Report: Black Walnut Rose Plantings
Some months ago there was interest in what roses might grow beneath black walnut trees. People on the rose forum reported that hybrid musk roses were tolerant of the juglone toxin emitted by the Black Walnut Trees. Since I am surrounded by Black Walnuts (9) and love roses, I took the challenge and planted several roses. I already knew that Rugosa Roses are tolerant as I have these growing near one of the monsters. Also, multiflora roses are reported to be tolerant, and I have observed this in my part of the country, Pennsylvania. Therefore, I have also planted three multiflora hybrids, Paul's Himalayian Musk, Russelliana (Russell's Cottage Rose) and Veilchenblau. These were planted last spring and fall.
The hybrid musks planted this spring are:
Sky rocket, Daybreak, Bouquet Parfait, Prosperity, Lavender Lassie, Erfurt, Ballerina, Penelope.
One rugosa sucker from my rugosa rose bed was also transplanted here: Martin Forbisher.
These roses were planted in amended soil about 4 to 6 feet from the trunk of 2 very mature BW trees. Ones planted this spring were mainly own root roses, others are on multiflora root stock. The new babies did not receive any fertilizer until about two weeks ago. Others received spring fertilizer and again about two weeks ago. The fertilizer consisted of compost, holly tone and alfalfa meal. They are sprayed about every 14 days with the Cornell Formula (mainly horticultural oil and baking soda) to control pests and diseases. Here are the results:
None of the roses have croked. All are leafed out and some are blooming. Only two that arrived with bad cases of black spot are showing very minor infestions of black spot. The best performer so far is Erfurt with the most blooms, healthest leaves and most growth (although Penelope is quickly catching up). Veilchenblau is showing stress on the tips of several canes. I prune these back to healthy wood. She is blooming well on all unaffected canes and continues to grow
One hybrid musk (Andenken an Alma de l'Aigle) was planted in a "safe zone" at least 75 feet from any black walnut tree. It was a two year own root-most were one year own roots- and it looks no healthier, nor has it bloomed more. It has some black spot on its lower leaves.
This, of course, is just the beginning. Sometimes it takes several years for a plant to show the signs of juglone toxicity. So far, so good.
I have other plants as companions scattered about, but these all appear on one list or another for tolerance to juglone.
I hope some of you have found this interesting.