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.
Very likely it is as you suppose, that your ground is too damp and cold for Alternantheras. They thrive best in a rather elevated situation, in light rich soil, and under such conditions they do not easily suffer from watering or rain. They should do well enough in your locality, and we would advise you to give them another trial, preparing the beds with light rich soil, and slightly raised above the ground-level. They are very beautiful where they do well, and Amabilis and Magnifica are probably the best worth growing. The plant you enclose is Tradescantia discolor. It may do on a rockwork outdoors for a short time in summer, though it will never be so beautiful as under glass.
Sow the Kales about the end of April in poor soil." Prick them out thinly in beds - in poor soil - when fit to handle. Before transplanting them in autumn cut round each plant with a small spade or trowel, and in a fortnight after remove them, with balls, to the beds.