88 
its being less commonly seen in collections than the rose col- 
oured. Its value has been further enhanced by the mystifica- 
tion of culture and supposed difficulty in obtaining flowers of 
that colour. This may, probably, be done by various processes. 
The colour is not, however, likely to continue beyond one sea- 
son, when the means used to obtain it have been by any ingre- 
dients, given in a liquid state ; unless the application be repeat- 
ed every year. A fine blue colour may be obtained by grow- 
ing the j)lauts entirely in good heath mould. This may be 
done by potting young-rooted cuttings in that soil, or by re- 
moving all the soil from old plants, and repotting them with 
heath mould. The blue colour is generally obtained in the first 
season, to a certainty in the second, and w ill continue as long as 
that soil is used. It would be an interesting subject for inves- 
tigation to ascertain how the colour is changed by the use of 
heath mould, as it does not appear to have the same efiect upon 
other plants. As the Hydrangea is hardy the change may be 
produced by planting them out amongst the American plants. 
Various ingredients have been added to common soil to effect 
the same purpose ; these we intend to notice in a future number. 
127 Artichokes, to improve. Running small pieces of lath, or 
splinters of any wood through the flower stems, within 4 in. of 
the flower oi head, at right angles to the stem, and keeping the 
wound open, retards the opening of the flower, and makes the 
head nearly double the ordinary size.” This is a German prac- 
tice, and seems to operate, like ringing trees, by impeding the 
return of the sap, and so stagnating it in the head. 
128 Roses, CULTURE of. In a well-arranged catalogue of Roses 
byT. Rivers, jun. of Sawbridgeworth, are some useful observa- 
tions on this universally admired genus. As a few of the ideas 
are original, we shall give them further publicity. He says, “I 
still think, that, in unfavourable soils, Roses require being re- 
moved, and their roots trimmed every third or fourth year. In 
cold clayey soils, the best compost for them is rotten manure and 
pit sand; in warm dry soils, cool loam in lieu of sand; annu- 
al pruning which is quite essential, should always be done in 
October, or in March ; but October pruning will be found greatly 
advantageous as the Rose will then prepare itself during the re- 
mainder of the autumn, for vigorous growth in spring. The 
families of roses are now so well defined, that each ought to 
127» Card. Mag. Vol. 11, 41. 
