318 THE GREENHOUSE. [CHi?. XL 



being cut out, so that the wood which is to 

 produce the flowering shoots should never be 

 more than two, or at most three, years old. 

 Cuttings strike readily at any season when the 

 plant is in a growing state; if put into a rich 

 soil and kept moist, they will root in a fortnight, 

 and flower in a month. The flowers of the 

 hydrangea, though generally pink, are some- 

 times blue ; and the art of making them blue 

 at pleasure, has long been a desideratum among 

 gardeners. A great number of recipes for this 

 purpose have been given in gardening books; 

 but, though all of them are occasionally suc- 

 cessful, none of them will insure success. 

 Sometimes, transplanting hydrangeas that have 

 been grown in loam into peat will have the 

 desired effect ; and, at others, watering with 

 water in which iron has been steeped will 

 change the colour of the flowers. The fer- 

 ruginous yellow loams of Hampstead Heath 

 and Stanmore Common are almost always effi- 

 cacious, but even these have been known some- 

 times to fail. All that is known with certainty 

 is, that the change of colour is only a variation, 

 and not permanent ; as cuttings taken from a 

 blue hydrangea, and planted in common soil, 

 almost always produce pink flowers. In 

 Devonshire and Cornwall the hydrangeas grow 

 to an enormous size in the open ground, and 

 frequently produce blue and pink flowers on 

 the same plants; and in the latter county, near 

 the lead mines, the flowers are generally of a 

 most brilliant blue, without any care being 

 taken to make them so, though the soil does 

 not appear to have any effect on the colour of 

 other pink or rose-coloured flowers. 



