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Planting Under Trees - Part 9

© Marge Talt

 Last week, I started telling you about a relatively new bed under a group of trees in my USDA zone 7 garden. As you may remember, the soil in this area is interwoven with tree roots, so I planted the woody plants using my "planting high" technique. Perennials were planted in the excess mix that sloped away from the woody plant rootballs.

 This series on planting in the inhospitable, rooty soil directly under deciduous trees is photo intensive, and this article may be slow loading for many of you. Your patience is appreciated.

Some Happy Campers and Some Not So Happy

 Next to the Rhododendrons I described last week; still on the east side of the tree grouping, are three Astilbes. Until it died, the year before last, during a drought, I also had the lovely late blooming Kirengeshoma palmata. Astilbe 'Glow' (glut), Astilbe simplicifolia 'Sprite' and Astilbe 'Granat' have hung on for several years. This year, they are distinctly unhappy and I hope I haven't lost them altogether. It's been the driest summer on record, after a rainy spring, and despite copious watering, the moisture lovers are suffering all over the garden. I am finally getting it through my head that I can't keep Astilbes happy directly under trees unless the soil is very heavy and retentive. They simply won't do in the light mix I use for planting high. In very retentive soil, they will exist for years, but I wouldn't say that they grow well. These are really plants for that soggy spot or the banks of a pond or stream.

 In front of the sad Astilbes, and to the right of the Rhododendrons, Azaleas and Itea is a huge old clump of Hosta sieboldiana that I grew for years in my holding bed before moving to this location. It has prospered and grown even larger. You can see the trunks of two of the dogwoods (Cornus florida) to the right and rear of the hosta. This summer, it's not looking quite as well as it does in this photo, but it's holding its own. I'd guess it's something over three feet (1 m) in diameter now.

 To the right of the hosta and in front of the oak (Quercus) is a group of candelabra primroses (Primula japonica spp.) that I think I grew from seed. I really cannot remember where I got them. They have stayed with me for several years, but belong to the unhappy camper group. I simply cannot provide these plants with enough water to keep them happy. I love Primulas, but providing most of them with the kinds of conditions they need is tough. I'm in the process of making a damp bed - sort of a quasi bog - and intend on moving these unhappy plants as soon as it's finished.