This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
Tender bedding-plants, as Verbenas and Ageratums, do better propagated during the present month than those propagated earlier in the year. Accordingly, as many as possible of these and kindred subjects ought to be struck this month. A properly managed three or four light frame, set on a hotbed of dung and leaves, makes a capital place for propagating purposes at this season. A portion of the surface of the hotbed may be covered with a layer of light material and cuttings dibbled into it as soon as the heat is at a safe point. When the cuttings are sufficiently rooted they are boxed off, a little fresh material added to the surface of the bed, and another batch of cuttings introduced. I always obtain my best plants propagated thus. The greater number of the Dahlias required should also be propagated this month, as these can be grown on to strong plants without in any way being drawn or becoming pot-bound. Seeds of quick-growing plants, as the Castor-oil family and variegated Maize, should now be sown. Where there is a chance of their not getting proper treatment through overcrowding, the sowing may be deferred still later. Should seed of the "Golden Feather" Pyrethrum be not already sown, no time should now be lost in doing so.
I merely sow it thinly in boxes, and when large enough prick out the seedlings directly into their summer quarters. Tagetes signata pumila, ten week Stocks, Asters, Marigolds, and Phlox Drummondii do well sown now in cold pits or frames, transplanting the seedlings when large enough from thence into their permanent places. The following hardy annuals, sown this montb, will come into flower throughout the summer, and be very showy till late in autumn. A hundred per cent more seeds need not be sown than plants required; and, when large enough to thin, give each plant as much space as other bedding-plants. Delphiniun-cardiopetalum; Limnanthus Douglasii; Linum grandiflorum rub-rum; Lupinus Cruickshankii; Lupinus nanus albus; Nemophila insignis; Gilia tricolor; Koniga maritima; Leptosiphon densiflorum albus; Specularia speculum; Viscaria oculata. These are all good. All hardy or nearly hardy subjects should be got into their places without delay. Owing to the severe winter, work in most departments will be still in a backward state, but no time should now be lost in getting all kinds of hardy plants divided and replanted. Violas, if not already planted out, should be immediately taken in hand.
These require most liberal treatment, and a dressing of cow-dung should be dug into the spaces these are to occupy. Calceolarias may also be planted now. Of course these will have been growing in the open for some time back. Where they have been coddled in frames with lights over them, they will require care after being planted out, as a sharp frost under these conditions would tell severely. And just a word as to "hardening off" tender bedding-plants. Where these have been grown in a moist, close atmosphere, it sometimes happens that when turned out to be "hardened off" they are positively withered up with the change, and the summer is far spent before the plants get over the effects of this treatment. It were much better to mat up hardening frames for several days, and, if possible, uncover in showery weather, than to have their life juices abstracted under the too sudden change. Plants grown under an airy regime do not suffer from such changes with ordinary care; but very many bedding-plants are not grown under such a condition. Old stock of Phloxes and Delphiniums, which will be now producing a too numerous array of shoots, should have the most of these taken off, leaving from three to six of the strongest to flower.
Tritomas should be divided at this season; moderate-sized clumps make far better decorative subjects than those which have occupied the same positions for a great number of years. Alterations in the shape of beds, or other work requiring removal of turf, should be finished without delay. Such work may still be done with safety, provided a small breadth of turf is lifted at one time and relaid without delay. Edgings of walks should be trimmed as soon as the grass has been mown the first time for the season. The walks should be diligently hoed at this time, as by so doing much hoeing will be prevented during the summer season.
R. P. Brotherston.
In this department do not get on faster than is really necessary. It is quite general to find Geraniums potted up before sufficient heat can be given them to root rapidly, while cuttings of Verbenas and other tender bedders are struck, and placed in odd corners indoors and out of doors, without progress being made in anything - the plants meanwhile getting into a wiry condition, which it takes many precious weeks of summer weather to get them out of again. Prepare the plants by generous treatment to make strong cuttings and plenty of them, but wait till the cuttings can be rooted quickly, and turn them out as soon as possible into beds in cold frames. In the middle of March plant out Violas, and also transplant any hardy bedders into their positions in beds and borders. Leave hardy herbaceous plants till the same time. Echeveria secunda glauca should be kept as cool as possible, merely protecting from frosts. Draceenas in a small state keep growing, and make the most of seedlings of Acacia lophantha.