You want sassy borders? 

Divide and rule!

– Here’s how.


While shrubs can be the back bone of the garden

and annuals offer seasonal pzazz, 

herbaceous perennials can make your borders really sing long term.

Even in the autumn and winter they can have stand alone, sculptural presence.

This is really not a ‘how to garden’ blog. We specialize in garden design after all. But there is little point in having a great design if you can’t manage the basic horticultural steps and your plant husbandry doesn’t cut the mustard.So occasionally we throw in some technical stuff to make that easier for you!

Now is about the last chance saloon for herbaceous division before spring grips. Here is our take on how to set about it:



The secret to good herbaceous displays is division and distribution.

You may divide for health reasons. While some plants don’t need dividing for years others get hollow centres and decline in vigour. When you do divide these, it should be done extra carefully, as though applying a tonic, so that it gives less lively plants a kick start. I am apt to discard any weak stuff in the centre of the clump.

But dividing also gives you the chance to make changes. The secret to a classic border is where you place the plants. During the year I usually have thoughts about border changes as I walk about the garden, and then forget them. I know in theory we note these down like the books say- but who actually does? And who can make head nor tail of indecipherable thoughts such as ‘Something tall and yellow at the back’? 

So come the start of the great move –  for timing see below –  it can all feel a bit like you’ve lost the plot.Getting out in the border gives you good ideas about this and so sound border work can be very much part of design development. And once you get going the thing does get hold of you and the ideas and the enthusiasm mounts.


Plants I find I always need more of are Siberian Irises, Phlox ‘White Admiral’ , and almost any Hemerocalis you care to mention. There are others and you will certainly have your own favourites.

Aside from plants which look  like they need it, I am often tempted to expand certain drifts. And usually to elongate them. I also quite like to have spin off plants from drifts which then achieves a more natural look to the border. I do also like to try new combinations.

And plants which I really love do end up in other borders when I am renovating them. I try to renovate at least one border a winter.  This use of similar plants around the garden helps to bring things together, so that you have a pronounced look or theme to the garden, rather than a collection of individual tableaux.


The aim in all division is for the plant to settle down quickly and get established. Cool, but warming helps this. So, this division thing is best done when the plant is dormant.

While, in theory you can divide plants the year round, you could be building in a high support requirment if you divide outside dormancy. Because they will need additional watering and may need nurturing for several years.

Divide in the Autmn through to late winter and you may not even have to water them in. Leave it too late and you will be caught in one of those dry hot spells we sometimes get now in the spring.


I am sure we have all seen the tv presenters dig clumps out of the ground with a fork and lever them apart with two forks placed back to back. I must say I haven’t done that for years.

I quickly found that the easiest way was to dig up with a spade and chop the plant apart with the same spade. (This spade should be sharp, worn to a razor’s edge by years of back breaking work! A border spade with a narrower blade is a good idea. Personally I would never work with a trowel since it knackers your wrists. )

Usually I lay the plant on its side and chop up from the base of the rootball to the crown. For me this achieves a good clean division rather than two great masses of shaggy and damaged roots. By all means divide and subdivide, but do not be too greedy. This just weakens the plant which then needs more support. In all this I am assuming you have cut the plant down to ground level before doing it. If I am moving in the growing season to ease its establishment I chop down by half.

When replanting always ensure that the hole you dig is one and a half to two times the size of the  rootball. I like to add some fortified compost of some kind worked into the base of the hole. Do filter friable (I like that expression!) soil down around the rootball of the plant leaving no pronounced air spaces. Do plant so that all the roots are covered. Obviously you could plant too deep, but on the whole deeper is better than shallower. One of the best ways of torturing a herbaceous plant is to plant too high.

You may or may not need to water in depending on soil dryness.


During the following growing season anything which I have divided over winter is always on my watch list. Really just for dryness. Do be aware that during dry spells these plants may need that support. If you have moved heaps then you will be praying for a wet summer!

Go have some fun and change your garden. I figure the next month is about the last chance we will reliably have to do this!