This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
For sixty years or more the Lily of the Valley has been a favourite flower with market growers, but there are millions grown now where there were only hundreds grown half a century ago. Indeed there are now many thousands of acres of land on the Continent and in the British Islands solely devoted to the cultivation of Lily of the Valley "crowns", and the trade has been encouraged largely by the introduction of the refrigerating or retarding system into horticulture. Lilies of the Valley can now be had in bloom at all seasons of the year, either by forcing them in winter or retarding them in summer (fig. 218).
To secure the finest crowns for forcing, growers prefer a light sandy soil that is naturally cool and moist, but yet well drained. In such a soil the finest forcing crowns are produced after two or three years of cultivation. From August to December large purchases are made by. growers, the "Berlin" variety being largely used for winter and early spring work. From October onwards the crowns are placed in pots or kipper boxes, the tops of the crowns being flush with the top of the receptacles. A light sifted soil of almost any description is used, and worked in between the crowns. About one dozen are put into a 5-in. pot; but in boxes the crowns are placed about 1 in. apart every way. The plants are then given a good watering, and if it is intended to force them at once, they are plunged up to the rims in beds of coconut fibre, moss, or leaf mould, and perhaps a layer of moss 3 or 4 in. thick is placed over them. The temperature is kept up between 80° and 95° F., and care is taken never to let it drop below 80° or to rise above 100°. The beds or chambers in which the plants are placed should be perfectly dark, and this is best done by placing boarded lights over them. Water must be given in great abundance each day, taking care that it is of the same temperature - say 80° F. - as the bed in which the plants are placed.
Fig. 218. - Lily of the Valley forced for Market.
When the shoots are about 2 or 3 in. high the moss is taken off the tops and a little light is admitted gradually. As soon as the blossoms appear, overhead watering is discontinued, and the plants are moved from the forcing bed to a somewhat cooler place and receive more light. Other batches then take their place in the forcing chamber. Before Christmas it takes from three to four weeks to force Lilies of the Valley into bloom, but the time is reduced to three weeks and less with the turn of the year.
This process consists in placing the crowns in refrigerating chambers having a temperature of 28° to 30° F., just low enough to keep the plants in a dormant condition without injury. During the summer months the crowns are taken out as required and put into pots or boxes in light soil. They soon start into growth in a greenhouse without being forced, and only require attention to watering, etc, daily. There are shown on the accompanying plate (1) how the crowns are packed in bundles in the refrigerators; (2) how they are potted up; (3) the growth made at the end of a fortnight; and (4) the plants in full bloom at the end of three weeks. While the Berlin variety is the best for forcing, the "Fortin" variety and the "Victoria" are best for retarded blooms.
RETARDED LILIES-LONGIFLORUM AND SPECIOSUM (LANCIFOLIUM) AT THOMAS.
ROCHFORD & SON'S NURSERY.
RETARDED LILY OF THE VALLEY Showing different stages of growth.
Photos. Chas. L. Clarke.
A good trade is done in Lilies of the Valley grown naturally in the open air. The best time to plant is in early autumn - September if possible - and cool, sheltered spots should be chosen. The soil should be of a light sandy loam, naturally moist, but well drained, deeply dug, and well manured. Between rows of widely planted standard fruit trees is a good place to make up Lily of the Valley beds. The crowns should be planted 2-3 in. apart in straight rows about 6 in. apart, and the beds should not be more than 4½-5 ft. wide, having an alley 12-18 in. between. The tops of the crowns should be about 1 in. below the surface, and after the beds are planted they may be mulched with a good dressing of well-rotted manure. About March and April lights may be placed over the beds. This will not only hasten the plants into early bloom, but will also protect the flowers from damage by rain and wind, and give them a purity of colour otherwise unattainable. When picking the flowers, the stem should be pulled clean out its entire length with a kind of jerk. Each year it will pay to give a good dressing of well-rotted manure to the beds in early autumn.
No flower pays so well to grade as Lily of the Valley, whether forced, retarded, or natural, and the grower who adopts this course will find a great difference in his receipts.