I was picking dahlias in the rain today. No choice sadly, it wasn't forecast so I didn't cut ahead and the florist was coming to collect this affternoon.

Last year, I found that I didn’t have enough white dahlias to supply complete wedding orders for all-white weddings. I needed to be able to reliably cut at least 100 white dahlias at any one time. So this year, I wanted to have more white dahlias of different styles and sizes. I bought some new varieties. I haven't really assessed them yet, as they have all been good so far. I have two varieties of white ball dahlias - one is Snowfllake and I think the other is Boom Boom White. I can’t remember which is which and the plants are so densely planted that its a real effort to find the labels. No matter, I’ve been cutting both happily.

Today, I noticed that one variety had brown markings as a result of the rain, but the other was fine. So….suddenly the non-marking one is the better variety. Otherwise they are equally productive, similar size and usability. Given that we’re likely to get rain in September in most years, I need to make sure that I keep the better one, and propagate more of that one, and get rid of the browning one. September is the perfect time to review your dahlias - decide which plants to get rid of, which to propagate from.

Brown markings on petals - this was the worst one, but all on this variety

I use a label code system to mark the plants. I know they have a cultivar label, but its not always easy to find until I come to lift them. So, to be easy, I have some coloured labels - Red for get rid, Green for best ones that I want to propagate from; blue for ok - keep, but not the best examples. This means I can easily go through them and push in a label at the base of each plant. Then when I come to lift them, I know which to keep in a ‘propagate’ box and which to chuck out.

This year too, I’ll be marking some to collect seed from. Paula Baxter has done this and inspired me to try it. For this though, I’ll be tying a piece of ribbon round the heads I'm keeping so I don't snip them off. See her blog before this one to read more.

Why get rid of any? A few reason:

Just poor examples - even plants of the same variety can be very variable. I have selected the best examples over many years, and I've got good sturdy plants that do well in my conditions, and with a flower form and colour that I like. They may not be true to type, but if I like them, then that’s more important to me - I'm growing them to to use, not to show. For example, we all know Wine Eyed Jill can vary from lilac to yellow. I’ve just kept the ones that stayed the best colour for me, in my conditions, and got rid of the ones which I didn't like. The white dahlias which turned brown in the rain will be in this category.
Ones I didn't plant and don't want - either I’ve been sent the wrong variety or some tubers were accidentally left in the ground and have come through winter, or wrongly labelled last year and I’ve carefully lifted, stored and planted the wrong plants.
Disease - I will get rid of any plants which aren't thriving. If they're not thriving now, they are unlikely to improve next year. In particular, I look out for yellow mottled leaves which is likely to be a sign of virus and take these out straight away and burn them.
Lastly, and perhaps most difficult - the varieties that I haven't sold, or aren't productive enough, or too short stemmed or whatever. Even if I like them.

Finally, I do a plan for next year. How many do I want to have of each variety, and what gaps or missed opportunities that I want to fill - for particular shapes/size/colour. Thats where the fun starts!