Pot plant production of Lachenalia

 

Lachenalia are related to spring flowering bulbs like hyacinths and tulips. Lachenalia are however different and should not be treated like these bulbs. These differences need to be taken into account when Lachenalia is compared to other spring flowering bulbs.

Lachenalia is indigenous to South Africa and is adapted to a climate of large temperature differences between night and day as well as very high light intensities. It is a winter growing bulb under South African conditions.

Temperature during storage and during the growth season has an important impact on the growth of the plants. Ideal growth temperatures are: average of 13-17⁰C for the first 4 weeks after planting, then a decrease in temperature of 10-13⁰C for the next 4 to 6 weeks and an increase again until flowering starts.

We can advise on specific temperature treatments (storage and planting) if specific information on temperature,
light intensity and market periods are supplied. 

All Lachenalia cultivars are protected by plant breeder's rights. Production of bulbs takes place under license in South Africa. Correct bulbs (minimum size 6-7cm) for pot plant production will be supplied.

A new crop

Lachenalia is still a new crop in the international market. We do not know everything about the crop yet, and there are some challenges related to Lachenalia production. Currently general guidelines can be provided for pot production.

Uneven flowering of bulbs in one pot

Bulbs are normally planted three per 12cm pot, however uneven flowering between these bulbs is still problematic for growers. We are conducting research to overcome this situation. In the mean time we advise that bulbs be planted one bulb per pot (9-10cm) and repotted to larger pots when elongation of inflorescence commence. Plants in a similar stage of development can thus be potted together. Depending on the specific growth environment unevenness can be less. Under South African conditions flowering is more even than under Dutch conditions. Research to determine the causes of uneven flowering and find a solution is under way.

Scheduling

There is two aspects that need to be taken into account when scheduling is addressed. Firstly there are late and early flowering cultivars. Scheduling is thus needed to get all colors (cultivars) to flower together.

Secondly the growth conditions have a major influence on flowering time and this need to be addressed by each individual grower for his specific growing conditions. The technology exists to get flowering pot plants year round. Each grower needs to adapt production schedules for each cultivar under his/her greenhouse conditions.  We will assist if you supply specific information on the micro-environment/glasshouse, where pot plant production will take place.

Note: Lachenalia in nature occur in semi-arid areas. Any moisture during storage in the last six to eight weeks before planting will lead to immediate root growth. Roots can reach two centimeters overnight. It is thus important to ensure that bulbs are stored dry until planting.

Factors influencing pot plant production

TEMPERATURE

• Storage temperatures – All storage temperatures are given under dry bulb conditions.

Shifting of flowering time:

Storage temperatures are used to facilitate scheduling. Low temperature storage just after harvest is used to produce flowering plants year-round. This scheduling will be done by the bulb supplier provided that the correct information on the time of pot plant marketing is available.

Flower development:

Bulbs need a minimum of 18 weeks at 21-25⁰C for flower development. Dry bulbs will be shipped during the latter part of this period.

Pre-plant temperatures:

A three week treatment at 9⁰C (dry) just before planting shortens the growth period by 3-5 weeks (Table 2). This can thus be used to schedule late and early cultivars to flower together.

• Growth temperatures – Ideal growth temperatures are: average of 13-17⁰C for the first 4 weeks after planting, then a decrease in average temperature of 10-13⁰C for the next 4 to 6 weeks and an increase (to ±17⁰C) again until flowering starts.

Growth cycle of Lachenalia under South African conditions

1-4 weeks	5-1- weeks	11-15 weeks
Warmer autumn	Cool winter	Warmer late winter, spring

Maximum temperatures of above 30⁰C (at any stage) lead to large scale bulb rotting and flower abortion. In general higher average temperatures led to more vigorous vegetative growth. Lower average growth temperatures result in more compact growth.

Minimum temperatures of 0⁰C and below should be avoided. Long periods at these temperatures lead to leaf and flower damage.

• Marketing temperatures – 10-15⁰C – better shelf life.

LIGHT INTENSITY

Lachenalia can be grown under various light intensities, provided that correct treatments are given. High light intensities lead to natural shorter growth and low light intensities lead to long leggy growth. Under low light intensity growth retardants well have to be applied to keep plants short.

Temperature and light intensity need to be addressed together – e.g.

Table 1: Effect of light intensity together with growth temperatures on plant growth.
             * Conditions are not preferably because it will result in losses due to rotting and flower abortion

Pot Plant Production

Potting medium: Good quality potting medium (good drainage essential).

Fertilization: Slow release fertilizer for flowering plants.

Pot size: three bulbs per 12,5/13cm pot.

Water: Keep moist (not wet) at all times.

Bulb size: 6-7 cm circumference and larger (smaller bulbs do flower, but give low number of flowers and poor quality). Use larger bulbs (bigger than 8cm) when growth temperatures during the first 4 to 6 weeks are low (average below 13⁰C). Smaller bulbs (6-8cm) can be used when planting temperatures are higher (average 15-17⁰C).

Cultivars:

Early – Romaud*, Romelia, Ronina, Namakwa

Late – Robyn, Rosabeth, Rolina, Rupert, Fransie

* Cultivars in bold are better suited for pot plant production

Planting

Table 2: Effect of cold pre-plant storage temperatures on growth period under South African conditions (autumn planting – average temperature above 13 during first four weeks).

A number of trials are currently being conducted at ARC-Roodeplaat on temperature treatments before and after planting. The information will be updated as data become available.

If you supply growth temperature and light intensity regimes we can give advice on how to produce pot plants for specific periods.