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Dividing Perennials

Hello - just needing some reassurance I am doing the right thing.

I am 2 years into 'making' a new garden. It is a large site & I decided from the outset that the only way I could afford to stock it full to busting with my beloved herbaceous perennials was to propagate a lot of them myself. 

I am growing a lot from seed & cuttings but also brought some prized specimens from my previous garden and purchased quite a few 'stock' plants last year.  I have loved & nurtured (aaah!) these last 2 groups of plants for the past 12 months & am pleasantly suprised that several are now definitely large enough for me to divide (primarily brunneras, hardy geraniums, dicentra, astrantias and thalictrums). They are all in the ground (ie not in pots).

I know that it would have been best to lift & divide them earlier (eg April) but I was a bit (ie VERY) busy planting shrubs and hedges at that time & the plants were also very late & giving no indication then of just how much they had grown in one year.

I am reluctant to divide them right now as they are all either in or about to come into flower and lifting them now means they will wilt and probably need cutting back - and they are currently doing a good job cheering up my rather bare garden no end!

I could wait until autumn but I garden on heavy clay and I know that small plant divisions are likely to sulk and rot if we have another cold wet winter.

I was thinking of waiting until flowering was over (when I would normally cut the plants right back to get a fresh flush of leaves) and dividing them then. I think the soil will be a bit too hard and dry for small divisions (not much rain in Suffolk again this year!) so I thought I could put the divisions in pots and maybe plant them out late summer if they've made enough root growth. If not I can sink the pots in the soil (saves watering) and plant out next spring.

I'd be grateful for some moral support if you think I'm doing the right thing or even more grateful if somebody could point out the error of my plans & prevent me making a big mistake and maybe losing a lot of plants.

Thanks in advance.

Heaven is ... sitting in the garden with a G&T and a cat while watching the sun go down


  • fidgetbonesfidgetbones Posts: 17,569

    I'd wait until next spring. When they start into growth take cuttings or split. You should be able to get seed off the thalictrums and even some hardy geraniums.  hardy geranium seed I sowed last spring, some flowered last year late on, and the rest(mixed packet) are flowering now. 

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  • nutcutletnutcutlet Posts: 27,411

    Most things will survive if you divide and cut back and put in pots in the shade. You do have to keep them watered through the summer though which is a bit time consuming if you've done a lot. As Verdun, I'd hesitate with the dicentra if it's spectabilis. But if it's one of the spreaders I'd go ahead

    In the sticks near Peterborough
  • TopbirdTopbird Posts: 8,322

    Thanks for your input guys.

    I agree with Fidgetbones that next spring is the right time for me to do all this but it is SUCH a busy time of year that I always seem to run out of days (& my OH likes to go away for 2 weeks in March / April which doesn't help in the least!!!) - which is why I would like to start the propagation this year.

    I agree that the brunneras & some of the geraniums are tough enough to withstand division in early summer when the flowers have finished - whether they go straight back in the ground or are grown on in pots will have to depend on the weather & soil conditions. Right now the soil is pretty baked & we could do with some rain (but not this weekend please as I'm having a girlie garden-visiting weekendimage).

    Some of the more delicate & precious geraniums are of the pratense and walliacanium varieties which I desperately want to keep so will probably give those a bit more TLC and divide into pots at the end of the summer.

    Fidgetb. - I have just sowed some mixed hardy geranium seed (purchased from Margery Fish's garden) - so I am excited to find out what comes up. Didn't realise I would get seed from the thalictrums as well as being able to divide - so that is really good news. I love these pretty plants dotted all over the shady areas of the garden with foxgloves to come a bit later & hardy geraniums round the bases.

    Re the Dicentra. It is the common spectabilis variety & I have seen conflicting advice about propagation of these.

    Some people say the roots are very brittle & the plant resents disturbance & it doesn't need dividing. Others say to divide in spring (or after the leaves have died down) or take root cuttings or to collect seed. I have 2 large plants - one in the right place & one that need moving now that we've rearranged some fencing and gates.

    So I think at the end of flowering I shall experiment with the one that needs to be moved but leave the other one be for now. Will let you know which method seems to work best.

    Heaven is ... sitting in the garden with a G&T and a cat while watching the sun go down
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