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Hi I’ve got a number of Cerinthe seedlings all doing well and now in 3 inch pots. However I could do with more space for other seedlings  ( they are growing inside the house at a constant 18 degrees C under full spectrum lights) so I was thinking of moving them to the greenhouse which I keep at 10/12 degrees C. Will they cope ? I could also put them on a heated mat. Thanks. 


  • Hostafan1Hostafan1 Posts: 31,614
    edited March 2021
    Welcome to the Forum.
    I've got them self sowing in the garden and they're in active growth already. I'd say they'll be fine in a sheltered spot outside ( depends upon your garden  /  location ) 
  • pitter-patterpitter-patter Posts: 1,816
    As @Hostafan1 says, Cerinthe are hardy and they are fine outside. But yours would need to be hardened off for a bit.
  • Thanks.. I wouldn’t want to risk putting them in the garden just yet I am in the north east and it’s freezing .. but yes it sounds like I could put them in the greenhouse then 😊
  • Indeed - bit of an outdoor self-seeding 'weed', though they seem prone to mildew. I still quite like them. Am I right that you didn't used to see this plant in UK gardens - just the recent decade or two? I can't imagine it being cossetted at 18C under lights, as opposed to just getting on with it outside. They're not entirely hardy, so after growing all through autumn/winter, some stems got frosted in the recent cold February weather, but not fatally. Absoutely fine in a 10/12C greenhouse - still a bit 'soft' for them really!
  • Yes, they are a fairly new introduction to this country. I bought about 10 seeds at an exorbitant price about 20 years ago. Described as tender exotic and rare I still have offspring from the original parent plants. They self-seed everywhere and I have sent seed to friends in various parts of the UK and they are all doing well.I never lift the seedlings or give them any special attention other than to replant in a more suitable position. Once you have them in the garden you have them for life. I enjoy the unusual flowers and bees just love them. 
  • Hi there I have sewn some cerinthe seeds this autumn also in the unheated lean to. I would also like to clear space for more seeds I’m based in SW London and was wondering if you think they would survive being hardened off and planted out in January? I’ve not grown them before so am a bit unsure. Thanks for the advice 🙏
  • AnniDAnniD Posts: 9,624
    Hello Siobhan  :)
    I've found cerinthe to be pretty tough, l think your main problem would be wet rather than cold. They seem to collapse and go "mouldy" if the weather is very damp.
    Personally,  as you're in SW London, if you have the space l would tuck them up against the house wall and plant out mid to late March.
    Others may advise differently though  :)
  • Cerinthe is as tough as old boots. I would keep some seed back to sow in the Spring just as insurance.
    I bought a packet of seed at great expense 20 years ago as an unusual, tender plant. I have never been without them since. Despite moving house. They must have travelled in my containers.
    They come up every year somewhere in the garden, they seed themselve everywhere. I have never resown mine. I just weed them out where I do not want them growing. I have a couple of self-sown plants in flower at the moment. The colour combination is lovely, the only problem with them is the large size the whole plant grows to They  usually last for several years before getting rather floppy and brittle before the branches begin to snap off.

    It would be a good idea to keep the seedlings you have under cover this winter, greenhouse/cold frame etc. They do not need heat but protection from gales and hurricanes etc. some fleece or bubble wrap laid over them if we have freezing conditions in Jan.-Feb.
    Good luck.
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