POTTING 



PRENANTHES 



1427 



Drainage is necessary in all pots over 4-inch and for 

 hard-wooded plants even that size is better drained. 

 This is technically called "crocking," i. e., placing pots- 

 herds in the bottom of the pot to allow the quick pas- 

 sage of water and admit air to the roots. I'lace a large 

 piece over the hole in the bottom of the pot and the 

 remainder in smaller pieces. There are usually enough 

 broken pots around a place to supply the needs. Char- 

 coal is an excellent material for supplying pot drainage, 

 none better. An inch or so of drainage is sufficient in 

 a 5- or (J-inch pot, two inches or so for all sizes above 

 these. A bottom of broken stone, cinders or gravel is 

 essential upon which to stand the pots, as such a stratum 

 accelerates drainage, while at the same time providing 

 a moist surface so beneficial to plants in a greenhouse. 



A few words of caution may not be out of place 

 before closing this branch of the subject. Never shift 



plants well set with good flowers are wanted; and in 

 these days such plants will bring enough in the best 

 markets to pay for the space and trouble. For 2- and 

 3-inch pots use sifted soil, but for 4-inch and over soil 

 well broken, but having plenty of fiber from sod in it, 

 should be used. Always water plants thoroughly after 

 shifting so as to soak the soil to the bottom, and do not 

 water again until they show dryness half way down the 

 pot on the outside. Patrick O'Mara. 



POUKRETIA. See Puya. 

 POURTHiaiA villosa. See Photinia. 

 PRAIRIE CLOVER. Petalostemon. 

 PRAIRIE DOCK. SUphium (erebinthinaceum. 





X 



^- 



':.'"'ij'^'C:; 



1946. Too deep. 



1947. Too hish. 



1948. Pot too full. 



1949. Good. 



plants while the ball of soil is wet; it should be dry 

 enough to crumble readily to the touch. Never shift 

 into dirty pots; it will pay to clean them, especially the 

 inside. Never shift a pot-bound plant without loosen- 

 ing the soil on the surface of the ball. A few smart 

 raps with the closed fist will do it; or better still repot 

 as now described 



Repotting is necessary frequently when plants have 

 become pot-bound, or when from any cause they appear 

 to require it; such, for instance, as debility from over- 

 shifting, over-watering or neglect of any kind. In 

 such cases the soil should be washed from the roots 

 almost entirely and the plant put into a pot a size or 

 two smaller than it has been growing in, taking care to 

 firm the soil well, and if a shrubby plant prune it back 

 according to its needs and condition. Shade such 

 plants until danger of wilting is past and water spar- 

 ingly until new and vigorous growths appear, showing 

 that the subjects have regained their normal health. 



There are a few cultural details intimately associated 

 with potting which may with profit be added as a 

 closing paragraph. The high, narrow pot shown on 

 the extreme right of the line of pots in Fig. 1937 is fre- 

 quently used for roses and palms by some, especially 

 for Cocos Weddelliana, which makes a long tap-root 

 and which it is almost invariably fatal to break. It is 

 feasible, however, to avoid this if the seeds are sown 

 in 6-inch pots, using 4 inches of clinkers as a bottom. 

 These check the downward growth and Induce develop- 

 ment of fibrous roots in the soil, so that the tap-root 

 may be cut off below them and the ordinary 2-inch pot 

 used with safety. It is not necessary to use the deep 

 pot for roses in any case. Plants which exceed the 

 diameter of the pot should be given room to allow for 

 development. The best market growers plunge the 

 pots in soil to half their depth, as it is necessary in the 

 spring months because of the rapid evaporation of 

 water. This refers especially to geraniums, fuchsias, 

 heliotropes, petunias, etc. Care must be taken, how- 

 ever, to lift them occasionally so as to prevent the roots 

 from getting hold in the soil through the hole in the 

 bottom of the pot. Ten inches apart from center to 

 center for such plants will not be too much if stocky 



FRENANTHES (Greek words, meaning drooping 

 blossom). Compdsitip. Rattlesnake Root. A genus 

 of about 16 species of tall perennial herbs, of which 10 

 are natives of North America. A few species are offered 

 by collectors. Prenanthes are leafy-stemmed plants 

 with dull colored heads borne in spike-like terminal 

 panicles. Lvs. alternate, lower ones petiolate, sagittate, 

 cordate, often much divided: upper ones auriculate and 

 much narrower and smaller heads: 5-30-fld. : akenes 

 terete, 4-5-angled, usually striate. The species are ex- 

 tremely variable. They are of easy culture in any good 

 soil. 



A. Involucre glabrous. 



B. Heads 5-1-fld.: involucre very narrow, only 1 line 



thick, 



altlssima, Linn. A variable species. Stem 3-7 ft., 

 slender: fls. greenish yellow; pappus straw-colored or 

 whitish. Julj'-Oct. In open or shade, Canada to Ga. 

 and Tenn, 



BB. Reads 8-lG-fld.: involucre broader, 1%-S lines 



thick. 



c. Pappus deep cinnamon-brown. 



&lba, Linn. Stem 2-5 ft. high, usually purplish: in- 

 florescence thyrsoid-paniculate: fls. dull white. Aug., 

 Sept. Open woods and sandy soil, Canada to Ga. and 

 111. B.B. 3:289. Mn. 3:161. 



cc. Pappus straw-colored. 



serpentS,ria, Pursh [Ndbahis Frdzeri, DC). Stem 

 usually about 2-4 ft. high, sometimes purple spotted: 

 fls. purplish, greenish white or vellowish. July-Oct. 

 Ont. to Fla. and Ky. B.B. 3:289. " 



aa. Involucre hirsute-pubescent. 



racenidsa, Michx. Stem 6 in. to 2 ft. high: stem-lvs. 

 mainly sessile, while they are mostly petiolate in the 

 other species here described: fls. purplish. Aug., Sepr. 

 Moist open places, Canada to N. J. and Colo. B.B. 

 3 -SI- p. W. Barclay. 



