Sleuthing in the garden-rhododendrons

Gardening involves a lot of disappointments (I promise I will end on something less depressing!). You have visions of how well a plant will do in the garden and what things will be like and then….the plants don’t cooperate. Sometimes they sit and sulk for years just limping along looking pathetic and forlorn. Sometimes they do surprisingly well and you think things are going to turn out, and then the plant up and dies suddenly in a few days. What’s up with that? This post is about one group of plants that has broken my heart repeatedly over the years.

Rhododendrons. I really, really want to like rhododendrons. I want them to thrive in my Pacific Northwest garden like they do in everyone else’s yard around here and bless me with an abundance of beautiful foliage and spring flowers. But, they don’t. I amend the soil with compost and bark mulch, or not. I fertilize constantly with an acidic fertilizer, or not. I water them, pamper them, coddle them. But, the fact is most of them just sit, and sulk, then slowly die over time. Here is our view out our dining room window. There is a rhododendron (just barely visible as a few pink blobs to the right of the trunk in the middle of the picture) that has been “growing” here for 10 years.

That’s it. Here it is, closer. I like looking out that window as I mediate in the mornings and seeing the bright purply pink flowers this time of year. It’s our native western rhododendron (Rhododendron macrophyllum), so it should do well here right?

Yet, upon closer inspection, not all is well. The leaves are a chlorotic mess. It’s under a grand fir (Abies grandis) and it is one of the few plants that gets watered consistently in the summer. It receives a yearly natural mulch of fir needles (acidic) as well as an annual application of compost. I have also fertilizes it like heck over the last few years with rhododendron fertilizer. It should be happy. Yet, after 10 years in the ground, I can only conclude it is not. This may be its last year on earth. I’m tired of looking at its ugly leaves for 12 months of the year for only 2 weeks (if I am lucky) of flowers.

Ugly! Not to mention many of the leaves have been notched by root weevils. I am guessing that they came in on this plant when I bought it from the nursery.

At first, I thought it probably had Phytophthora root rot. Maybe it was in the beginning stages of infection at the nursery and wasn’t showing symptoms yet when I bought. A light infection can lead to interveinal chlorosis (yellowing between the leaf veins) like this. Yet, after buying probably 30 rhododendrons over the years from a bunch of different nurseries and planting them in several places around the yard, I no longer think this is the case. I think it is something more fundamental.

Last year, my husband decided to install a hydroponics system in our dining room to grow houseplants out of reach of our cat. As part of the process, he tested the pH of our well water. Horrifyingly, the pH of our water was 10. 10! That’s like watering with a liquid that has the pH of milk of magnesia or a mild detergent. Not good for a plant that wants a pH less than 7. No wonder my rhododendrons do so poorly! Rhododendrons like acidity, not alkalinity So, I will be sending two soil samples, another well water sample, and a stream water sample in to be tested for pH this week. I am guessing our underlying soil is highly alkaline and that might explain why rhododendrons struggle to do well here. There also aren’t any natural populations of rhododendrons within miles of our property, so that provides another clue.

The next question is, what can I plant in its place? Once I rip it out (after blooming) I want something low maintenance, it will have to deal with dappled shade, dry summer soil, neglect. Color would be nice, but will have to give some thought to what will look good outside of the meditation window.

Why hello there! Look what popped up in the gravel next to our compost pile! A false morel – I’m guessing a Verpa species of some sort.

And, returning to the south stream garden. Two more native species that are doing well here: Oregon goldthread (Coptis laciniata). Supposedly needs consistent soil moisture, but this one has done fine with little to no supplemental water in the summer. The soil underneath literally cracks apart when it dries out, so I was surprised at how well this has done. Maybe it sends roots down far enough to reach the moisture (it is less than 30 feet from a stream, but also quite a bit uphill)? Maybe it is more dry tolerant than suspected? Either way, it’s a win for me. Hasn’t bloomed yet, but I really like the shiny evergreen leaves.

Devil’s club (Oplopanax horridus). Love this tropical-looking, big-leaved spiky plant. I want more! I have been trying desperately to get the seeds to germinate since it started blooming and setting seeds two years ago. But, they don’t germinate even with stratification (winter chilling). I wonder if they are self-infertile?

The false lily of the valley is starting to bloom. If you can get close enough, the flowers are surprisingly sweet smelling.

Non-natives in this garden. Persicaria ‘Purple Fantasy’. Keeping an eye on it in case it becomes too aggressive and invasive, but so far so good. Moderate spreader here. Great foliage.

Persicaria ‘Brushstrokes’. Clumper, not at all invasive. Great foliage. So far only needs minimal summer water (deep soaking once very 2-3 weeks).

Persicaria ‘Langhorn’s Variety’. This one worries me a little. Spreads somewhat rapidly and pops up in places 1-2 feet away. Keeping a cautious eye on it, ready to rip it out if it becomes too aggressive.

Eastern U.S. native, bellwort (Uvularia grandiflora) doing well here. Summer dormant.

Past their prime now, but here are some pictures of common cowslip (Primula veris ‘Sunset Shades’. Come in a range of colors from yellow to orange to red to almost reddish purple. Survives, though doesn’t look great, with no supplemental summer water, but returns and looks fabulous every spring. My favorite primula. First image is actually from the north stream garden, which receives afternoon sun. The south stream garden gets morning sun or none at all.

So, how are your rhododendrons doing? Any ideas for colorful, low maintenance replacements? Right now, I am thinking of trying some flowering currants (Ribes sanguineum) or gummy gooseberry (below, Ribes lobbii), for which I have an abundance of seedlings to try out.

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