all. The same applies to Aster oblongifolius cultivars(I have thrown them out -never bloomed)and late Chrysanthemums. Andeken an Alma Poetschke is floppy for everybody. It was the first aster I threw out. There are 2 non-floppy Aster novi-angliae cultivars here in Europe: Andeken an Paul Gerber and Rudelsburg, both with relatively small flowers.Marina Wolkonsky stands relatively well but it is not a very prolific bloomer.

    Bookmark   September 12, 2011 at 12:56PM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL(8B AL)

Ken, that explanation was beautiful. Totally agree.

Peat: Don' repeat (or replant!)

    Bookmark   September 12, 2011 at 2:38PM
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Don't fight flopping. Cut Alma Potschke back by half at the beginning of July.

    Bookmark   May 27, 2013 at 1:48PM
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aachenelf z5 Mpls

Alma - despite it's height - has never been a terrible flopper for me. It does a little, but not enough to make me crazy. Just for the heck of it, I will pinch it in July. Thanks for the reminder.


    Bookmark   May 27, 2013 at 3:09PM
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