Problems with Crocus michelsonii

[John Aipassa]

Hello all,

After being absent for a couple of years, this is my first posting on the new forum.

I have a question regarding Crocus michelsonii. I have several bulbs in pots outside which appeared in December 2007. All my other Crocus species in the garden are flowering, but my michelsonii stayed closed. Close examination resulted in having buds completely rotted. A gentle pull of the leaves ended up in pulling the complete plant out of the pot, leaving the bulb in the pot. Although the leaves were still green, the connection with the bulb was mushy and rotted. Why has this happened? Is it because we hardly had a winter this year in The Netherlands, with hardly any subzero temperatures or snow? Or is it because I kept the bulbs in pots outside and should I have kept them in a greenhouse?

Anyone? Thank you.

John Aipassa
Aalten, The Netherlands, where we have sunny weather and temperatures of 11'C right now.

[art600]

John

I too would like an answer.  Growing michelsonii for the first time, one pot had a wondeful bloom on ne corm, exactly the same problem as you described on another corm and the third corm is yet to show.

What did you do with the corm?

[Thomas Huber]

Hi John and welcome back!

Crocus michelsonii is one of the most difficult of the genus. I grow mine outside
protected by a deciduous tree. This worked fine for me in the last two years. But
I have never dared to let them outside during our wet summer - I've always lifted
in June and planted back in the ground in September.

If you have them in a pot outside the water balance is not as good as in the ground.
Even if the surface looks bonedry, there is still plenty of moisture down in the pot
because the water can not distribute as much as in the open. The falling rain  
accumulates in the pot if the mix isn't extremely well drained and can cause such
signs as you described. Which kind of soil do you use in your pot?

I would recommend to have a look at the corm - if it's still alive replant it in well
drained soil and put them in a dryer place!

[John Aipassa]

I have not looked at the corms yet, but I will today and give you my findings. I appreciate your comments Thomas and I think you have the answer. Having left the corms in the pots outside it must have been too wet for them. I hope the corms are still OK. If they are, they go straight into the ground under deciduous trees like yours.

Thanks

John Aipassa
Aalten, The Netherlands

[John Aipassa]

I Checked the corms and guess what?
I have successfully killed all the corms . All were mushy. In my ignorance I didn' t want to plant these priceless bulbs in the garden, being scared that rodents might get a bite of them, stupid . My potting medium was 1 part potting soil, 2 parts course sand and 2 parts perlite.

Thomas, how did you prepair the soil under your trees for your michelsonii?

Thanks

[Thomas Huber]

John, I've mixed my soil in the open with lots of sand and fine grit.

Your soilmix sounds good.
Perhaps your corms would have survived if they were not growing in the open.
Careful watering with the watercan from time to time is much better than letting
the rain on it! Most of my friends grow michelsonii in pots, the only one I know
who grows it in the open is Leonid Bondarenko. But he has much "better" winters
than I have.

[art600]

Thoma

As this was my first time with michelsonii, I planted in pots that stood on a sand plunge of at least one foot.
I have been following Ian Young's directions on watering and have had excellent flowering on more than 50 pots of crocus.  Only in this one pot - the 3 cheapest corms from Leonid Bondarenko - did I have a problem.  two other, more expensive selections were fine.

Any thoughts, or is it just a difficult crocus

[John Aipassa]

Thanks Thomas,

My bulbs are from Leonid too. I will have to order some new ones now and wait until next winter to see them flower myself.

Cheers.

[Thomas Huber]

Sorry Arthur I have no further helpful comment to your problem 
Of course it is a difficult species - perhaps you just didn't have luck, so try it again!

[Gerry Webster]

John, this is not directly related to your problems with C. michelsonii (which I don't grow). However, I have grown crocus  for years in pots plunged in uncovered sandbeds.   For the first time ever this year  I have had crocus rot off in the manner you describe - C. cartwrightianus, C hadriaticus & C. niveus. Only one corm per pot was affected so it seems unlikely that drainage is the problem. I use a compost of 3 parts John Innes no.3 to 2 parts 6mm limestone chips.

[Anthony Darby]

I plant mine in the same mix that Ian Young recommends (50% grit), but they have a dry summer in the greenhouse, where they are all year, very like my mediterranean orchids and narcissi. I would never chance them outside. Mind you, unless the plants is a bone fide bog plant it is hopeless trying to grow it outside in Dunblane.

[art600]

Thomas

Having emptied my pot of michelsonii, I now know why I had failures.

Attached photo - apologies for poor qulity but I killed the grub before I viewed on full screen - shows one of 5 grubs in the pot.  One grub was actually emerging from the corm that had shown signs of distress.  Unfortunately I did not have camera to hand to capture the moment.  Corm still feels solid.

I am now worried as my crocus are in pots close together.  Is there some treatment I could give to eradicate the possibility of grubs in other pots?
How to kill the grub in the damaged corm - could be same treatment I guess.
What is it - did it come in the corm?  If yes, can I treat all corms before planting.

Would appreciate your thoughts from your experience

[David Shaw]

Not a pleasant find, Arthur. What sort of grub is it, it looks like a wireworm?
Where do you get your compost from? Do you mix your own using loam from rotted down lawn turf? Wireworms like to live in the grass roots beneath lawns and could have originated from the loam. I use this material for my own potting composts and have learned to inspect it closely for wireworm as I sieve it out.
As for treatement I will leave that question for someone else.

[art600]

David

Do not think it is a wireworm.  Wish I had taken a better photo, but wanted to kill it quickly.  Would say it was about 0.8 inches long.

I make compost from commercial John Innes mixed with grit and some all purpose compost.  Depending on what I am growing I add leafmould - lucky to inherit a large quantity when I bought the bungalow.

[Anthony Darby]

I would agree with David: wireworm, which is the larva of a species of Click Beetle (Elateridae). They look superficially like a tough, shiny Mealworm (Tenebrio spp.).