P. Indispensable rock plants which appreciate limy soil and sun with one important exception — the trailing Lithospermum dijfusum (prostratum) usually demands lime-free soil. Grace Ward is gentian-blue and Heavenly Blue rather paler. Both bloom very freely in late spring and early summer, growing to about 4 in. Lithospermum intermedium (Moltkia intermedia) blooms later with deep blueon a 9 in. plant. All are suitable for dry walls. Increase by in July.