Why are the leaves turning yellow on my clematis vine?
What is happening to my clematis vine? It has yellowing leaves. This is the second year in a row with the same problem.
There are several potential causes for yellowing in clematis foliage. The only pathological cause we would typically worry about is tomato ringspot virus, but it generally produces a more mottled/spotted effect, as opposed to the rather uniform bright yellow you have. Another possible cause is a magnesium deficiency, which can lead to yellow leaves, and I would recommend a soil test from the UMaine Extension Soil Lab to rule it out completely.
However, I think what you’re looking at is the impact of overly wet soil. Clematis is well-known for being temperamental about wet roots, with the excess water interfering with nutrient uptake, and the rainy spring we’ve had combined with compacted roadside soil may be the culprit. There isn’t much you can do there short of lifting the plant and transplanting it into a large planter or amending the soil, but if this is the cause it should get better as things dry out (and you certainly shouldn’t do extra watering until we hit the hottest, driest parts of summer). I would also recommend a nice layer of mulch (as well as any other shade available) later on in the season to protect the roots from getting too hot, another thing clematis can be picky about and that can result in issues the following season.
It’s also theoretically possible that you have some frost damage from early emergence and cold temperatures, but if that’s the case the remaining growth this season shouldn’t be affected.