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Penstemon seedlings

I am in the process of growing alot of seedlings under lights. I have succesfully grown dianthus deltoids, campanula carpactica, lobelia trailing type, snow in summer, aubrita and pansies etc under the lights but for some reason my pestemon seed leaves go brown and shrivel and the seedling dies. I thought perhaps it was my lights which I found strange as penstemon are from a much hotter brighter climate than most of the other seeds so i took the lights off and placed on windowsill, However ones that have sprouted since the others died are taking ages to develope a true set of leaves and some are starting to die. What am i doing wrong?



  • not sure,perhaps its to hot without ventilation or perhaps changing temperature to sudden.

  • There's really good advice about how to grow penstemon seedlings on ehow.

    Penstemons need light, free-draning soil and should not be watered much, although not allowed to dry out. I just wonder whether the heat from the lights, together with the water in the compost, made it too warm and humid for them.

  • nutcutletnutcutlet PeterboroughPosts: 26,845

    Penstemons germinate very easily without artificial assistance, maybe they thrive on a harder lifestyle. 

  • cairnsiecairnsie Posts: 388

    They germinate no probs maybe i am overwatering them. Thanks for the help i still have quite a few alive with there seed leaves ill just plonk them on the windowsill and see what happens

  • cairnsiecairnsie Posts: 388

    Thanks for the help

  • cairnsiecairnsie Posts: 388

    I tried again same happened this time kept soil much dryer still used lights so i guess it must be lights will try to use normal light from windows with this next batch. Its says on the rhs website to sow in a coldframe has anyone done this. Its weird there failing i have grown lots of different plants and they have all done well.

  • Liz 9Liz 9 Posts: 2

    Hi, I am having exactly the same problem as you so would be interested to hear how things progress.  I am growing Penstemons on the windowsill (no artificial light) and they are germinating then dying off as seedlings (don't think I've allowed them to get too dry or overwatered).  Other seeds are doing fine.

    Wonderd if it was getting too cold in the evening so will attempt to re-locate new batch at night if this new batch geminate.  Interested to hear your comment about planting in a cold frame so might sow a few more today and try them out in a cooler environment as a test to see if I've been killing them with kindness!

  • I do this, Liz. I have a dedicated spot in the kitchen where I put seedlings overnight, away from windows. An alternative is to cover them overnight and I'm also trying that this year.

  • P.S. They grow quite easily from cuttings if you already have penstemon plants.

  • cairnsiecairnsie Posts: 388

    I am onto my third set this time not using any lights just the windowsill. I dont think its temperature fluctations as my spare room keeps a constant and the lights kept the seedlings warm. They were fine and got to the point of just producing there true leaves and died. I have cuttings of penstemon and they doing fine. I figured it was the lights scorching the leaves, perhaps your window has too much direct sunlight as I kept my first set of seedlings very moist, the second set on the dry side so its not moisture levels. My third set have not yet produced true leaves. The leaves just shrilveld the actually seedling stayed upright for a while after this before dying so I dont think it was damping off. I am hoping this set will survive i will see. Another one of my theorys was the soil wasnt deep enough so this time i have sown them in small pots. I have been successful with a wide variety of other seeds so I dont understand why I am having trouble.

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