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Simon 707Simon 707 Posts: 3
I am having trouble with keeping delphiniums over winter. I will sow and plant them and have a nice plant for that year. For some reason they will disappear,root and all, with no trace what so ever. I have a heavy clay soil but I improve the soil every year. Is it because I am using a tender variety? 


  • fidgetbonesfidgetbones Posts: 16,536
    In heavy clay soil, it sounds like they are rotting off over winter.  Mine are in sandy soil. My main problem is slugs shearing them to the ground as soon as they emerge. I surround the plants with crushed baked egg shells to try to deter them.   You say you have a tender variety. What variety is it?
  • LynLyn Posts: 21,375
    I never plant delphiniums out the same year as they are sown, keep them in, sheltered for the first winter, keep potting on until you have a big plant then plant out in April or May the following year.
    Slugs will clear them to the ground so they need some protection there. 
    Gardening on the wild, windy west side of Dartmoor. 

  • marieS24marieS24 Posts: 23
    Sorry to interrupt but when should I start my delphiniums? I’ve never grown them before but recently purchased some seeds. Sorry again and thank you. 
  • Simon 707Simon 707 Posts: 3
    Mine are Pacific giants, but I don't think these are particularly hardy being in Yorkshire.  I always keep them in the green house for a year before putting them out. 
  • Jason-3Jason-3 Posts: 372
    I don't think hardiness is a factor. Most delphiniums actually need a cold winter to do well. They are in essence an alpine plant. 
    I have loam-clay soil and they generally do well.
    As others have said, you need to establish them in pots for one season, before planting out. I have ornamental bark in my borders, slugs seems to deter the slugs
  • purplerallimpurplerallim Posts: 4,694
    I'm having trouble with delphinium this year. Mine have been in three years, in clay soil, surrounded by slate and doing fine, until now. This year one failed to appear and the other is a weedy version of itself. No idea what variety just that they are pale blue.
    This year I have bought plugs of blue and white bee? so should I have not planted them this year?
  • Jason-3Jason-3 Posts: 372

    Dependent on variety, some delphiniums only last for 3-5 years max. I treat them as a short lived perennial and have half a dozen backup plants in pots
    I love delphiniums but they are a faff at times. 
  • PosyPosy Posts: 3,601
    If the clay becomes water-logged, the delphiniums will rot. Even when you have improved the soil, it can become water-logged. If this is the case you can build up the soil so that you are planting three or four inches above the original level. This is usually enough, BUT do watch out for slugs. They will eat emerging shoots before you can see any growth!
  • purplerallimpurplerallim Posts: 4,694
    True @Jason-3 they do need tlc, but I like them in spite of this. Will just have to get some more.😁
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