Growing Lisianthus in the Pacific Northwest: From Plug to Summer Bloom

Growing lisianthus in the Pacific Northwest can feel a bit mysterious, especially for local gardeners and newer flower farmers in the Seattle–Tacoma area. These ruffly, long-lasting summer flowers aren’t commonly found in local nurseries, and much of the growing advice available isn’t written with Western Washington’s cool springs and mild summers in mind.

This post focuses specifically on growing lisianthus from plugs to flowers in the Pacific Northwest. Whether you’re planting lisianthus in a backyard cutting garden or adding them to a small flower farm, these tips are based on what has worked for me growing lisianthus in Edgewood, Washington.

I started growing lisianthus more than 25 years ago on the patio of my first apartment. Today, I grow lisianthus plugs for local gardeners and flower farmers at my small nursery and flower farm in Edgewood, Washington, plants that have proven to be worth the patience when grown with our local climate in mind.

Plant Lisianthus Plugs Soon After Arrival

In the Pacific Northwest, lisianthus plugs are best planted in early spring. Lisianthus benefit from a long, cool establishment period, allowing roots to develop before warmer temperatures and longer days arrive.

Plant lisianthus soon after you receive them. If watering is needed prior to planting, set the plugs in a tray or cookie sheet, pour water into the tray, and allow them to soak it up from the bottom.

Cold tolerance note: Don’t worry too much about cool temperatures after planting. In my experience, lisianthus can withstand hours in the upper twenties with no issues. If plugs are newly planted, I may mulch lightly or use frost cloth, though I don’t really find it necessary. One spring, a greenhouse circuit breaker tripped during 20-degree weather and my lisianthus plugs froze solid, yet they recovered just fine.

Prepare a Well-Amended, Well-Draining Bed

Lisianthus grow best in rich, well-draining soil. Amend your bed with quality compost and fertilizer before planting.

If you follow no-till growing practices, apply a 1–2 inch top dressing of compost with organic fertilizer mixed in.

Handle Roots Gently

Do not tease out the roots when planting. Lisianthus are tough little plants, but they prefer minimal root disturbance.

Plant Slightly Above Soil Level

To reduce the risk of crown rot, especially during our wet Pacific Northwest springs, plant lisianthus slightly above ground level in well-draining soil.

Space Plants for Airflow

Space plants approximately 4 inches apart to allow for good air circulation and healthy growth.

Optional Root Protection

Some growers dip lisianthus plugs in Rootshield at planting to help reduce fusarium root rot. While this practice is suggested by some plug suppliers and farmers, many growers who start lisianthus from seed report seeing no significant difference in field success rates.

Fertilize Regularly

Lisianthus require regular feedings. I apply a quality organic fertilizer high in nitrogen early on, switching to one higher in phosphorus as stems begin to elongate.

I also fertilize weekly with a calcium nitrate fertilizer. Here is a homemade option I use:

Korean Natural Farming Water Soluble Calcium Fertilizer:

• Finely crush 12 or more eggshells and cook them in a pan until browned. (Use ventilation—it will smell.)

• Place the cooked shells in a quart jar and fill with apple cider vinegar, leaving a little headspace.

• Cover with cheesecloth. The mixture will bubble vigorously.

• Let sit for 1–2 weeks, then strain out the shells and seal with a lid.

• This mixture is shelf stable for months. I use 1.5 teaspoons per gallon of water.

Be Patient

Lisianthus are very slow growing. It may look like little is happening above ground, but the plants are quietly building a strong root system. Patience is an important part of growing these flowers.

Harvesting Lisianthus

The first bloom typically opens one to two weeks before the rest. Many growers harvest this initial flower for short-stem bouquets before cutting the full stem.

For longer stems, harvest when two to three additional blooms have opened. Condition lisianthus as you would other cut flowers.

Lisianthus reward patience with long-lasting blooms and soft, elegant beauty in the summer garden. For local gardeners and flower farmers in the Seattle–Tacoma area, growing lisianthus from plugs makes it possible to enjoy these blooms without starting from seed. Growing them locally means learning their rhythm, and enjoying flowers that last beautifully in the vase.

The Art of Growing Lisianthus: From Seed to Plug

I first grew lisianthus more than 25 years ago on the patio of my first apartment, just after my husband and I moved in together. When we relocated to the Seattle–Tacoma area over twenty years ago, I mostly forgot about them—partly because I never saw them available here, and partly because it’s easy to get distracted by so many other beautiful plants that do grow here. Today, lisianthus are once again part of my life at my small nursery and flower farm in Edgewood, WA.

One summer in July, while visiting friends in Idaho, I rediscovered lisianthus. We came across a nursery just south of the Canadian border that was giving away all of its annual plants—literally hundreds. Among them were lisianthus, which brought back that early memory of growing them. Of course, I grabbed a few for myself and a friend. That moment rekindled my inspiration to grow lisianthus again—this time from seed. Up until then, I’d only ever seen a few lisianthus plants available at a nursery on the Olympic Peninsula. It felt like the right time to try, and it’s been a fun learning journey ever since.

I should pause here to say that I’ve become very mindful about moving plants long distances. With the rise of invasive species, it’s important to use good inspection practices before bringing home plants—or even anything from nature that you’ve found elsewhere. My family doesn’t even bring pinecones back from road trips anymore, hard as that is. Lisianthus are fortunately easy to inspect because their leaves and stems are smooth, but I also recommend pulling plants from their pots to check the root ball.

Growing lisianthus isn’t for the faint of heart. It takes patience, some failure, and learning how they respond in your particular growing environment. But with dedication, you can be rewarded with one of the most elegant flowers you’ll ever grow. Here I’ll focus on starting them from seed and producing strong lisianthus plugs.

Lisianthus seeds are very tiny, usually sold in pelleted form for easier handling. I’ve only grown the pelleted type. These can be tricky because if they dry out before the seedlings fully emerge, the coating can prevent perfectly good seeds from breaking through. Keeping them consistently moist is essential throughout most of the growing process.

Before sowing, think about your growing medium and method. You can buy seedling mixes or make your own. While soil choice matters, I’ve found that success with lisianthus has a lot more to do with growing conditions than the mix itself. I prefer a very fine-textured medium. I sift mine through quarter-inch hardware cloth and use a blend of fine professional propagation mix, a quarter of it made with quality compost, and trace elements. Every grower has their favorite recipe, so experiment until you find what works best for you.

I’ve tried growing in plastic 6-packs, mini soil blocks, and Winstrip trays. My preference is Winstrip trays because of their root-pruning qualities. Soil blocks are great for many crops, but in my greenhouse they dry out too quickly, and lisianthus seedlings don’t forgive a missed watering. Disposable plastic trays do hold moisture but I’ve moved away from using them for sustainability reasons. In my conditions, Winstrip trays strike the right balance. In my experience, the root pruning qualities of soil blocks and Winstrup trays do yield a higher percentage of quality plugs.

Lisianthus grow slowly, and timing varies with variety, temperature, fertilizer, and light. I sow in Early to mid-November in my Seattle-area greenhouse, starting on heat mats set to 70°F. I like to add a little seaweed extract to my medium at sowing time to help keep the soil moist. Germination usually takes 7–10 days, but the seedlings are nearly invisible at first—you’ll need patience and trust. Moisture is critical during the first month, both to dissolve the pellet coating and because the seedlings are putting all their energy into one long root. Any slight dry spell at this stage can compromise their future quality. I suggest using a very fine mist sprayer daily at this stage if your growing conditions are on the dryer side.

I’ve found little difference between starting in 72-cell or 128-cell trays. The 72s are easier to pop seedlings out of with your finger, but the 128s save space and encourage slightly more branching in the roots when grown side-by-side with 72’s. Either size produces strong plants as long as growing conditions are right. For home gardeners, 10-14 weeks from sowing to transplant-ready is a good benchmark. My greenhouse dips to 50°F at night during the coldest months, with daytime highs easily reaching into the 70s in November. In winter, my daytime temps are in the mid to upper 60s. I prefer not to start lisianthus until the air temperature cooler than the heat mats, which I keep at 70–72°F. I’ll note that I once had lisianthus survive a freeze down to 22°F at six weeks old—they’re tougher than they look.

Fertilizer is another key factor in growing lisianthus. Calcium is especially important. I begin feeding within a week of removing trays from the heat mat, using a high-quality fertilizer weekly along with calcium. I don’t dilute differently for younger seedlings—it’s more about keeping them evenly moist before feeding so you don’t have to water much that first feed. I made my own calcium fertilizer from egg shells which you can find on my website.

Lisianthus growers often say, “hurry up and wait”—and it’s true. For the first 4–6 weeks after germination, seedlings appear frozen in time. They’re not; they’re busy developing roots you can’t see. By week six or seven, healthy plants usually begin putting on noticeable leaf growth. I’ve found Voyage, Corelli, ABC, and Roseanne varieties to leaf out a little faster (if “fast” can be said of lisianthus), though timing does vary slightly by color. Arena varieties are more challenging in my experience, often two weeks slower than the others I’ve grown.

During this leaf growing stage, watering can be reduced. Lisianthus prefer drying out more between waterings at this point, reflecting their origins in the prairies of the southern U.S. and similar climates near the equator. Once plants reach about four sets of leaves, it’s time to pot them up or transplant. This stage usually comes 4–6 weeks after the “hurry up and wait” stage—just when you’ve convinced yourself those tiny green specks you can finally see with the naked eye are actually going to survive.

Growing lisianthus is a long journey, but one that pays off in elegant blooms unlike anything else. What began as a rediscovery years ago has now become part of my yearly rhythm, from sowing tiny seeds in November to watching strong young plants take hold in spring. Here in Edgewood, WA, I grow lisianthus plugs for local gardeners and farmers who want to enjoy their beauty without the long wait from seed. For me, it’s both a labor of patience and a way to share these remarkable flowers more widely in the Seattle–Tacoma area that I call home.