How to Plant & Grow Obedient Plant (Physostegia virginiana)


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how to grow obedient plant around ponds
Obedient plant flowers are three-lobed, with the lower lobe acting as a bright “landing strip” for pollinators.

Obedient plant, also known as false dragonhead, belongs to the mint family, Lamiaceae. Like most members of the mint family, obedient plant is easily identified by a characteristic square, four-sided stem, and leaves that are arranged opposite one another on the stem.

The genus Physostegia is commonly known as the false dragonhead genus, so named because species in Physostegia closely resemble those found in Dracocephalum, the dragonhead genus (also found in the mint family, and more commonly known as the snapdragons).

Oftentimes, organisms evolve similar characteristics in tandem because they happen to work quite well. For example, all finches have broad, cone-shaped beaks because those work best for breaking open seeds, but not all finches belong to the same genus or even family.

And so it is with many plants – obedient plant and snapdragons have evolved very similar flowers to achieve similar pollination purposes and results. Obedient plant in particular has very mobile flowers, which allow each individual flower to essentially be “pushed” into any direction one chooses, hence its name.

Facts, Benefits & Uses of Obedient Plant

Obedient plant benefits to garden ponds
Obedient plant draws in a variety of helpful pollinators, including bumblebees and butterflies.
Top: Helena Jacoba / CC BY-SA 2.0 Bottom: KS Black / CC BY-SA 2.0

There are 12 species of false dragonheads found in North America, of which the obedient plant is the most well-known and is considered highly desirable by many gardeners and naturalists. It is not native to the UK, India, or elsewhere aside from North America, but is nonetheless a popular garden plant around the world due to its beautiful flowers and fragrant, minty leaves.

Obedient plant’s flowers are three-lobed, with one large lower lobe that acts as a sort of bright, beckoning landing strip for insects. This flower structure makes it a very popular plant among bees, butterflies, moths, flies, and hummingbirds alike. Unlike many other popular garden flowers, it blooms from late summer into autumn, making it extra valuable to pollinators as it provides them with ample energy as they prepare for winter.

Its central taproot with branching stolons allow obedient plant to spread with little helpful effort from the gardener. However, this means that it can spread aggressively if one is not careful, and may easily become invasive outside of its native range. If you’re not located in North America, place these plants in pots to help prevent them from spreading and becoming invasive. These roots, though, are good at taking up water and nutrients, making it somewhat useful in cleaning soil and water.

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Obedient Plant Fact Sheet:
PLANT TYPE
Herbaceous Perennial
HARDINESS ZONES
USDA 3 – 10
LIGHT REQUIREMENTS
Full sun to partial shade
BLOOM COLOR
Purple, pink, white
BLOOM PERIOD
August – November (Late summer to fall)
MAXIMUM GROWTH
Height up to 122 cm (48 in), spread up to 91 cm (36 in)
PLANTING DEPTH
Seeds: press gently into soil; Bare root/cutting: just enough to cover roots
WATER QUALITY
pH 5.5 – 6.5

Obedient Plant Growth, Hardiness & Climate

obedient plant flowers growing on the edge of a pond
Robin_ottawa from Ottawa, Canada / CC BY-SA

An easy and low-maintenance plant, obedient plant grows quite well with little effort. With ample moisture and sunlight, this plant can grow up to four feet tall and spread up to three feet via stolons in a matter of a couple of months. Hardy plants, they can tolerate some frost and can bloom from August through November, so long as the soil doesn’t freeze.

Obedient plant is considered a bog plant, though it can be found in woodlands and prairies with moist, well-draining soil. As a bog plant, it prefers soils that are slightly acidic, typically ranging from 5.5 to 6.5. Full sun works best for them, but they can tolerate partial shade, particularly if being grown in a hot region.

Zones 3 through 10 work well for this plant as it’s found in the central and eastern regions of Canada and as far south as Texas, but the hotter the area, the more water it will require. Obedient plants are quite hardy, able to tolerate drought as well as flooding, but prefer soils that are moist (not saturated).


How to Plant Obedient Plant in Ponds

how to plant obedient plant
Salicyna / CC BY-SA

If growing from seeds in the spring, all you need do is gently press the seeds into damp soil and keep the soil moist. Within a few weeks, germination should occur. If planting from a cutting or a bare root plant, bury them in just enough soil to cover the roots. Do this along the banks of your pond, where the soil is moist but not saturated. Obedient plant can withstand standing water up to two inches up its stem, but does not prefer these conditions for prolonged periods of time.

When planting from seed, the easiest way to do this is to sow the seeds in early winter before snow falls. Snow and ice that forms over the soil in the winter, in combination with the soil shifting as it freezes and thaws, will work to stratify the seeds, or essentially scratch them. This helps the seeds to sprout more easily once spring arrives.

Since each plant can spread up to three feet via stolons and give rise to new plants from these roots, you may consider planting obedient plant in pots to help mitigate its spread. This is particularly important if you live outside of its native range. Make sure these containers have holes in the bottom to allow for proper drainage.

You may also slow their spread by planting them in soils that are slightly poorer and drier, rather than the moist high quality soil. As hardy plants, they should still grow just fine but not as aggressively.


How to Care For Obedient Plant

ruby throated hummingbird at purple obedient plant flowers
A female ruby-throated hummingbird sips nectar from an obedient plant.                                                                  US Fish & Wildlife Service Midwest Region / CC BY-SA 2.0

Obedient plant doesn’t require much care – so long as they have access to water and sunlight, they grow quite easily. The downside of this, though, is that they can spread aggressively if you’re not careful. Plant them in pots to prevent this spread, or divide plants every year or two. You can plant these cuttings, or dispose of them appropriately (in a trash bin or compost heap, as long as they can’t escape into natural ecosystems).

As implied by their name, obedient plants are, well…obedient. You can move the flowers gently about their stalk axis, and the flowers will stay put in that position for some time. You may need to move them into the desired position a few times to get them to stay that way permanently.

This plant is also a prolific seeder, which further contributes to their ability to spread quickly and effortlessly. To prevent this, you’ll need to be vigilant about cutting off the flowers before they have a chance to go to seed. Doing this also increases the chances of getting a second round of blooms, which is a bit of a double-edged sword – you’ll enjoy the beautiful flowers longer, but you’ll also need to check and snip these flowers, too.

Any old foliage that is left as the year ends, leave on the plants to act as a sort of insulating natural mulch layer for the plants. Snip off this dead foliage in the spring to help kick-start their exit from dormancy. As always, make sure to clean any foliage from your pond to maintain healthy water quality.


How to Winter Obedient Plant

No specific action is necessary to take to help obedient plant survive winter. Just let it die down to its basal leaves, or the leaves that are arranged in a whorl just atop the soil. The plant will come up again the following spring just fine. If you’d like to enjoy blooms year-round, you may bring them indoors for the winter and continue snipping flowers to encourage repeated blooming.


Is Obedient Plant Toxic, Poisonous or Invasive?

Obedient plant is only considered native to the US and Canada. Outside of this range, it can be considered invasive. Even if it’s not listed as invasive but you live, for example, in Australia outside of its native range, you should take care to plant it in containers and snip flowers before the plant forms seeds to control its spread.

If you live in the UK and seek to have obedient plant, consider that obedient plant is technically invasive there. As mentioned previously, a remarkably similar plant group are the dragonheads (Dracocephalum), also known as snapdragons, which are native to Europe and Asia, and also found in the mint family. They look much the same, and also attract bees, butterflies, and hummingbirds alike while inhabiting similar moist, well-draining habitats as the false dragonheads found in North America.

While not considered toxic to humans or animals, obedient plant does have a rather unique adaptation – it contains not only external, but also internal idioblasts. Idioblasts are specialized sac-like cells that typically exist externally on leaves to hold oils, resin, tannins, or anything else the plant has evolved to use to protect itself from predators. They tend to be expensive for plants to make, so it’s somewhat uncommon to find not only the more typical external foliar idioblasts, but ones existing inside of tissues as well.

Obedient plant, however, is one of only two known species in the Lamiaceae family that also has internal idioblasts, which hold highly concentrated oils. Since obedient plant doesn’t seem to suffer from being browsed on by deer, rabbits, or even insects, botanists believe these internal idioblasts exist as an extra protective barrier against being eaten.


Is Obedient Plant Edible? Will Fish Eat it?

Obedient plant is technically edible, but pond fish are unlikely to eat it due to the oil-rich idioblasts that exist on its leaves and in its stems and roots. These produce a flavour that is evidently unpalatable, as evidenced by wildlife and insects tending to avoid this plant.


Where to Buy Obedient Plant & Seeds? (UK & US)

Obedient plant is readily available from online outlets, as well as select home improvement/garden supply stores, and nurseries. It’s most easily purchased online if you live outside of North America.

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