Foam flowers died

Asked September 28, 2020, 2:48 PM EDT

Thank you for your help. All of the foam flowers planted in this location did very well through the spring and early summer, but died off mid-summer. This location faces north and gets a lot of shade at certain times of the year. It gets much more sun in the afternoon during the summer from the west. The coral bells we planted in this location (which had alternated with the foam flowers) did fine through the summer. Some of their leaves turned brown, but they are still in good shape overall. We had our yard graded a few years ago, so the water drains away from this area to another part of our yard when it rains.

Montgomery County Maryland

5 Responses

Afternoon shade is just fine (ideal, actually) for Foamflower (Tiarella), but they do need good drainage. Does this site get watered often or does it catch drainage from a downspout nearby (even if it continues to drain elsewhere)? Many modern varieties of Coral Bells (Heuchera) are complex hybrids between various North American natives, some of which occur in habitats cooler, wetter, or drier than ours; this may explain why the Coral Bells, despite being a close relative of the Foamflower, are doing ok while the latter was lost - they have an adaptive advantage due to their diverse heritage. Locally-native Foamflower occur in wooded habitats, often in cooler areas like mountain foothills or slightly higher elevations. We cannot tell if overly-wet or overly-dry conditions contributed to the loss of the Foamflower, though they will likely not recover. (We see a bit of basal growth on one, but it looks weak.)

You could try again, or opt for another shade-adapted perennial instead. Japanese Painted Fern (which would harmonize with the Coral Bells foliage colors) is one option, though almost any fern will do if it fits (some get much larger than others). Japanese Forest Grass (a.k.a. Hakone Grass, Hakonechloa) is often used in combination with all of the above plants in shade gardens, though the spacing here might be a bit snug for a full-sized mature plant to fit in the future unless it is offset in a row slightly in front of or behind the Coral Bells. Fringed Bleeding-heart (Dicentra eximia) is nice in that it blooms for far longer than Old-fashioned Bleeding-heart, stays shorter, and does not go summer-dormant. If not too dry, Astilbe give a fern-like look with summer flowers.

Miri

The picture I shared is actually not very good, because it shows the area as shaded, which it is right now, but not during the summer. In the summer time, this area actually gets a lot of sun in the afternoon when the sun is higher in the sky. The foam flower seemed to do much better when the area was more shaded in the spring. The very small growth you are seeing now from one of the plants occurred just recently when afternoon shade returned to the area. Hence, I was thinking that the afternoon sun was the culprit. I was thinking this might be the case for the coral bells in my other post as well, since they get much more midday sun during the summer as well. Of course, the coral bells in the picture I attached to this post are doing fine, but they don't get as much midday sun. They mostly get afternoon sun. Could also be the variety of coral bells I suppose. Would you please let me know if you still think the moisture level might be the primary culprit after reading this follow up response. Thanks!

Ah, then this location may have been to hot and sunny for the Foamflower to prosper, as you suspect. Coral Bells are close relatives to Foamflower and also appreciate (and often require) afternoon shade to some degree. Nurseries that grow these plants for sale at garden centers use shadecloth over the crops to protect them from the brunt of summer sun.

Moisture issues are often suspect because their effects are so systemic and more drastic than leaf burn due to light levels. (One such symptom to look out for is if only leaves exposed to the most sun are effected, or all of them. Leaves shaded by growing underneath others should look healthier than sun-damaged leaves if light is the main culprit.) Root health is critical to the health of foliage; when roots struggle, the top growth loses its reliable supply of moisture and nutrition, and can easily and quickly desiccate or decline. This can create a negative feedback loop, because with plant hormones, the top growth stimulates root growth and root growth stimulates top growth. It's a mechanism intended to keep the two in balance with each other. When a plant gets out-of-balance due to dieback in both areas (say, dying roots causing dying leaves), it can sometimes weaken the whole plant because it does not recover easily with both hormone-producing tissues not able to function.

Unintentional over-watering is a very common gardening mistake; even experienced gardeners do this from time to time. Under-watering is also possible, and frustratingly, the symptoms of both look nearly identical when viewed above-ground. This is why monitoring the soil by literally probing down a few inches - where moisture levels change less rapidly and are therefore more trustworthy indicators of conditions in the root area than just looking at the soil surface - is very helpful in lessening the risk of over- or under-watering.

Foamflower and especially Coral Bells are sensitive to planting depth as well - if planted too deeply, they are much more prone to rot when conditions stray to the overly-wet. Growers are even cautioned by the breeders of these varieties to not set them too deeply in the pots when young plants are being potted-up. Having some of their rhizome - the stem thickening at the heart of the plant where leaves and roots emerge - slightly exposed at the soil surface is preferable to it being totally buried in soil.

Miri

Ok, I think I had multiple issue contributing to their demise. The coral bells that were not exposed to as much sun generally did better, but I also didn't know about how best to plant them and would have covered all of the rhizomes under the soil, which was apparently the wrong thing to do!

That's ok, even wholesale nursery growers sometimes need remining about planting depth for this group of plants because they are accustomed to a standard planting technique (for efficiency) that otherwise isn't always adjusted from plant species to plant species. As it happens, Iris are another genus that don't like their rhizomes covered with soil, though some other unrelated rhizome-forming plants are perfectly fine with this - it varies, as with many things in nature, depending on conditions the plant is adapted to grow in.

Miri