So do you think that the advice to divide perennials is for perfectionist
gardeners only? That's certainly what I thought I thought 'oh well you know
I enjoy things making a clump'. I didn't think I had to dig plants up, and of course I worried
that if I dug the plants up and divided them, I could damage them and then when I
put them back they wouldn't flower and I'd have a gap in the garden but that really
isn't something you need to worry about, and I'll explain why. It's Alexandra here
from the Middle-sized Garden YouTube channel and blog and we're talking
about dividing perennials today. So why do you need to divide perennials?
When you plant some plants like irises or dahlias or day lilies or phlomis,
or asters or ornamental grasses, you plant the plant in and over the
years the roots, the corms or the rhizomes clump outwards and so
you get a sort of ring of plants around the original plant, and then the original
plant dies off, so you get a sort of bald patch in the middle and that
gets colonized by weeds. But plants that do this can be quite aggressive, so they
may actually take over the space that you needed for other plants
in your borders. So some other plants die and in the end you've got a few really
spreading plants in your border but not many of the plants that you actually
chose. So the plants that don't need dividing are things like shrubs and
roses. You basically plant them in one place and they stay in that place - they
can get very big, they can even get too big for their spot, but they're not
going to go wandering off down the bed creating new colonies, and it's the ones
that go wandering off down the bed to create the new colonies that are going
to crowd other plants out. For example, day lilies. I dug out a huge number of
day lilies and divided them last March. I really need to do it again now so that's
why it's a good idea every two or three years to have a look at your perennials
and to work out which ones are growing into very large clumps or have a bald
patch in the middle and those are the ones that you want to lift and divide. So
a lot of people then want to know when do you divide perennials? Either spring
or autumn should be fine. If you're thinking about individual plants you
can check online for what the experts say and you'll sometimes find that they
say 'Oh divide them in autumn' or 'divide them in spring' but they don't always
agree and I think on the whole you're safe dividing plants in either spring
or autumn. The reason why you can't do them in either summer or winter is that
plants will be under stress if they have to deal with very hot dry weather or
very cold wet weather just after they've been lifted, cut up and divided, then put back
into the soil. So how do you actually divide the perennials? It really is as
simple as 'dig up the whole clump'. We've had a lot of very dry weather recently
so I soaked the soil around these iris sibirica before we were going to lift
them up. Even so I put my spade in and I really couldn't get them up at all, so I
got my husband with a bigger spade to get them up, and he thought that
I wanted to throw the plants away - that I was digging up because I didn't want
them. I went off to do something else and I came back to find him picking
the plants up, shaking really hard to get the soil off and then throwing them over
his shoulder, and they were all sitting in a heap on the lawn, and I have to
say that even that rough treatment has not done them any harm at all. The next
step that you need to do is to actually divide the plants and I looked at a lot
of videos and read quite a lot of advice, which said things like 'gently tease the
roots apart' - well there's no teasing of roots apart for iris sibirica, I can tell
you. I wrestled with the roots for about five minutes and got absolutely nowhere,
so the next step is to take a spade and you jam the spade down really hard and
you slice the roots open- and you will cut some roots but it provided there's
enough root left the plant will be fine so don't worry too much about damaging the roots -
particularly as when you're dividing plants you'll probably have about three times
as many plants as you want to replant so you have got some plants in hand. So I put
the spade down in the roots and I put my foot on the spade and then put all
my weight on the spade and absolutely nothing happened. And a friend tried as
well and all that happened was that we wobbled about on top of the spade and
eventually had to jump off before we fell off. So the next thing you can
do is use a knife and I did manage to get a few of the outer roots cut with
the knife and then I went back to the spade and in the end it was a mixture
between wrestling, spade, knife, wrestling, spade, knife and I managed to get three
clumps off this main clump of iris to replant. In terms of the size of
the clump you're looking for - cut away something that would probably be about what you would
buy in a garden center in a three liter pot. And then it's important to replant
it immediately - I have to say what I really wanted to do was to go to bed -
but I had to get them in immediately, so I did and I planted holes and you
need to plant the holes as far apart as the plants would be if had you just bought
them new from the garden center. So once again look up iris sibirica, for example,
on the internet it needs to be planted 8 to 12 inches apart, so I planted
three holes 8-12 inches apart. Then add some fertilizer - I threw in some blood
fish and bone, which the dog started to eat so I got the plants in really
quickly and back filled the holes and then watered it in. And you need to water
it in because this really gives the plants a very good start and also it
waters away the last of the blood, fish and bone and stops the dog eating it. So
which perennials need dividing? There are lots and lots of perennials that need
dividing - asters, symphyotricum, irises bergenia, geraniums often do, hellebores
hostas, day lilies. This is Nepeta here Nepeta Six Hills Giant - and it was
sprawling absolutely everywhere, so I dug it up and divided it last autumn (last
fall) and it's coming back beautifully, as you can see I'm afraid it's completely
surrounded by terrible ground elder which I've obviously got to dig up.
When I walked through my garden for this video I realized there were about five
or six different clumps of plants that had got far too big - this is bergenia,
and it's just finished flowering - it's got a lovely pink flower and this has
actually just completely spread so much - it doesn't seem to have a bald patch in
the middle, but that might be because it's growing against two walls. There
are some plants that come into the 'dividing perennials' lists which not
everyone agrees on, and one of those is peonies. You will see 'time to lift
and divide peonies' in some of the to-do lists but other experts say
'don't lift and divide peonies' and I think with this I would just go with
your instinct. The peonies in my garden really haven't clumped up, they haven't
grown, they haven't spread, they certainly don't have a circle and a bald patch, so
I don't really see any reason to lift and divide them unless I wanted to create
more peony plants. Dividing plants is a really good thing to do if, for example,
you're moving house- you could lift your plants up, put some of them in a pot and
take them on to the new home and then put the others back in the soil for
the next people to enjoy. When you lift and divide plants you'll have quite
a lot of plants left over so you can give them to friends or donate them to
charity plant sales but don't forget to pick any roots of perennial weeds
out of them and also don't forget to label them. There's a playlist of
gardening techniques I've put together at the end of this video, so if you're
interested in 'how to's then do look at that and let me know in the comments
below if there is any particular 'how to' you'd like me to tackle and if you want
more tips, ideas and inspiration for your middle sized garden, then do subscribe to
the Middle-sized Garden YouTube channel and thank you for watching, good bye!