FORCING 



FORCING 



1265 



Forcing hardy plants. 



Forcing is an economical method of securing large 

 quantities of flowers in winter; it is extensively used by 

 commercial florists for cut-flowers and flowering plants. 

 Plants usually forced are hyacinths, tulips, narcissi and 

 other Dutch bulbs, lily-of-the-valley, astilbe, dicentra, 

 hybrid perpetual and rambler roses, Deutzia gracilis, 

 hybrid rhododendrons (R. sinense) and Ghent azaleas, 

 tender hydrangeas and lilacs. 



This mode of procuring flowers at small cost has 

 always been more or less in vogue among plantsmen, 



and of late years 

 has received fresh 

 impetus, owing to 

 the heavy demands 

 for decorative 

 plants at Easter. It 

 is not only an in- 

 expensive method of 

 getting flowers, but 

 with most plants, 

 after a little experi- 

 ence, the time of 

 blooming can be 



flower-buds. Close pruning is necessary, and root- 

 pruning is helpful. Grafting, which has a tendency to 

 dwarf and hasten maturity, is also used with strong 

 growers. Sometimes both growing in pots and grafting 

 are employed, as in lilacs. 



A plant fit for forcing must be compact, both top and 

 roots; economy in space is essential. It is now possible 

 to secure from the French, Dutch and Belgian nurseries 

 many plants grown for this purpose. A few come pot- 

 grown, but most of them are from the open ground: 

 very little of this work is done in American nurseries. 

 Figs. 1553-1555 show the methods of preparing woody 

 plants for forcing. 



Herbaceous plants should be prepared for forcing 

 with equal care, and the process may require several 

 years. The removal of the flower-buds and growth, 

 under high cultivation, in close, compact clumps, 

 apparently produces the same results that pruning 

 and grafting accomplish for trees and shrubs. Fig. 

 1556 shows the root-clump of an herb prepared for 

 forcing. 



Plants that have once been forced are commonly 

 thrown away. It is generally cheaper to buy new stock, 

 but lilacs, azaleas, and the like, can be planted out 

 and will recover sufficient strength in two years for a 

 second forcing, or for other use. 

 Some species, like Viburnum 

 plicatum, staphylea, and xantho- 

 ceras, if grown on in pots after 

 forcing, may be again forced, and 

 seem to do better the second year. 

 This is probably explained by 

 the fact that insufficient prep- 

 aration was given for the first 



1553. Azalea, received from Europe, now 

 pruned for forcing. 



easily calculated. The process has 

 limitations, at any rate with our pre- 

 sent knowledge of the matter, inasmuch 

 as, with the exception of "retarded 

 plants" and a few bulbs, it is not 

 practicable in late autumn and early 

 winter without the use of ether. It is 

 possible, however, that by using "re- 

 tarded plants," i.e., plants held over 

 their natural time of flowering by 

 keeping them in cold storage at a temperature suffi- 

 ciently low to prevent growth, this difficulty may 

 eventually be overcome. Except, however, with lily- 

 of-the-valley, which is admirably adapted to this prac- 

 tice, little is known of the possibilities of this form of 

 forcing; it is hoped that other plants, equally useful, 

 may be treated in this way. It is evident that, on 

 account of the cost of storage, bulky plants could not 

 be handled. 



The requirements for successful forcing are: (1) a 

 good knowledge of the plants; (2) proper preparation; 

 (3) a period of rest; and (4) proper care after the plants 

 are brought into heat. 



Those plants force most easily which bloom in spring 

 and early summer. Late-blooming kinds, like Rhodo- 

 dendron maximum, clethra and Hydrangea paniculata 

 var. grandiflora, do not give good results. No success is 

 obtained with asters and goldenrod, unless they are 

 retarded. These points must be studied out by the 

 grower. 



Trees and shrubs should be specially prepared for 

 forcing by careful cultivation for one or two years 

 before use. They can be planted out-of-doors, with 

 plenty of room to develop, or they can be grown in 

 pots, the latter method being used with vigorous plants, 

 which are apt to run to growth without developing 



81 



1554. Rhododendron, received from Europe, 

 ready for forcing. 



trial, the first forcing 

 being really "proper pre- 

 paration" for the second 

 forcing. 



Hardy plants must 

 have a period of rest for 

 successful forcing, the 

 time required vary- 

 ing in different 

 species. One can- 

 not tell, except by 

 experiment, that 

 Paper White nar- 

 cissi will force easily 



1555. Lilac pruned for forcing. 



in November and December, while the double Von Sion 

 will not; the individual equation of each kind is an 

 element which must be considered. There is a popular 

 notion that freezing will shorten the time for resting, 

 or, at any rate, is conducive to the welfare of the plant. 

 This idea does not seem to stand any practical test. 

 After potting, do not subject the plants to severe 

 frosts (10 to 12 F.), or else the roots, now much 

 exposed, may suffer. The large buds of lilac and 

 rhododendron may also be injured if frozen hard. 



Pot the plants as soon as they ripen their growth in 

 autumn, beginning in September with herbaceous stock, 



