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.
It will be some time hence when the bedding Lobelias will be dis-carded from the flower-garden. Their dwarf growth, and their ability to stand severe drought and a hot burning sun, combined with their free and continuous blooming properties, make them so useful that, were they abandoned, but little could be found so well adapted to take their place. I am so much an admirer of the Lobelia as a bedding plant, that I have made a trial of several of the leading varieties with a view of ascertaining which of them are best adapted for bedding purposes, and I now proceed to notice the several kinds subjected to such trial.
Of pure white Lobelias, I have met with but two really of this colour. I may state that I have seen two or three termed L. speciosa alba, but neither pure white, as the flowers have invariably come slightly edged or tinted with blue. Of the two white varieties referred to, one, named Miss Murphy, belonging to the pumila or dwarf-tufted section, I have entirely discarded, as being altogether worthless for outdoor purposes. Used as an edging in a cool conservatory, it may prove useful; but I have always failed to make it of any service in the flower-garden, except to denote its claim to be on the list of "plants to avoid." My second white - viz., Queen of Whites - is much superior, though by no means perfect as a white-flowering bedding Lobelia. It has the L. speciosa habit of growth, hardihood, and general good qualities, but the flowers, though plentifully enough produced, are small in size, which detracts from its effectiveness. It is, however, the best pure white bedding Lobelia we have, and I mean to use it till a better one takes its place.
Lobelias with lilac or pink flowers are now becoming somewhat plentiful, and give us new and attractive colours in this useful class of bedding plants. One of the very best is Rosy Moon, which produces rosy-pink flowers having a small white centre, as large as those of the ordinary type of L. speciosa, and a capital habit. Rosy Gem is similar in character, but has the addition of some purplish crimson spots on the upper part of the flower, and, though attractive, is to my mind scarcely so good a bedder as the first named. The pumila section gives us many more varieties, and, as a general rule, they have better constitutions, and can stand exposure better, than the white Miss Murphy. Of these the best are Beauty of Ravensbourne, pinkish lilac, bright and effective - a capital edging-plant; Distinction, rosy red, with large white centre, very pretty and good; and Fairy, having pretty pale pinkish-white flowers, spotted with lilac. For culture in pots for house decoration, this is well worthy attention.
Then there are dark and light blue Lobelias, and also some that may be termed edged flowers, of which L. erinus Paxtoniana is a very good type. Of the dark-blue flowers the best are L. speciosa var. Drummondii, rich deep blue, a fine and effective hue of colour, compact in growth, very free, and stands well; Trentham Blue, with large deep blue flowers, a fine and showy bedding kind; Blue Bonnet, dark blue; Painter, rich deep blue, mottled with white, a thoroughly good and effective variety, novel and distinct; and Blue King, a deep shade of bright blue, dwarf in growth, very free and good. Of light-blue flowers, the best belong to some dwarf-growing compact kinds - such as Blue Tom Thumb, lively pale blue, with white centre, habit very dwarf and compact, a free and continuous bloomer; Lee's dwarf Blue, azure blue, with small white centre, habit very dwarf and dense, and a thoroughly free-blooming variety; and Pumila elegans, deep azure blue, with very small white centre, very free and good - a capital edging plant.
The best of the edged flowers I have found to be Little Gem, the flowers white, broadly edged with blue, habit dwarf and compact - an excellent bedder; and Serena, white, with very slight edging of blue.
There are many others; but of these I can speak with confidence, having tried them. I have not seen Tyninghame Blue, but from its published description I should take it to be a good thing.
I saw not long since what I thought a capital mode of propagating Lobelias. I was visiting a gentleman in my neighbourhood, and saw on a shelf in his greenhouse a number of Lobelias in 60-pots, that had made growth which hung down round the pots, and young rootlets were starting from the -base of each shoot, owing, no doubt, to the prevailing moisture. I was informed that pieces of young growth are plucked from the Lobelias in August and September, placed singly in 60-pots, and put on the shelf of the greenhouse; here they remain all the winter, and become dense masses, which throw out roots as described. In the spring the plants are pulled to pieces; and as each shoot has rootlets attaching to it, a large number of plants is obtained from the division of one of them. This process certainly saves the trouble of striking cuttings; also the somewhat uncertain task of successfully wintering old plants for stock purposes.