Typically known as lunaria or silver dollar plants, these iridescent "leaves" are actually the seed pods from the plant known as Lunaria annua. Native to both Europe and Asia, lunaria is actually part of the Brassicaceae family, making them the plant relative of foods like broccoli and Brussels sprouts.
While their botanical name alludes to them being annuals, lunaria plants are actually classified as biennials. Lunaria is suited to USDA hardiness zones four through eight and is best planted in spring after the final frost—it will grow quickly, with seedlings emerging in just 10 to 14 days. However, because the plant is biannual, don't expect to see any flowers or seedpods until the following year.
|Botanical Name||Lunaria annua|
|Common Name||Lunaria, silver dollar plant, money plant, honesty, moonwort|
|Plant Type||Herbaceous perennial|
|Mature Size||2–3 ft. tall, 1–2 ft. wide|
|Sun Exposure||Full sun, partial shade|
|Soil Type||Moist, rich|
|Soil pH||Neutral to acidic|
|Flower Color||Purple, pink|
|Hardiness Zones||4–8 (USDA)|
|Native Area||Europe, Asia|
Lunaria plants have a long taproot and do not transplant well, so they're almost always grown from seed. Sow the seeds outdoors in spring as soon as you can work the ground, covering them lightly with soil and water. Many gardeners love to plant lunaria along woodland borders, where they won't have to fuss with them—they'll thrive and see on their own as long as the conditions are right.
These unique biennials are grown not for their leaves, but for the flowers that come in the spring of their second year and even more so for what their flowers produce: the seed pods that eventually become the namesake "silver dollars." The foliage in their first year consists of a basal rosette of leaves, and the flowers that eventually emerge in the spring of year two are typically purple.
The seed pods that follow the blooms are known as "silicles." They start out green in color, later shedding the shade along with their seeds. The fully dried seed pod that remains (which is actually just a see-through membrane) is an off-white color with a sheen that makes it shine like a coin. These "silver dollars" are papery to the touch and not perfectly round but rather oblong, with a short, needle-like projection that hangs down from the bottom of each seed pod.
The pods can be used in dried floral arrangements, wreaths, and more. In fact, you do not even have to be proficient at floral design to use them—simply insert a few dried bundles into a vase for a unique display, or hang them from a hook over a window so that the sun can shine through them.
Lunaria plants do well in both full sun and partial shade locations. In a hotter summer climate, a bit of afternoon shade is appreciated, but ultimately the plant should get around eight hours of sunlight daily in order to grow strong roots and eventually flower.
Grow your lunaria plants in a friable, deeply cultivated soil to accommodate their long taproots. Additionally, they prefer a soil mixture that is well-drained and humusy—it should stay evenly-moist without becoming waterlogged. soil that stays (or, through irrigation, can be kept) evenly moist.
Keep the soil your lunaria is housed in consistently moist throughout the growing season—about one inch of water (through rainfall or manual watering) a week should do. Keep in mind, the exact amount of water your plant needs can depend on your environment and its location in your landscape. Plants located in constant sunlight may be more thirsty than their shade-dwelling counterparts.
Temperature and Humidity
Lunaria plants need temperatures between 60 degrees Fahrenheit and 70 degrees Fahrenheit to germinate and become established in the landscape. After that, as long as they're planted in the proper USDA hardiness zone, they have no special temperature or humidity requirements.
Once a year in the spring, treat your lunaria plant to a feeding with an organic or slow-release fertilizer to help encourage ample blooming.
A potential drawback in growing silver dollar plants is the ease with which they spread. Check with your county extension office before planting any to determine whether they are listed as invasive plants in your region (in which case they have the capability to crowd out native vegetation). As invasive plants go, though, lunaria plants are hardly among the worst offenders.
Under the right growing conditions, one plant will eventually multiply into many plants, and it's their ability to re-seed that makes them such aggressive spreaders. However, if you're hoping to contain your lunaria collection, controlling the plant is straightforward enough. Harvest the plants after their seed pods are fully developed but before they can drop any seed. This practice kills two birds with one stone since you will want to harvest them anyway in order to use the attractive seed pods.
When you're ready to harvest, cut off the plant at its base and bring it indoors. Tie your bundle of lunaria with some twine or string and suspend it upside-down in a room that boasts low humidity levels. The seed pods should be fully dried in about two to three weeks—you'll notice that the husk (which is the green, outer layer) has likely fallen off by itself, but if it doesn't, you can gently rub it off. Caring for the pods consists essentially of harvesting and drying them properly—they require virtually no maintenance beyond that.
Common Pests and Diseases
While extremely easy to care for, lunaria can encounter a few disease issues that can be a nuisance. Beyond being susceptible to aphids (which can be treated using an insecticidal soap or horticultural oil like neem oil), lunaria plants can also come down with diseases like septoria leaf spot. Septoria leaf spot is a fungal disease that creates gray and black marks on the leaves of the plant. LIkewise, clubroot, another issue for lunaria, can cause the leaves to wilt or yellow. If you notice signs of either of these issues, remove any part of the infected plants and isolate it if possible until signs of infection pass.