For the climate here in the UK Lisianthus is a challenging crop to say the least. They are slow growing, they like the heat and dry ish conditions ( They originated from the prairies of America ) ......... so why bother when they are more high maintenance than even Victoria Beckham.
You only have to take on look at the stunning blooms to know why, and us flower farmers LOVE the challenge and satisfaction. They are also great alternative to roses - without the thorns YAY! and ranunculus. They come in shades of blues and purples which are not common in roses and ranunculus and better still they last 2-3 weeks in the vase - far longer than most flowers!
You may read how easy they are to grow, especially from far flung places around the world but their precipitation may not be as high as ours and they may be closer to the equator. That said it is very possible to grow fairly good crops here in the UK so it definitely worth persevering, especially if you are a relatively experienced flower farmer or home grower. Even if you are in your first few seasons it worth a go as they may just take you by surprise how rewarding they can be.
Plug plants are ideal and most flower farmers prefer to use plugs, however, they are very hard to get hold of here in the UK so sowing from seed is the only option. It's also worth noting at this point that a greenhouse/polytunnel and propagation equipment will be needed as they need such a long growing season and need to be protected from excessive rain. The flowers will hold water - especially the ruffled types and are prone to spotting and rotting when grown outdoors.
Sow Lisianthus seeds early
Lisianthus are VERY slow growing so need to be started in the Autumn - they are actually a short lived perennial but its best to grow them here as a Hardy Annual. They are incredibly tolerant of frost and infact need a period of cool weather initially to grow a strong root system. Only later in their growth stage when they come to bloom that they need heat.
Lisianthus seed is teeny weeny which is why it takes them so long to grow in the first 12 weeks but are usually supplied coated to make them easier to handle. They can take around 8 months top reach flowering stage. So seeds sowed in November will bloom in mid summer around July time
Fill trays or small pots with moist seed compost ( do not be tempted to use general purpose compost as they will need a PH neutral mix with the right balance of nutrients)
Sow the seeds onto the surface of the soil. No need to cover as they need light to germinate. Just press the seeds gently into the soil to make contact.
Cover with a propagation lid to keep them moist and place trays under grow lights. They will need 16 hours of light per day, with an ideal temp between 20-25°C. Maintaining this constant temperature with a thermostatically controlled propagator.
Germination takes around 2-3 weeks and once they gave sprouted remove the lid but keep them under the lights. Overwatering will leads to fungal diseases so allow the surface to dry out a little between waterings. Watering from below is ideal.
Feed them weekly with a general purpose fertilizer at half strength.
At eight to twelve weeks they will have formed 4 leaves and will be ready to transplant - transplant seedlings into their own trays with a general purpose compost.
At around the five months stage plants should have developed a tiny rosette of leaves and will be ready to plant into final positions in the greenhouse border. Do not be tempted to leave them in pots even though they are small. Harden then off gradually before transplanting.
Spacing & Location
lisianthus don't need much space. They can be planted very close together, 6-7cm is fine and you can also experiment with putting 2 plants per hole. They will however need to be planted in a sunny location. They will need a minimum of 6-8 hours of sunshine per day. They will also need staking or netting to ensure that they don’t fall over. Plants can get very tall, and the last thing you need when you have spent all of that effort on getting good plants  is for it to be ruined.
Weed Management
Because lisianthus stay small for so long aggressive weeds will quickly overtake plants and smother them. It may be worth planting them through a weed membrane with holes in, otherwise regular weeding every 2 weeks is necessary.
Feeding Lisianthus
Prepare the planting bed with plenty of compost, leaf mould and well-rotted manure, some fish bone meal will also be beneficial. After planting, they can be sprayed weekly with a liquid seaweed through the early months up until bud formation.
Checking the soil PH is crucial for a good lisianthus crop. They like a PH of between 6.5 and 7.0. Soil which is too acidic or alkaline will cause the foliage to yellow, plants will have less vigour, and fewer blooms.
Watering Lisianthus
During the early stages lisianthis should not be allowed to dry out, they need to be kept most for gemination to occur and in their first few months. As they grow and buds start to form they will need less and less watering as their roots will have grown down into the soil and this will mimic their natural prairie habitat when the weather gets hotter.
Flowers do not like getting wet and are prone to spotting and/or moulding if you water overhead with a sprinkler or hose so keep water at the base only and set up drip irrigation if you can.
Blooming & Second Flush
Regular feeding and watering along with adequate light are necessary for abundant blooms. If you have managed to sow in Autumn and can get seedlings into the ground in early April, in a hot summer you should get blooms in July and in turn may be able to get second flush off of your lisianthus in mid-September. However for this to happen the stars really do need to align AND we need a baking hot summer. If your plants don't bloom until August then there won't be enough time for a second flush. Hey most of us would just be happy with one flush quite frankly here in the UK!
To enable this make sure you are cutting the plants back almost to the base in their first flush. This will encourage long stems to shoot. Afterwards give them plenty of water again and a good feed to encourage then to grow once again.
Have you have succes or failiures with Lisianthus? Let us know, share your experiences with us in the comments.
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