This section is from the book "Manual Of Gardening", by L. H. Bailey. Also available from Amazon: Manual of Gardening.
A tuberqus-rooted, well-known conservatory or window plant, blooming in summer. Excellent for porch and yard decoration.
It lends itself to many conditions and proves satisfactory a large part of the year, the leaves forming a green arch over the pot, covering it entirely in a well-grown specimen. The flowers are borne in a large cluster on stems growing 2-3 ft. high, as many as two or three hundred bright blue flowers often forming on a single plant. A large, well-grown plant throws up a number of flower-stalks through the early season.
The one essential to free growth is an abundance of water and an occasional application of manure water. Propagation is effected by division of the offsets, which may be broken from the main plant in early spring. After flowering, gradually lessen the quantity of water until they are placed in winter quarters, which should be a position free from frost and moderately dry. The agapanthus, being a heavy feeder, should be grown in strong loam to which is added well-rotted manure and a little sand. When dormant, the roots will withstand a little frost.
 
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