Dahlia Cultivation—Part Two (1853)

This article is adapted from the book The Dahlia: Its History and Cultivation, with Description of All the Best Show Flowers by Robert Hogg. It was published in 1853 by Groombridge and Sons, London. 

Although the original work is in the public domain, this article has been edited for the modern reader and contains new material. 

This version is Copyright © 2024 by Steve K. Lloyd and may not be reproduced without permission.

Robert Hogg was born April 20, 1818 in the Scottish border town of Duns, in the historic county of Berwickshire. He was schooled in law at Edinburgh University and earned an LLD (Legum Doctor) but no records were found to indicate that he ever pursued a career in that field.

Instead, in 1842 he joined the Brompton Park Nursery at the age of 24. He worked there for just seven years, leaving in 1849 to contribute to and edit horticultural works such as "Cottage Gardener", "Journal of Horticulture", and "Florist and Pomologist".

Hogg's professional interests appear to have focused on the study of fruit-bearing plants. He had published a 74-page booklet titled "Manual of Fruits" in about 1847, and in 1851 published a volume on apples which was projected to be the first of a multi-volume work titled "British Pomology". It received favorable attention, and was republished in 1859 as "The Apple and Its Varieties".

Dahlia Cultivation—Part 2 by Robert Hogg (1853)

Edited with revisions by Steve K. Lloyd © 2024

4. — Thinning the Branches and Flower Buds. There are several varieties of the Dahlia that produce great numbers of shoots or branches, and such plants require, in order to produce fine large blooms, a considerable number of these branches thinned out; but this must not be done at once. 

Whenever the plant seems inclined to produce such a number of small side shoots, as would evidently, if allowed to remain, make a dense bush, then reduce them by thinning. But do this gradually. It is impossible to give a definite rule for this operation. The grower must have his eyes open, and exercise his judgment in thinning the shoots. 

Some varieties grow naturally few shoots; for instance, Turner's Miss Vyse, and Mitchell's Mrs. Shelley. On the other hand, Trenfield's Admiral Stopford, Keynes' Lady of the Lake, and Old Springfield Rival produce an abundance of small branches, which must be well thinned out as the plants grow. 

In general, it may be remarked that such varieties as naturally produce large coarse flowers, may be allowed to have more branches. But such dahlias as have small flowers should be thinned freely to throw the strength of the plant into the shoots that are left, to enable them to bring forth larger blooms. In thinning the shoots do not break them off, but remove each with a sharp knife, cutting them off close to the stem.

The blossom buds should also be thinned or rubbed off. Some kinds produce such clusters of buds on the ends of the shoots, that, if they are all allowed to bloom, there actually would not be room for them to expand, much less to bring out good flowers. All such should be disbudded severely almost as soon as the buds are visible. This must be done with great judgment and care. One bud to each small branch will be quite sufficient for such free bloomers.

5. — Protection from Insects. The insects or vermin that prey upon the Dahlia are the snail or, as it is commonly called, the slug, of which there are several varieties, all equally destructive. The time when this pest does the most mischief is when the plants are first set out.

A good preventive is a circular pan, with a hole through the center, so large as to allow for the stem to swell to its utmost probable size. It forms a circular basin, which should be kept full of water to prevent the slugs from reaching the plant. For very choice or new varieties such an implement may be used, and if taken due care of will last for many years. 

For large collections perhaps it would be too expensive to apply to each and every one. Then it becomes necessary to use other means, such as sprinkling quick lime frequently around the plants, and diligently, every morning, searching for the slugs and destroying them.

The next is the earwig, a more destructive enemy still, for it preys upon the flower itself just at a time when it is in perfection, and ready for exhibition. For this plague, traps must be set early before the flower buds appear. The very best trap is a small empty garden pot, with a little hay or dry moss in it, turned upside-down, and placed on the top of each stake. These must be examined every morning early, and the insects shaken into a vessel of hot water. As this insect feeds during the night, it is a good plan to look for it with a lantern during that season, catching him at his work of mischief, and destroying him. Also set traps of dried bean-stalks, cut across between the joints. Into these he will retreat as soon as daylight appears. Blow him out at one end into the hot water, which will quickly finish him. All these means must be diligently followed till all the earwigs are destroyed.

The green fly in warm dry summers sometimes attacks the young shoots of the Dahlia, and causes them to curl up by sucking their juices. These are easily destroyed by a syringing [spray; ~Ed.] or two of tobacco water.

The thrip is a very destructive insect to the blooms. When it abounds it sucks out the color, leaving them spotted, and completely spoils them for exhibition. It prevails most in long continued dry weather. Unfortunately there is no application that will destroy it but will also destroy the bloom, except that of tobacco-smoke, and that is difficult and expensive to apply effectually, requiring a kind of tent made smoke-tight. 

As dry weather is favorable to their increase, so wet weather is a great preventive against their ravages. Therefore the syringe must be called into requisition, and used freely during dry weather every evening. This not only prevents the increase of the thrips, but also the red spider and the green fly. It also freshens the plants, and cleanses the leaves from dust and dirt — points of culture always desirable to be attended to.

Therefore syringe freely at the close of every dry day, and the good effects will soon be visible in the superior health of the plants, and the size and clean appearance of the bloom. In syringing, care should be taken not to force the water too strongly upon the blooms, or it would injure them as much as the insects would. 

It is advisable then to use the syringe in an early stage of growth, before the blooms are open. As the syringing will knock down to the ground considerable numbers of insects, these might be destroyed by raking the ground over immediately after the syringing. The insects then are mixed and daubed with the soil, and effectually destroyed. This raking need not be done more than once a week. 

Another mode of checking the ravages of this pest is to take a pair of bellows, and blow the blooms strongly with it. The thrips is a jumping insect, and when the wind from the bellows is blown upon it, it will jump away on the ground. If this is done just before the syringe is used, and the ground raked, a still greater number will be destroyed. The zealous amateur, who is anxious and determined to stand first at the exhibition, will not begrudge all this pains and trouble in order to ensure success.

6. — Staking.Besides the center stake, which has been already mentioned, it will be advisable to place three or more around large, spreading plants to secure them from being broken with the winds. These are apt to prevail during the autumnal months, when the flowers are in their greatest beauty.

To these side stakes, securely tie the side branches, but be careful the string does not bind the branch too tightly, or the remedy would be as bad as the disease. Yet they must be securely tied, to prevent the branches being broken, or the flowers dashed against each other, or the foliage. This point must not be neglected, or the consequences, should a strong wind arise and find the shoots not tied, would be very destructive both to the plants and blooms. 

In tying the branches to the side stakes, spread them out as much as possible to allow the air to play freely amongst them.