I should clarify that the browning started early in the season,even when they were well watered.It is limited to the bottom half of the plants.

I don't know but I get it too :(

Can also be attributed to uneven watering.......may be plenty of water at one time but allowed to dry too much in between.

my recollection is that its not really all that uncommon ... accept it for what it is.. or replace it ...

btw.. maybe a camera pic.. but they look very tall for phlox.. if peren is correct ... ... could fert be an issue???

also.. seeing the brick edger ... if there is pavement further out.. you could have been cooking them at some time during the growing season ... reflected sun or heat .... perhaps when you missed a watering or some such ...

fianlly.. plz add your location to your name on your member's page.. frankly .. this what what plants start to look like in sept in my z5 MI ... they get tired and ugly ... especially the oldest.. lowest leaves ... especially when i was lucky enough to have 2 long droughts this year ..

ken

ps: also a good mulch will keep soil from plashing up on plants.. and that is often a vector for other problems ... regardless... that thing looks healthy as all get out.. and i wouldnt even have noticed that part.. i were visiting your garden ... ignore it ... stick your nose in the flowers ...

I'm with Ken - some plants just do this at the end if the season. If you think of it, they're not really getting all that much sun on the lower leaves, why keep them? Of course, they can't know they are ruining our esthetics!

This is a plant I won't grow (ever again) because of its tendency to attract many kinds of diseases. Since you said that this started early in the season, I'm going to attribute it to a simple fungus or mold. If you look at pictures of garden phlox, you'll find many examples of exactly what yours look like.

Do yours also end up with a bad case of powdery mildew, too?

Powdery mildew on phlox has been a constant problem for me in Central Mass. This year I was proactive with spraying the foliage with a 1 part milk (I used skim) to 9 parts water solution. Started before the mildew AND after mildew had formed (different plants). Worked wonderfully!!! I had very few phlox with the PM, and applied it a couple of times a week generally, until I got lazy. Plants I had been fairly faithful in treating are still mildew-free.

I was surprised that such a simple solution worked so very well. Will do this in future for sure....

As to your original query, I find that phlox and asters usually do the lower leaf browning. I haven't figured out why or what to do about it, so just live with it.

Phlox are one of the more frustrating late summer plants for any of us who cannot provide the lush moisture they need (and for those of us too knackered to consider watering stuff in the ground). I certainly don't bother and gave up on them after many attempts (although there are a couple still hanging in there, looking wretched).

Always surprises me with Phlox paniculata, that some folk have problems with powdery mildew (at least in our sort of growing environment). From mid July on, we have a back garden (almost) full of these phlox, but, to my knowledge, have no powdery mildew on them.

My feeling follows that of David Tomlinson, (Merlin's Hollow); namely that powdery mildew is a disease that healthy phlox are able to fight off themselves. They just need appropriate growing conditions in the garden environment (again I'd emphasis in the type of garden environment which it's possible to maintain here).

In the case of our own small garden, I'd also credit attention to garden hygiene as well; notably to cutting down all summer and fall blooming herbaceous perennials to ground level and removing all plant debris by the end of the growing season. Presumably that greatly reduces overwintering by the disease organisms themselves.

Re recent comments, I've now seen powdery mildew on two of the three beebalm cultivars which we have. I did cut the affected parts out immediately (the same as I used to do, in years past, with the phlox), but powdery mildew seems to be relatively species specific as you read.

Correction to the previous post: Did see the beginning of powdery mildew on a few phlox today as I was cutting phlox back. It was on leaves high up on the stems. In the past, when I used to see more of it, I thought it was located on leaves lower down on stems.

Anyway, cut affected parts out and sterilized the scissors with mouthwash.