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.