Cultivation Instruction for Hyacinth

Chapter I very early flowers. The leaf-formation period is accelerated by higher temperature during the bulb's cultivation stage, hereby starting the TEMPERATURE flower formation period earlier. In contrast to other bulbous plants, early flower- TREATMENT formation in the hyacinth is achieved by providing specific temperatures. One way of achieving Introduction this is to increase the temperature of the soil in which the bulbs are grown ("Herald hyacinths"). The hyacinth has it's origins in Asia Minor, and Because of its expense, this method is very rarely the current Dutch cultivars have descended from used. More commonly, the bulbs are lifted early Hyacinthus orientalis, a blue species imported and then given a temperature treatment in an around the middle of the 16th century. A mem- air-conditioned chamber to advance flower for- ber of the Liliaceae family, the hyacinth over- mation. The lifting date and temperature treat- winters in the form of a scaled bulb. ment are the factors which separate the two Applying temperature treatments to produce methods of production pot and cut flowers. hyacinths in greenhouses was introduced at the beginning of this century. Prepared hyacinths Like the tulip and several other bulbous plants, Bulbs are lifted around 20 June after which a the hyacinth does not produce a high quality specific sequence of temperatures is applied to flower nor sufficient stem length until the bulb is advance flower formation, Depending on where exposed to a period of low temperature. the bulbs are grown, the cultivar and the lifting date, the flower is completely formed during the Uses for the hyacinth second half of August. In technical terms, this is described as having reached "Stage G". Since The hyacinth is marketed in either pots or as a the hyacinth has a flower cluster, this stage is not cut flower. reached until the last floret is differentiated. The stem elongation period can then proceed. Pot hyacinths Prepared hyacinth bulbs are used for producing One or more bulbs are planted in a pot, and a pot plants intended to bloom until late temperature treatment is used to force the bulbs December, and cut blooms until mid-January. into flower. Pot hyacinths are usually marketed when the lowermost florets of the flower cluster Unprepared hyacinths begin to separate. If taken from the greenhouse Bulbs are tifted later (after 20 June) and receive before the plants reach this stage, the plants are a temperature which encourages optimal (less called "sprouted hyacinths". Although various advanced) flower formation. During this treat- bulb sizes are used for pot production, the usual ment period, Stage G is reached, although this sizes are 17/18, 18/19 and 19+ (cm.). occurs much later than in prepared bulbs. The temperature is maintained until it is necessary to Cut hyacinths start the stem elongation period. This means For production of cut flowers, the bulbs are that after Stage G is reached, a growth-retarding planted in forcing boxes and, a~s above, forced temperature is applied. into flower by use of a temperature treatment. With unprepared bulbs, less importance is Various bulb sizes can also be used for this type attached to when Stage G is reached. This is of of production, but sizes 15/16. 16/17 and less concern despite the fact that Stage G will 17/18 (cm.) are preferred. sometimes not have been reached when the stem elongation period begins. Since the bulbs Temperature treatment are less advanced, this causes no problems later in cultivation. Unprepared hyacinth bulbs are The growth cycle of the hyacinth bulb encom- used as pot hyacinths for flowering after l passes distinctive periods - leaf formation, flower January and for cut flowers after mid-January. formation and stem elongation. Forcing is achieved by advancing the flower-formation period and then providing the most effective type of cold period. This is why hyacinth bulbs grown in mediterranean countries are used to produce A-2-1 Intermediate temperature Chapter II For prepared bulbs, a temperature of 17°C is maintained after Stage G is reached. This STEPS IN PLANTING encourages the hyacinth to enter the stem elongation period. In spite of the fact that the flower- POT HYACINTHS formation period is over, the intermediate temperature still has an effect on flower quality; General at a temperature of 17°C, this effect is definitely beneficial. An intermediate temperature lower Concerning the subject greenhouse, trays/con- than 17°C is inadvisable due to a sharply tainers and potting soil we refer to Chapter IV of increased risk of Penicillium and a somewhat the tulips. negative effect on the quality of the forced hyacinths. The risk of green or desiccated florets Arrival at the top of the flower cluster increases, a problem which encourages the development of blind Prepared hyacinths should be planted immedi- florets and bud rot. ately upon arrival. If the bulbs must be stored, For unprepared hyacinths, the intermediate tem- they should be placed in open containers (trays) perature starts four weeks before planting, at and stored in a ventilated room at 17-2CTC. The which time stem elongation begins. If planted amount of ventilation can be calculated as fol- after 15 December, a temperature of 25°C is io WS: maintained instead of 17°C until planting; this is - at 17 'C, 2 mVhour/100 litres of bulbs; done to prevent root formation and subsequent - at 20°C, 6-10 mVhour/100 litres of bulbs. Penicilliitm attack. The following cold period Temperatures higher than those indicated have a wil! however, have to be extended by 1-2 weeks. delaying effect on the development of the flower. Temperatures under 17"C cause a higher r.h. - an factor which leads to a much increased risk in PeniciUmm attack in parts of the bulb such as the emerging roots. This can then have a negative effect on the quality of the flowers. Unprepared hyacinths should be stored as fol- io WS: - at 23-25°C, 6-10 mVhour/100 litres of bulbs and 4 weeks prior to planting; - at 17°C, 2 mVhour/100 litres of bulbs. Planting time When to plant hyacinth bulbs depends on several factors: - Their preparation. The best time to box-up prepared bulbs is during the second half of September. Unprepared bulbs are planted from October. - Storage during the cold period. If the bulbs are stored in a rooting room which is not air-conditioned or in an outdoor storage clamp, they cannot be planted until the ambient temperature has fallen to 13°C or lower (optimal temperature: 9"C). Higher ternperatures cause poor rooting, an increased risk of Fusarium attack, and a slow down in growth. Storing bulbs at 13°C for a few weeks immediately before planting is acceptable. - Required flowering period. By counting back the number of weeks from the required flower- A-2-2 ing period, the right planting date can be cal- bulbs at planting, the bulbs can be wetted by culated. spraying them Jmmediatety before planting. - The required cold period per cultivar and time Dipping them is highly inadvisable because of of year. the risk for an Erwinia attack. When planting, fill - Cultivar. Not every cultivar is suitable for every the pots completely with soil and push the bulbs planting period. In addition to the duration of into the soil. One point to remember is that the flower development period and the length hyacinths always have the tendency to push their of the cold period, other factors include prob- way upward out of the pot as a result of osmot- lems with plants becoming too tall and too limp ic pressure. Bulbs planted later in the season in the greenhouse. tend to do this more than those planted first. To avoid this problem with bulbs in the rooting Planting method room, add a layer of coarse sand (min. 3 cm.) on top of the bulbs, or put a foam cover over them. Planting one or 3-5 bulbs per pot is preferred. Growers also place racks over the bulbs for this The bottom of the pots has to have drainage purpose, After three to four weeks the bulbs are holes. There are a nurnber of soil types or mix- sufficiently rooted, and these racks must be tures with a pH of 6-7 that can serve as filler in removed to avoid damaging the shoots. The the pots. To avoid skin irritation during handling racks can be reused for the next forcing. A-2-3 CHAPTER III ROOTING ROOM AND STANDING GROUND Rooting room After potting up, the pots can be placed in a rooting room, leaving enough space for shoot growth. Temperature The ideal temperature for hyacinths is a constant temperature of 9"C throughout the required cold period. This temperature should commerce immediately after the bulbs are planted. If, how- Planting density depends on pot size, but the ever, a rooting room without air-conditioning is maximum is 200 bulbs per m2. After planting, used, a starting temperature of 10-13°C is the pots should be fairly well watered but not to acceptible. After one to two weeks, however, the excess. An over-wet potting soil reduces the temperature must be dropped to 9°C. If not, this quality of the rooting environment. This increas- lack of cold will have to be cornpensated for at es the risk of a Pythium attack in the roots. the end of the cold period. Hyacinths are usually placed in the same rooting room as tulips. Table l indicates the optimal cold temperatures for the box forcing of tulips.

Load more