394 



Gardening for Amateurs 



name of Chinese Balloon Flower. The plants 

 grow about 18 inches high ; as the flowers 

 are rather large and heavy, the stems should 

 be supported by a few twiggy sticks. The 

 deep blue flowers are at their best during 

 July and August. There is a white variety, 

 album ; Mariesii, rich blue ; and M. album, 

 white. The Platycodons are delightful 

 for planting in groups along the front of 

 a sunny border and in the rock garden in 

 rather light ground in which leaf-soil is 

 freely mixed. Seeds should be sown in a 

 cold frame and the seedlings grown in 

 boxes until planted out. April or May is 

 a good time to sow seeds. Platycodons do 

 not like being disturbed at the root, though 

 if replanting becomes necessary April is the 

 time to do it. 



Polemonium (Jacob's Ladder). P. 

 coeruleum is the best-known sort, and has 

 long been a favourite perennial in gardens. 

 The plants grow l to 2 feet high, have 

 elegant leaves and pale blue flowers open- 

 ing from May to July. There is a white 

 variety album and another variegatum 

 with prettily marked leaves. For variety 

 the following may also be grown : P. flavum, 

 tawny-yellow, 2 feet, June to August ; P. 

 humile (syn. Richardsoni), sky-blue, 1 foot 

 to 1^ feet high, May to July ; and P. humile 

 album, white with yellow centre. The 

 Jacob's Ladder is increased by division of 

 the roots in autumn or spring, and from 

 seeds sown on a border outside from April to 

 June. The plants thrive best in a rather 

 light soil, such as one finds in old-fashioned 

 gardens, where digging and manuring have 

 been practised for years. In heavy, ill- 

 drained ground P. humile and its variety 

 album find a place in many rock gardens. 



Polygonum (Knotweed). Though most 

 of the Knotweeds are unsuited for cultiva- 

 tion in the herbaceous border proper, there 

 are few gardens where they cannot be 

 planted with pleasing effect. The peren- 

 nial kinds vary in height from about 6 

 inches to 10 or 12 feet, so their uses in the 

 garden are many and varied. All are of easy 

 cultivation, and thrive in ordinary soils. 

 They are readily increased by division of the 

 clumps from October to March, when the 

 ground is suitable for planting. P. afnne 

 grows 6 inches to 1 foot high, forming a 



pretty carpet of green leaves, which change 

 to a bronze tint in autumn, and retain their 

 colour during the winter. From July to 

 September the plants produce a pleasing 

 display of rose-pink flowers in spikes. This 

 dwarf Knotweed, which is also known as P. 

 Brunonis, forms a very pretty edging to a 

 shrubbery border, an attractive carpet for a 

 dry bank, and is also useful in the rock 

 garden. P. amplexicaule grows 2 to 3 feet 

 high, and has rose-red flowers in autumn ; 

 P. Bistorta (Adderwort), If feet high, bears 

 reddish-pink flowers from June to August ; 

 var. superba is brighter. P. compactum, 

 2 to 3 feet high, has creamy-white drooping 

 flowers in August and September ; it is a 

 desirable plant to brighten odd corners and 

 for half -shady shrubbery borders. P. cus- 

 pidatum is a plant for the woodland, shrub- 

 bery borders, and wild garden ; the root- 

 stocks increase rapidly, and soon spread 

 over the surrounding ground, and the 

 annual stems rise to a height of 6 to 10 

 feet ; the creamy-white flowers develop in 

 late summer from the axils of the leaves. P. 

 polystachyum, 4 feet high, bears white frag- 

 rant plumes in August and September ; it is 

 a good herbaceous plant for large borders. 

 P. Sachalinense, the tallest growing of the 

 herbaceous Knotweeds, 8 to 12 feet high, 

 has large leaves and arching stems, and 

 bears creamy-white flowers in autumn. P. 

 vacciniifolium is a dwarf Knotweed, 6 to 

 9 inches high, valuable as an edging to a 

 shrubbery border and for the rock garden ; 

 it yields rose-pink flowers in autumn. 



Potentilla (Ginquefoil). The Poten- 

 tillas or Cinquefoils are attractive, hardy 

 plants, flowering practically throughout sum- 

 mer and autumn. For beds and borders the 

 double varieties obtained by crossing P. ar- 

 gyrophylla atrosanguinea and P. Nepalensis 

 are the most showy, though two or three of 

 the type kinds should also find a place in 

 gardens. Except where stated, the Cinque- 

 foils are from 1 to 2 feet high. They are 

 easily grown, thriving perhaps best in rich, 

 well-drained sandy soil in sunny positions ; 

 they may be planted in autumn or spring. 

 Propagation is effected by division of the 

 clumps in autumn or spring, and by seeds 

 sown in a cold frame or on a fine seed-bed 

 prepared out of doors from April to June. 



