You didn’t give much information. What plants experienced wilt? Age? Cultivar? How long have they been in the pots? Size pots? Growing medium? Did you check for other causes? Often what is suggested to be wilt actually isn’t, and is caused by poor growing medium or watering issues or another disease or damage from wind or critters for example.

IME cultural practices will typically take care of algae, either removing it or topping pots with mulch or fresh medium.

Like GG48, I also haven’t had issues needing fungicides for clematis in pots. And by nature, I am quite cautious in using any type of pesticide preventitively as they can have unintended effects.

I was just wondering about this same question today. I have not experienced wilt in either my potted clematis or ones in the ground - but also wondered if using Physan 20 as a diluted preventative spray would be advised.

Why fix a problem you don’t have?

It is to the manufacturer‘s benefit to convince you that you need it, but it likely isn’t to your benefit.

The other issue is that they have yet to confirm the source of clematis wilt. The current premise is that there are two forms of 'wilt' - one (not very common) which is fungal in origin. Most clematis authorities have concluded that this is more of an issue under greenhouse/nursery growing conditions and seldom seen in home gardening circles. The second and likely most common occurrence is due to cultural issues....stressors that affect the growth of the plant and alter the vine's abilty to transport sufficient moisture and nutrients to the rapidly expanding topgrowth. The result is the wilting of the vine from the top down in the exact same manner as the fungal issue presents.

Neither one is fatal to the vine and cutting back the wilted portion and tending the vine as normal typically results in healthy regrowth.....perhaps that season but typically for sure the following one.

Since it is unlikely that the wilt most clematis gardeners encounter is fungal in origin, it seems premature and unnecessary to treat with a pesticide that will ultimately have no effect on the problem.

IME of nearly 50 years of growing literally many dozens of different clematis (and working for a wholesale clematis grower), I have never encountered a wilt with a fungal origin. Any vine that has presented with wilt-like symptoms - and these include many nursery returned vines supposedly "dead" from wilt - has been due to unfavorable growing conditions that placed the vine under unnecessary stress: insufficiently prepared planting hole, relying on a single vining stem rather than encouraging multistemming from the root crown, not planting deeply enough, drought stress, an insuffciently developed root system not able to support the topgrowth. etc. By correcting these planting-related issues, the vines recover and perform as expected. Pesticides of any kind are simply not required.

Thank you! I dont like using unnecessary chemicals anyway. I have not experienced wilt in either my planted in ground clematis nor my potted ones, so will leave well enough alone. Thank you for your detailed explanation!

Judith

I also have clematis in containers and have had no need to even consider treating them with fungicide or insecticide.