This section is from the book "The Gardener V2", 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.
To have Mignonette in flower all through the winter adds greatly to the charms of the cut-flower basket; and when in handsome plants, intermixed among other things in the conservatory, sending out their fragrance, it forms a feature which is enjoyed by all. To have the plants in bloom by the month of November, the seed should be sown about the end of March. We use both pots and seed-pans. If sown in pans, the strongest plants can be selected, but we find little difference between the two ways. If sown in pots, about the 3-inch size will be large enough to begin with, having them perfectly clean and well drained, with a little moss on the top of the crocks; sprinkling a little soot over all will be beneficial in keeping worms from getting into the pots. This should be done at all the shiftings into larger pots.
The soil should be rather free, and passed through a half-inch sieve. When sown in pots at first, they should be nearly filled, the soil gently pressed down, and a few seeds placed in the centre of each, covering them over with soil to about the thickness of the seed. Give a good watering, and place the pots near the glass in a temperature of 60°; if the surfaces of the pots are shaded until the plants make their appearance, so much the better, as I find the fewer waterings Mignonette gets at this stage the better; it thrives and grows stronger afterwards.
As soon as the plants are large enough to show which is the strong est, all the others are taken away, putting a small stick to the one left: to this it is tied as it grows, in order to keep it from breaking at the neck, which they are very liable to do. "When about 6 inches high it will require another shift into a 6-inch pot, observing the same care as before in regard to drainage: the soil should be only chopped with a little leaf-mould, a good sprinkling of sand and a little soot should be added, and the whole well mixed together.
We find 11-inch pots large enough for either trees or pyramids. If trees are wanted, the leading stem should not be stopped until it has reached the height required, and then the six top side-shoots will be found enough to make a fine head, if properly attended to in regard to pinching and tying down to a small trellis made of wire, the shape of an umbrella. In pinching out the side shoots a pair of Grape scissors will be found the best, as they do not injure the leaf attached to the stem, which must be taken great care of all through. By growing in a temperature of 60° near the glass, giving manure-water twice a-week after they have filled the pots with roots, with daily syringings overhead, they will by the month of November amply repay all the labour bestowed upon them. Other two sowings at intervals of a month between will keep up a supply of plants in flower until it can be had out of doors. The same treatment applies to pyramids, only none of the side-shoots must be pinched away.