I have been developing a hosta and sword fern area of the garden, and I am thinking it would be nice to have something interspersed between the hostas and ferns to add a bit more color, perhaps something flowering? Once the hostas and ferns are mature, it will be quite filled in, so I supposed something that doesn't need a lot of room? The area has some morning sun/early afternoon sun. Any thoughts? I am in Portland, OR.
I would recommend shade-loving or shade-tolerant perennials like astilbe, heuchera, dicentra. They will add beautiful colours to your garden.
You might be able to grow Roscoea purpurea in Portland....if so, it could work well in your situation.
What is providing the shade is a critical point, if the area is overhung by low-branching conifers - as would often be the case in Portland and the PNW/Coastal BC - then weevil-prone kinds of plants (there are many) are liable to be quite problematic.
Depending upon the types of ferns and hosta, and how much space is between the plants you could run into an overshadowing problem unless you plant something that is fast growing and very durable. As the ferns and hosta grow they will fill out and do a good job of smothering anything that is not fast growing and tall enough to reach over them. Many years ago I planted 2 areas - one with hosta (under cedars) and the other with native lady ferns. Over the years these plants have grown very well and filled in the areas, and in doing so have managed to smother anything else I've tried to put in to add color. Short of removing some of the hosta (which I don't want to do because its difficult finding things that will grow under cedars), what I have done is planted a lot of early blooming tulips. These flower very nicely and fill in the areas in the spring and while the hosta are starting to grow, and they finish about the time the hosta take over....and I do mean take over (some of mine are over 3ft in height and very full). I've also put in some nice large pots amongst the hosta (tall enough not to be overshadowed) and planted these with an assortment of colorful perennials that will show above. As for the ferns, the second area where I planted the native lady ferns also overshadowed anything else I tried to grow in the bed until I got aggressive this year and ripped out a large area that I will be keeping "fern-free". This area I have now planted with toad lilies and dog-tooth violets, as well as an assortment of windflowers
