Perennial Dianthus - When should I divide them?

I have some really gorgeous dianthus that did just ok last year. This year it’s going berserk! The two red mounds are squeezing out the pink one in the middle. Can I divide them right now in the beginning of the season? If so, exactly how do I do it? Can I just chop it in half and re-plant them or is there a trick to it?\

Thanks!

You don’t divide them. You can move them farther apart or even trim off some of the branches. They still all connect to a central root system.

I’m not sure what distinction you’re drawing here –

Kalhoun – if they’re growing in clumps, you can divide a clump by stabbing a spade right through the middle of it. Take half the clump and move it elsewhere, then fill in the hole you left with a few handfuls of compost. Water the clump you move regularly while it gets established.

Now is fine, if it isn’t too hot where you are yet (July and August are bad months for such projects) – otherwise wait till Fall.

This reminds me of an aphorism about planting perennials that I learned in my Master Gardener class: “The first year, they sleep. The second year, they creep. The third year, they leap.”

Anyhoo, what Twicks said. I’ve found dianthus to be pretty forgiving.

I mean the clumps spread out but they don’t keep sending down roots as they spread. Maybe your speaking of a perennial dianthus variety I’ve never seen.

Kalhoun, as H. Dischord says, It does depend on which dianthus you are talking about. Photos would be nice to see the condition and type of plant.

In my experience, the gray-needled dianthus form a nice mound, but if you search around under it, the roots come from a rather small area. These can be rejuvenated by cutting them back hard, allowing new growth to sprout. This would also allow for the crowded plant to have some space.

The bigger-leaved dianthus will have more of a root area to divide, so more amenable to it, as per Twickster’s good advice.

I’m in the South, and we’re going into the hot months, so dividing is better put off til fall here at this point. You can divide anything when you need to if you keep up the care in watering, though.

Here is an excellent Fine Gardening online article on dividing perennials, complete with video demos.

:smack:

Duh, yes, of course there are two kinds – I apologize for my tone, HD. I’ve got the clumpy kind myself, and totally wasn’t thinking about the matty type.

Don’t worry about it, Twicks. Dianthus are notoriously evasive in their behavioural spread. They look like a big old clump, and ya’d think they would root in at the nodes like other perennials, and be easy to divide.

But, nooooooo, they are one of the 5% of plants in my nursery, in growing in a small pot, that I have to give extra finagling in figgering “WTF do I do with you NOW ???”, sense. Not to say they’re hard to grow in the garden; their drought tolerance and easy care make them worth all the finagling .

Great! It’s colder than a brass monkey’s ass here. I’ll do this some time today.

We have the broader-leafed ones. I’ll post a photo later today. Basically it’s a large clump of red, a squished clump of pink, and another large clump of red. It amounts to a continuous clump about 2 feet wide. I think I need to leave the squished pink, dig up each red and divide and re-plant them.

I heard a similar saying: "First year ‘survive’, second year “alive’, and third year ‘thrive’”.

I had a really beautiful one that I got from a greenhouse guy who was experimenting with them to get one with a really blue foliage. After the first year it was a pretty big clump and I decided to try something with it. I was building a rock garden and I thought it would be beautiful to have a complete bordor of this dianthus. It was August. I lifted the clump and seperated it into a couple hundred seperate strands and planted a border of about 25 ft long by 3 ft wide. It was good the following spring but by the second year it was magnificent. Deep blue foliage covered with bright pink flowers. It was such a big patch of them that the smell of them was almost overpowering. Even when not in bloom it was beautiful. All winter it held it’s colour and that’s in Canada where it’s not so warm in the winter.

That sounds just beeeautiful! Mine look really healthy and I’d like to try something really spectacular like that, but I have a really rough lot with little sun, and I just don’t have the time/energy right now to prepare a big-ass bed like that. Some day…

Dianthus are so easy to grow they’re my New Favorite Plant. I’m really glad Kalhoun had this question, though, because I probably would have just divided them instead of cutting back.