Theo Sanders, Germany

Rotted leaves of species

February 6, 2015

Categories: Diseases and Pests, Growing Daffodils, Pots, Soil

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Rotted bulbocodium leafs

For species and other daffodils I used as potting compost for the first time a mixture of about 50% perlite, 20% peat, and 30% heavier soil from my garden. The surface of the potting medium was protected by basalt granulate also for the first time to avoid the growing of moss. During autumn and winter we had too little sun and the plastic pots stood mostly at five degrees C in the greenhouse. Some plants rotted as is to be seen for a bulbocodium in the picture. With another compost and no protection by basalt granulate I never saw such a rotting before. Does anyone have an explanation for this behaviour? Does it come from the basalt granulate or an ingredient of the potting mix?


4 responses to “Rotted leaves of species”

  1. Mary Lou Gripshover, Ohio Mary Lou Gripshover, Ohio says:

    Hi Theo,

    I use Pro-Mix, which is a peat-based growing medium, and I mix in some granite grit (sold here for poultry farmers) for added drainage, then top the pot with granite grit to keep the soil from splashing out of the pot during a heavy rain, or overwatering.  Your mix sounds very similar.  I occasionally have a bulb with rotting leaves, but I’ve never attributed it to the potting mix.  I always suspected there was a problem with the bulb to begin with.  I’d try to get the rotting bulb out of the pot, then water the pot with a fungicide to kill any remaining rot in the soil.

    I look forward to seeing comments from others who grow regularly in pots.

    Mary Lou

  2. Mary Lou, Theo and All,

    I read your comments with interest during the week but was unable to check my pots due to it being dark on going to work and on my return!

    So this morning bright and bushy tailed I checked all my 160 pots for any signs of brown dead or dying  foliage!

    At pot No.32 I found one brown leaf in a very small pot of  N.Kidling.

    It was the only pot to show premature die back so think this is a sick bulb thing as Mary Lou posted.

    All other pots showed no signs my compost is made up of 50% John Innes No.3 with added sharp sand 35% and 15% Grit or Small Stone. Topped off with Granite chippings.

    Other factors that may hold the key are over or under watering , strength of feed and/or the weather (frost or freezing).

    Regards to All,




  3. David Adams, New Zealand says:

    Hi Theo,

    Here is my tuppence worth. The statements I make should be considered as hypotheses rather than proven facts.

    1. Given the conditions you have provided I suspect your losses have mainly been in the bulbocodium, tazetta, triandrus and some of the pseudonarcissus groups. The others may tolerate the conditions.

    2. Plastic pots tend not to ‘breathe’ as do ceramic pots.

    3. Bulbs prefer conditions similar to those found in the wild some of which have little or no soil.

    4. I find that some cultivars and species actually flower and thrive better when planted in open ground rather than pots eg ‘Little Gem’ never does well in pots for me.

    I used to make a mix similar to yours and lost many species and cultivars. Forty years ago I visited Rod Barwick for the first time. He told us he used a soil less potting mix. I thought he was crazy. Not any more and it took thirty years to work it out. Slow learner here.

    I and most of my AGS friends in New Zealand use a bark based mix which most buy as a propriety bulb potting mix from the garden center. It consists of bark, pumice, coconut fibre, added calcium, trichoderma and some slow release fertilizer. My bulbs have never been healthier.

    Thus, I am suggesting, your potting mix is the problem as it has retained too much moisture. We know that heat plus moisture equals fungus. Some species must be dry and baked in summer in order to survive. As a contrast I keep cyclamineus and its cultivars in the shade all summer

    For what these ideas are worth.

    Dave Adams

  4. Mary Lou, Ian, and David,

    Thank you for the comments. I shall change my potting mix for some sensitive species to reduce the content of water.