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Parigo Horticultural

Cultural Guide for Cut Flowers

Cropping Programme

    Alstroemeria can be planted throughout the year as a means of staggering the onset of the first flowering flush. However, the most popular planting times are September to November for an early spring production, and March to June for production to begin in the autumn and winter. An average time from planting to flowering would be 3 months; depending on the season. Most modern varieties of Alstroemeria will continue to produce flowers, under normal conditions, throughout the whole year.

    Although most of this guide has been written with a glasshouse crop in mind, the same principles are applicable to an outdoor crop. This can be planted any time after the last frost, but is best planted before July so that the crop is well established by winter. It is recommended that the crop is mulched for its first winter, but it should be capable of surviving subsequent winters unaided. A flowering season of Mid June to October or November can be expected. (Back to Top)

Soil Preparation

    Alstroemeria require an open, well drained soil. The crop is deep rooting and cultivation to a depth of 40-50 cm is necessary. Adequate organic matter should be incorporated and the site sterilised, using steam or methyl bromide. (If methyl bromide is used the soil should be left for approx. a week before planting). Alstroemeria like a slightly acidic soil, a pH of 6.5 being ideal. Mixing in coarse peat as a soil conditioner is very beneficial.

    Soil analysis should be used as a guide to determine the amount of base dressing to apply. In general, low nitrogen, moderate phosphate, and high potash is required. If high salt levels occur in the soil, these have first to be reduced by leaching with clear water. (Yield of Alstroemeria begins to be depressed at a salinity of 0.8dS/m). (Back to Top)


    Plant in beds 100-112 cm wide with paths at least 50 cm wide. Plant 2 rows per bed with 40-45 cm between the rows. Spacing in the row should be 35-45 cm depending on the variety. Planting depths should be such that the top of the pot is at soil level. The planting density is around 5 plants per square metre of bed. (Back to Top)


    To encourage rapid root growth, a minimum temperature of at least 14C should be given for the first few weeks after planting. During the autumn and winter a minimum temperature of 10-12C should be maintained if flower production is to be encouraged during this period. When light levels are poor the minimum temperature can be reduced to 7-8C.

    Ventilation temperature should be 16-18C. As the spring crop develops and light levels improve, the minimum temperature can be allowed to rise. It is important to give sufficient ventilation to maintain humidity and a buoyant atmosphere. Rapid fluctuations in humidity can cause plant stress and severe leaf tip scorch on some varieties. During the late spring and summer period the crop should be kept cool. Ideally the soil temperature should not rise above 20 C. Shading at this stage is beneficial. ( Back to Top )

Watering and Feeding

    Water plants in well after planting. During full growth the soil should be kept reasonably moist. In the winter period watering can be reduced significantly. Liquid feed should be commenced when the crop is growing actively using a balanced nitrogen and potash feed.

    Soil analysis should be used as a guide to determine the feeding programme, particularly when the crop is more than one year old and a nutrient balance may need correcting. As a guide, a 1:0:1 feed in the summer and 1:0:2 in the winter may be considered standard.    ( Back to Top )

Crop Supports

    It is important that the crop is properly supported. Strong end supports are required with intermediate cross supports spaced approximately every 3 metres.

    At least three nets should be used, with more for taller varieties. The bottom net can be at 12.5 cm2 mesh, with the upper nets at least 20 cm2 to make harvesting easier. The nets should be spaced 30-35 cm apart. The top net will need to be at a height of about 150 cm for the taller varieties, and the bottom net should be sufficiently low to avoid excessive tucking in of new shoots. ( Back to Top)


    Newer varieties should not require thinning, but with the older varieties it is desirable to pull out the non-flowering stems during the growing season, always leaving enough growth to sustain the plant. Carried out on a routine basis, thinning will improve the strength and quality of the flowers and keep the plant open with good access for light and air movement.

    The frequency and amount of thinning will vary with the variety and age of the crop.

    A newly planted crop should be thinned once the plants are established, and then periodically as the flush develops. Older crops will need more thinning out to maintain good quality flowering stems.

    Another method of checking thin growth is by pinching out the top of the stem. This is less labour intensive and discourages excessive re-growth of non-flowering stems.
    It is probably best to use this method in combination with pulling out. (
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    Alstroemeria are day length sensitive and a flush of flowers can be advanced in short day conditions by lighting. Satisfactory results can be achieved by giving a 13 hour day at a light intensity within the range of 50 - 160 lux, from mid September to mid November for an autumn flush and the end of December to late March for a spring flush. A day length extension gives better results than a night break.
    Day lengths in excess of 14 hours can lead to the prevention of shoot initiation, particularly at low temperatures.
    Photoperiodic lighting with tungsten filament lamps will not improve flower quality or prevent bud abortion in susceptible varieties. (
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    Stems should be harvested when the first bud is either partially or fully open, depending on customer requirements. Stems can be cut or pulled (providing that no piece of rhizome is pulled from the ground with the stem, which would damage the plant). With the plants being well established in the ground pulling the stems may lead to an increase in flower production. If stems are cut the old flower stumps should be removed at the end of the crop.

    After harvesting the flowers should be placed in water as soon as possible, especially during warm sunny weather. Flowers can be stored for a few days if necessary in a cold store at 2-3C. A flower conditioner should be used to improve vase life.

    Grading standards will depend upon marketing requirements, but generally a top grade requires a minimum of 5 heads with lower grades proportionally less. ( Back to Top )

Deficiency disorders

    Iron deficiency can cause a yellowing of the foliage in the head of the young shoots. This can be corrected by the use of iron chelate as a wet spray or a soil drench.

    Manganese deficiency can cause yellowing of the leaf lamina between the leaf veins, mainly on the young leaves. A foliar spray with Manganese sulphate during dull weather will give the best results.

    Magnesium deficiency can cause leaf discoloration in the older leaves. Spray with a solution of Magnesium sulphate. ( Back to Top)

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