Starting Lisianthus From Seed

When I first started growing cut flowers, I ordered lisianthus plugs (small plants) because the plants need to be started in January and February to have them flowering in August and September. I had read they were difficult to grow from seed but after a couple years I thought I'd give it a try since seeds were much more affordable and I knew I needed to start them really early.


It turns out that lisianthus are not difficult to start from seed under lights. The seedlings are tiny and grow very slowly but nothing complicated is involved. Because they grow so slowly, lisianthus plants are really expensive. They are also a terrific cut flower, so seed is the way to go if you want to save money and enjoy getting the garden season started indoors in January or February.


Lisianthus take about 6 months to flower from the time the seed is planted. Seed planted in early January will bloom in July and ones started in February will bloom in August. You may be able to plant them in March and have them bloom in September, but their development slows with colder weather, so January and February are safer.

Lisianthus with zinnias, statice and gomphrena

Lights for Seed Starting
I have another post here about how to start seeds under lights. I use plug trays (you can buy them at Johnny's) for lisianthus rather than liners because the seedlings are so tiny they don't need to be transplanted for at least a couple months.


Varieties
Lisianthus have been bred to be short 6-8” bedding types or taller 1-2 foot varieties for cutting. The taller varieties will often say they reach 3 feet or more but they don't get that tall in a single season here in zone 5.


Choose the variety of seed depending on whether you want them for bedding or cutting. I have only grown the tall varieties for cutting. Some to look for are:

• Cinderella – a double lisianthus that comes in blue, ivory, lime, pink and yellow. To me, the yellow is off-white rather than yellow like a sunflower. Blue is a medium purple blue. Lime is a slightly greenish white. The pink is a good medium pink that does not look red or coral.
  
• Twinkle – a single lisianthus but available in a deep blue/purple color that is not available in any other lisianthus.
  
• Echo – Echo is an older variety that comes in a wide selection of colors and many picotee types. Picotees are white with color on the last ¼ inch of the petal.
  

Pelleted Seed
Because lisianthus seed is fine as dust, you want to be sure the seed is pelleted. The packet or catalog description will say it is pelleted if it is. Pelleted seed comes in plastic vial inside the seed packet. Each tiny seed has been placed in a pellet about the size of the head of a pin. The pellet dissolves on contact with water, so be sure your hands are dry when you touch them.

Pelleted lisianthus seed

Obtaining Seed
Lisianthus seed is available from many mail order companies including Johnny's, Pinetree Garden Seeds and many others. You can probably also find it at any good seed supplier like Downtown Home and Garden.


Sowing the seed
I have always grown lisianthus the same way. I am sure other ways work but this is the one I know and trust.


Materials

• A good soil-less seed starting mix.
  
• A plug flat or a 72 cell per flat liner.
  
• A flat or other container to hold water
  
• A flat to hold the liner trays or plug flat
  
• A clear plastic humidity dome. These domes fit over a full flat.
  
• Spray bottle
  

1. Fill the number of plug or liner cells you need.
   
2. Put about an inch of water in the water tray and set the soil containers in the water. After a few hours they will absorb the water so the grow mix on the surface is moist. Remove the containers from the water and let them drain in the sink for a few minutes.
   
3. Sow the seed on the surface of the grow mix. Do not cover the seeds - they need light to germinate. Because the seed is pelleted, you can sow one seed per cell.
   
4. After sowing the seed, spray the pellets and soil surface with water. Part or all of the pellet may dissolve but don't worry if part of the pellet is still there.
   
5. Put the seed containers in their flat, cover the flat with the humidity dome and place under the lights. The lights should be just over the humidity done but not touching it.
   

Get in the habit of checking on the flat every day. The seeds will sprout in about 10 days. The seedlings are very, very small, about the size of the head of a pin at the most. You may need to re-moisten the surface of the soil mix from time to time with the spray bottle. It is fine to spray the seedlings. Sometimes part of the undissolved pellet will be on one of the first leaves and spraying will dissolve it.


About a 4 weeks after you start the seedlings they might be as large as 1/4 inch across. Prop up the corner of the humidity dome for a day to give the seedlings a chance to adapt to drier air and then remove it. After removing the humidity dome, check the moisture in the soil mix every day. If only one or two cells are drying out, you can moisten them with the spray bottle. If most of the cells are drying out, you can bottom water all of them by placing the plug flats or liners in an inch of water.

Lisiathus in a 200 plug tray

Algae or moss may grow on the soil mix surface. It won't harm anything but you can rub it away after the seedlings are up if you want.


Transplanting to Larger Containers
Although they grow slowly, if started in plugs your lisianthus will need to be bumped up into small pots or larger liners eventually. When the roots are showing through the bottom of the plug, check to see if it is time to transplant . You can use the end of a pencil to push on the plug from the bottom. If the roots are reaching the outside of the plug, it is time to transplant. If started in liners you will be able to wait quite a while before transplanting.


Hardening Off
Lisianthus can tolerate cold weather. They are perennial in zones 7 or 8 and can survive winters hereif grown in a hoophouse and protected.
Before going from under the lights to their final locations in the garden, your lisianthus should be hardened off, This can be done as soon as there is mild daytime weather. If you have a cold frame you can put them in it when the nights will not be freezing and they will be fine. Once they have acclimated to cooler weather, they can tolerate frosts easily if protected by a cold frame. If you don't have a cold frame, move the plants in and out of the house during the day to get them used to bright sunlight and winds, but bring them inside at night if frost threatens.


Planting Outside

I am always paranoid about planting lisianthus outside too early because they take so long to grow that I don't want to risk losing them. If you are planting them in your yard, you can cover them up if it is going to get really cold. In that case it is probably fine to plant them outside in early May. If you can't cover them up in an emergency, mid-May is perhaps safer.