Propagation
Helleborus can be propagated by division or seed. The division of a plant gives identical plants and reliable flowering. Growing from seed:
The best time for growing hellebores from seed is early summer. It is important to sow the seed as quickly as possible after harvesting. As seed dries it reduces germination. The soil must remain moist over the summer. The seeds will germinate the following spring. As the primary leaf emerges the seeds need to be transplanted. The base of the seedling is weak – it should not be touched – only handle the leaves. The full development of a seedling to a flowered plant takes three years for all hellebores species. Growing from divided liners (tissue culture):
Philosophy: The most important factor in producing good retail quality flowering helleborus is to plant your liners in the finished containers early enough to take advantage of variable spring weather. Helleborus thrive in the cool, variable weather. If the liners are planted in the early spring they will enjoy a strong growth curve. When the warmer summer weather arrives the growth slows down significantly. As the cool fall weather arrives the plants enjoy another growth explosion that allows the foliage canopy to double in size. Plants flower 100% the first year.
Planting: Plant liners deep but do not bury the crown. This increases branching, which results in more flower stems. Depending on where you are located you can plant outdoors when the spring night temperatures can be trusted to stay near 30-35F. Plants can take a frost but pots should not be allowed to freeze solid.
Root Media: Recommend media with high coarse peat percentage.
Root Media Moisture: Plants should not be allowed to wilt; keep roots moist but not wet. A good grower will observe the roots often. The roots are thick and often brown. A healthy plant will always have white tips on the roots.
Fertilizer: A well-balanced fertilizer in NPK is beneficial for root development and height control, one higher in Nitrogen is recommended during the growing season because the end result will be a higher concentration of flower shoots and larger flower diameter during forcing. Check roots often in hot weather. Plants will not be very active during very hot weather. As this happens, decrease fertilizer application frequency or discontinue altogether. Keep a close eye on EC levels at this time. Recommend checking levels weekly. Once brought inside the greenhouse for forcing, switch to a fertilizer with a higher concentration of Potassium than Nitrogen, for example a 0.5:1 /N:K₂0.
EC and pH: Fertilizer solution should be 1.0-1.8 mS/cm during growing season and once indoors, forcing cultivation requires 1.0 mS/cm. Remember to include the EC level of your clear water. Routine pH and EC screenings are recommended to keep levels in check. The proper pH target should be 5.5-6.0
Heat and Light: Plants benefit from shade in warm climates. Growing on bare soil helps for climates with hot summers. Try to keep roots as cool as possible
Pinching: Not required.
Pest and Disease Comments: Thrips are common on Helleborus. Aphids enjoy Helleborus as well. Be wary of these pests in the fall. Routine fungicide drenches are recommended for a broad spectrum of root diseases during hot weather.
Finishing: As fall temperatures decline the plants will put on new growth before flowering. The plants enjoy the cold weather and set bud easily. They can take sub-freezing temperatures. If grown outdoors all winter and temperatures go below 25-degrees consistently the plants should be covered. The grower can bring the plants into a “frost-free” cold greenhouse and generate flowering based on genetic characteristics.
Helleborus can be propagated by division or seed. The division of a plant gives identical plants and reliable flowering. Growing from seed:
The best time for growing hellebores from seed is early summer. It is important to sow the seed as quickly as possible after harvesting. As seed dries it reduces germination. The soil must remain moist over the summer. The seeds will germinate the following spring. As the primary leaf emerges the seeds need to be transplanted. The base of the seedling is weak – it should not be touched – only handle the leaves. The full development of a seedling to a flowered plant takes three years for all hellebores species. Growing from divided liners (tissue culture):
Philosophy: The most important factor in producing good retail quality flowering helleborus is to plant your liners in the finished containers early enough to take advantage of variable spring weather. Helleborus thrive in the cool, variable weather. If the liners are planted in the early spring they will enjoy a strong growth curve. When the warmer summer weather arrives the growth slows down significantly. As the cool fall weather arrives the plants enjoy another growth explosion that allows the foliage canopy to double in size. Plants flower 100% the first year.
Planting: Plant liners deep but do not bury the crown. This increases branching, which results in more flower stems. Depending on where you are located you can plant outdoors when the spring night temperatures can be trusted to stay near 30-35F. Plants can take a frost but pots should not be allowed to freeze solid.
Root Media: Recommend media with high coarse peat percentage.
Root Media Moisture: Plants should not be allowed to wilt; keep roots moist but not wet. A good grower will observe the roots often. The roots are thick and often brown. A healthy plant will always have white tips on the roots.
Fertilizer: A well-balanced fertilizer in NPK is beneficial for root development and height control, one higher in Nitrogen is recommended during the growing season because the end result will be a higher concentration of flower shoots and larger flower diameter during forcing. Check roots often in hot weather. Plants will not be very active during very hot weather. As this happens, decrease fertilizer application frequency or discontinue altogether. Keep a close eye on EC levels at this time. Recommend checking levels weekly. Once brought inside the greenhouse for forcing, switch to a fertilizer with a higher concentration of Potassium than Nitrogen, for example a 0.5:1 /N:K₂0.
EC and pH: Fertilizer solution should be 1.0-1.8 mS/cm during growing season and once indoors, forcing cultivation requires 1.0 mS/cm. Remember to include the EC level of your clear water. Routine pH and EC screenings are recommended to keep levels in check. The proper pH target should be 5.5-6.0
Heat and Light: Plants benefit from shade in warm climates. Growing on bare soil helps for climates with hot summers. Try to keep roots as cool as possible
Pinching: Not required.
Pest and Disease Comments: Thrips are common on Helleborus. Aphids enjoy Helleborus as well. Be wary of these pests in the fall. Routine fungicide drenches are recommended for a broad spectrum of root diseases during hot weather.
Finishing: As fall temperatures decline the plants will put on new growth before flowering. The plants enjoy the cold weather and set bud easily. They can take sub-freezing temperatures. If grown outdoors all winter and temperatures go below 25-degrees consistently the plants should be covered. The grower can bring the plants into a “frost-free” cold greenhouse and generate flowering based on genetic characteristics.
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