This section is from the book "A Dictionary Of Modern Gardening", by George William Johnson, David Landreth. Also available from Amazon: The Winter Harvest Handbook: Year Round Vegetable Production Using Deep Organic Techniques and Unheated Greenhouses.
Salvia officinalis.
The Common Green; Wormwood; Green, with variegated leaves; Red, with variegated leaves; Painted or Parti-coloured: Spanish or Lavender leaved; and Red.
A dry moderately fertile soil is best suited to their growth, in a sheltered situation.
These may be either of the preceding or same year's growth; if of the first, plant in April, but if of the latter, not until the close of May or middle of June. The shoots of the same year are usually employed, as they more readily emit roots, and assume a free growth. The outward and most robust shoots should be chosen, and cut from five to seven inches in length. All but the top leaves being removed, insert by the dibble almost down to these, in rows six inches apart each way, in a shady border, and during moist weather, otherwise water must be given immediately, and repeated occasionally, until they have taken root. When the plants thus raised have an appearance of spindling, or run up to flower, they are to be topped to induce laterals. In the au- tumn, if they have attained a tolerably shrubby growth, otherwise not until the succeeding spring, remove to their final stations; being taken up with as little injury as possible to the roots, and planted, if in a bed in rows two feet apart each way.
When there are rooted slips, they may be taken off separately, With their fibrous roots still pertaining, or the whole plant may be taken up and divided into as many separate slips as can be furnished with roots. These may be planted both in spring and autumn, but the first season is to be preferred. Set out at once where they are to remain.
By Seed is the most preferable mode, the plants affording finer flavoured, larger and greater abundance of leaves, than those raised by other modes. Sow in April, in a bed of rich light earth, in drills half an inch deep, and six inches apart. The plants soon make their appearance, and when two or three inches high, thin to half a foot apart, and those removed prick out at a similar distance. In the autumn or succeeding spring, as the plants are strong or weak, remove them to their final stations.
During their future existence, keep constantly clear of weeds. The decayed flower-stalks, stunted branches, etc, remove in early winter and spring, and the soil of the beds slightly turn over. All irregular growth may be corrected during the spring and summer. When the plants have continued two or three years, a little dry, well putrefied dung may be turned in during early spring with considerable advantage. A due attention to the mode of gathering has no small influence in keeping the plants healthy and vigorous. The tops ought never to be cropped too close, so as to render the branches naked or stumpy. This should be especially attended to in autumn and winter. During this last season, they are less liable to be injured by severe frost, if kept with a full regular head. If appearance is considered, fresh plants must be raised every three or four years. For drying, the shoots and leaves may be gathered any time in summer before the plants flower, which they do in July.
Two or three of the finest plants of two years' growth must be left, not nearer to each other than four feet, and when the plants begin to flower, a plentiful watering given, and repeated every other day until the seed has attained its full growth. When perfectly ripe, the plants being pulled up, and completely dried, they easily shed their seed if struck on the floor.
 
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