The temperate species can be divided into 3 groups, each with similar growth requirements. Chart 2.
Chart 2 Temperate Pinguicula
P. corsica P. grandiflora P. longifolia P. vulgaris
Winter temperatures: 32-34°F (0-1 °C) Summer temperatures: 46-68°F (8-20°C) Growing period: 4-6 months. Dormant period: 6-8 months. Group 2
P. longifolia ssp. reichenhachiana P. macroceras ssp. nortensis P. ramosa P. vallisneriifolia
Summer temperatures: 59-84°F (15-29°C). Growing period: 7-9 months. Dormant period: 3-5 months. Group 3 P. algida P. alpina P. balcanica P. leptoceras P. macroceras P. nevadensis P. variegata P. villosa
Winter temperatures: 26-34°F (-3-1 °C). Summer temperatures: 45-65°F (7-18°C). Growing season: 3-4 months. Dormant season: 8-9 months.
The temperate Pinguicula are divided into 3 groups, those that grow in acid soil, basic soil, or in either. Their soil preference is indicated on Chart 1.
Acid growing media: Sphagnum peat moss; sphagnum (living or dried); 1 part sphagnum peat moss to 1 part perlite to 1 part sand (silica); 1 part sphagnum peat moss to 1 part perlite or silica sand; 1 part chopped sphagnum to 1 part sphagnum peat moss.
Basic or alkaline growing media: Equal parts of sphagnum peat moss, perlite or vermiculite and ground dolomite or limestone (some growers prefer to use less limestone). Various recipes call for a minimum of 1 tablespoon (15 ml) per quart (liter), of growing medium up to V2 of the medium mixture; 1 part perlite to 1 part vermiculite; or 100 percent perlite.
The temperature range required by each group is given in Chart 2. Generally, during the growing season it is best to maintain the temperature around the middle of the range. Night-time temperatures should be several degrees lower than the day temperature. It is vital that a constant temperature be maintained during dormancy, as changing the temperature results in the death of winter buds. In warm parts of the world refrigeration is required during active growth for some of the temperate species of Pinguicula.
The greatest loss of plants in temperate Pinguicula occurs while they are in dormancy. To reduce and/or eliminate loss, winter buds should be sprayed or soaked (about 15 minutes) in a full strength solution of a fungicide suchasBenlate. (Photo 5-6). The treated buds should then be loosely wrapped in damp living sphagnum moss and placed in sealed plastic bags for storage.
Group 2 plants can be stored in a refrigerator (not freezer), preferably near or on the bottom shelf where it is cooler. If the winter temperatures in your area are in the 34-39°F (1-4°C) range, plants can be stored outside. If the outside temperature varies very much from these values, other ways for maintaining low temperatures should be utilized.
Some of the species in the temperate group spend more time in dormancy than in active growth and require low temperatures during active growth. To provide dormancy for those Pinguicula species requiring freezing or near freezing temperatures
(group 1 and 3) we use two methods.
The first method involves growing the plants in our cool greenhouse; the winter buds are planted in late February or early March. The plants will grow and flower before the heat of late spring and early summer. After flowering, the plants start going dormant. The progress of dormancy in both flowering and non-flowering plants can be ascertained by checking for development of the winter bud in the crown area. When the winter bud starts to form we remove the plants from the greenhouse benches and place them on the floor in the coolest part of the greenhouse until winter bud formation is complete.
Attempting to keep the plants growing after winter bud formation has started is to court disaster. Once the winter buds have formed treat them with a fungicide as outlined previously and place them in sealed plastic bags. We put the plastic bags in the meat storage tray of our refrigerator until the next growing season.
The second method of providing proper conditions for species requiring freezing temperatures during dormancy is simplified by our new refrigerator. It has a meat tray, the temperature of which can be adjusted to be at or below the freezing point by controlling the opening to a portal which connects the meat tray area to the freezer. Once the portal is adjusted for the correct temperature, the winter buds, which are in moss in a sealed plastic bag, are placed in a styrofoam box or a small thermos bottle and then kept in the meat tray. The reason for putting the buds in the plastic box or thermos bottle is to keep the temperature of the buds constant when the meat tray is opened and items are removed or warm ones added. The styrofoam box should not be sealed too tightly and the thermos too should not be completely tightened because the buds are alive and need oxygen for cellular respiration.
Water & Humidity
This group of plants is particularly sensitive to humidity which should be high, over 75%, for best growth. Medium should be wet during the growing season and much drier during dormancy.
As a group, temperate Pinguicula grow best in indirect or shaded sunlight. In their native habitat they are usually shaded by taller growing plants. If using artificial illumination, start with about 900 foot candles and a 14-18 hour photoperiod during active growth. While dormant they do not need any light.
The flowers are designed to foster cross-pollination between plants. Thus, it is wise to grow 2 plants of each species. The features of the flower are shown in Fig 5-2. Pollen must be transferred from pistil to stigma a few days after the flowers open. The stigma is an elongated flap-like structure that covers the anthers, with its pollen receptive surface on the side away from the anthers. With care, the flap or stigma can be bent to the front, exposing the anthers which may be examined for pollen development. A small brush, or better yet a toothpick, is used to transfer the pollen. The flowers of some species are quite small so it is sometimes easier to tear open the corolla or to remove most of it in order to expose the stigma. The corolla is the tubelike part of the flower that is made up of the fused or joined petals. If pollination has been successful the ovary will start to swell in a week or two. The mature seed pods will split open to release the seed about 4 weeks after pollination.
Seed to be stored should be dried at room temperature for a few days and then placed in sealed vials or plastic bags and kept under refrigeration. The seeds of the temperate species of Pinguicula require stratification before they will germinate. For best results, the period of stratification for each of the species should be at least equal to the minimum period of plant dormancy.
Fig. 5-3 Winter bud of Pinguicula with smaller brood bodies which should be removed and planted separately. They grow into new plants.
Subtropical and Tropical Pinguicula __
About Va of these species have been successfully cultivated to date. Those for which there is cultural data available have been divided into groups, by the similarity of their cultural requirements.
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