How to Grow Pacific NW Native Plants in Outdoor Containers


Although native plants will always do best in native soil with light, moisture, soil, and associated plants as close as possible to what nature intended, many people have microscopic yard space or just a porch or balcony. With a bit of planning and time, quite a few Pacific Northwest native species can successfully be grown in pots or other containers. Some — like drought tolerant sedums — may also be grown on green roofs.

When trying to figure out which plants might do best in your situation, consider which plants are native to your area. Then, take into account each plant’s needs and its natural environment, not just its physical appearance. For example, if you love maidenhair fern, which generally is a forest dweller that typically grows near streams or misty waterfalls, you know you’re going to need to supply a damp, fairly shady environment with soil rich in organic matter. Conversely, flora that typically grows in tight spaces — like rock crevices — may do well in sunny spots with fast draining soil within pots that aren’t terribly large.

If you’re thinking of grouping plants together in huge containers, remember that in Nature plants aren’t often found growing immediately next to another species, and those that grow quickly may shade out those that don’t. To help along container-mates, give them enough space and choose species that have the same needs (same light, moisture, and soil type) and that would likely grow together in nature (plants known as “associate species”).

Some ideas
For bright situations, try perennials such as yarrow (Achillea millefolium var. occidentalis), blue-eyed grass (Sisyrinchium bellum or S. idahoense), nodding onion (Allium cernuum), monkeyflower (Mimulus spp.), sedum (Sedum spp.), camas (Camassia spp.), hairy manzanita (Arctostaphylos columbiana) or bitterroot (Lewisia columbiana), the latter two with sharp drainage.

Partly shaded containers might grow Douglas iris (Iris douglasiana), tiger lily (Lilium columbianum), leopard lily (Lilium pardalinum subsp. vollmeri), western columbine (Aquilegia formosa), alumroot (Heuchera spp.), or the penstemons that like some shade and moisture (Penstemon serrulatus or P. ovatus). In very large containers, consider shrubs such as mock orange (Philadelphus lewisii), or oceanspray (Holodiscus discolor), but remember to rehome them before they get root-bound.

For shady areas, choose piggyback plant (Tolmiea menziesii), foamflower (Tiarella trifoliata), maidenhair fern (Adiantum spp.), and deer fern (Blechnum spicant), and in very large containers, snowberry (Symphoricarpos albus) or evergreen huckleberry (Vaccinium ovatum).

Tips
Keep in mind that any potted plant will need much more attention than those in the ground. Your watchful eye and experience will tell you what works and what doesn’t, but for starters, here are some things to consider to maintain plant health:

~ Choose containers that allow plenty of room for root growth. Ceramic and clay pots are generally best, but keep in mind that clay pots can crack when subjected to excessive water and low temperatures.

~ Be certain your containers have a drainage hole. Never let pots sit in saucers full of water for long periods.

~ Plants that grow fairly deep roots are going to need a deep pot, but width may be just as important. Needless to say, plants with fairly shallow roots will be able to handle shallower pots.

~ Plants that tend to spread a lot, such as wild strawberry and western bleeding heart, may not be happy in a pot for more than a couple of years.

~ Choose a growing medium that suits the plant (preferably without peat as an ingredient). Plants that need moist, rich soil will appreciate the addition of extra compost, while plants that need to dry out between waterings will do best with fast draining soil (add small gravel, sand and/or perlite to facilitate drainage).

~ Group potted plants with similar needs together to make watering easier.

~ Keep plants — even those that like quite a bit of sun — out of scorching sunlight during the hot summer months because pots will dry out very quickly, especially if they’re in clay pots.

~ Arrange larger pots in the center, with smaller pots at the edges, being aware that small pots may need more shade since they dry out more quickly.

~ Repot plants every few years to keep them healthy and growing. Donate those that have outgrown your space to someone with a yard, but try to do it before their roots are fatally confined (“root bound”).

~ Protect plants from freezing temperatures and excessive wind. Potted plants’ roots are subjected to much colder temperatures than those growing in the ground, so during sub-freezing temps place them in a protected spot or bring them indoors or insulate their roots from damaging cold and wind during wintertime.

~ Never dig plants from the wild, for two reasons: Usually the plants won’t make it and you’ll end up with a dead plant, and stealing from what’s left of the natural world is unethical. Please purchase plants from reputable nurseries or grow them from seeds that are obtained responsibly.

Heuchera micrantha (‘crevice alumroot’ or ‘small-flowered alumroot’)


© 2020 Eileen M. Stark

2 thoughts on How to Grow Pacific NW Native Plants in Outdoor Containers

  1. I’ve been growing a vine maple in a whisky barrel planter for many years. I just keep it trimmed like an oversized bonsai and it has remained very healthy and vigorous.

    Reply

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