PREPARATORY TREATMENT OF PLANTS FOR CROSS-BREEDING
THERE is no process of the gardener's art which is better understood by the amateur than that of crossing flowers. Yet, there is not another operation to which a gardener can turn his hand to, about which the great bulk of us gardeners know less of the essentials for success. If I had ten kinds of plants on my list for experiments in crossing next season which I never crossed before, I could hardly find ten men amongst all my acquaintances of whom I could ask advice about the ways I ought to go to work with them; and yet I venture to say, there are not ten men in the country who had ever crossed a flower who would not answer my question without the smallest hesitation. The mere act of crossing flowers is, indeed, the most simple practice in gardening, except pulling up a Groundsel, and then throwing it down where it grew. Simple as these two things are, however, the one of them is yet a problem to be proved, the other a very foolish act.
|*Reportedly a sport of Pelargonium Fothergillii or P. heterogamum|
Who can show me, or prove to himself, the right way to cross Mangles' Variegated Geranium*? Say, the best way, as if you were asking an editor. But I do not want to know the best way—perhaps the best way would not suit my conveniences for keeping and growing the plants; but if I knew the right way of growing the Geraniums for crossing, I would try to adopt it, although I might not be able to practise any but the second or third best way.
Talk about crossing being a simple thing, why to practise it intelligently is at this moment the most difficult question which practical science has to deal with. The work or process of putting a little dust on a given point, which is all that is done in crossing a flower, is simple, as they say; but the art by which the cross-breeder has to prepare his subjects for that very simple operation is just as difficult and as little known as anything under the sun.
The probability is, that every cross-breeder has an art of his own, which he never divulges for fear of being laughed at, or in order that no one else can run the race before him. I have an artful art in the preparation of all my breeders which no one knows but myself. But that is not here or there. The question is about the grand secret and how to get at it—how to prepare Mangles' Variegated Geranium, which is all but a botanical mule, and a barren plant in the hands of most people; but it has certainly seeded, and we had the account lately of its having been crossed by the pollen from the shorter stamens of the Golden Chain, by Mr. Smith of York; and the question now is, Did Mr. Smith induce this cross by some previous mode of management which was different from the usual run, or was it merely the effect of an accidental circumstance?
My own experience would lead me to believe there is no such thing as an accidental circumstance to cause a plant that is generally barren to bear seeds, whether it was crossed or not. Some plants are most difficult to cross or to hybridise, and temperature seems a main element in the success when they do unite with their fellows, as in cross-breeding, or with very different fellows, as in hybridising one species with another of a different cast and constitution. This is proved when they get plants to cross on the Continent which we cannot manage to cross or even seed here. Here, then, is the first proof before us of an element, or an elementary process, to induce a plant to cross or to bear seeds.
Then, the next question is this, Is temperature alone—that is, a higher temperature, the only means within our reach to cause certain plants to seed or cross, and is that temperature all that is necessary? Well, it certainly may be all that is required to get the plants to seed, but how about the seedlings? My opinion is, that there is a great deal more importance in the proper soil, and the kind of treatment the plant receives for the previous twelve months before crossing than in temperature. Then, if you could give that soil and that treatment to your plants for twelve months, or twice that number of months in a much better climate, so to describe it, than that of England, my belief is that your seedlings would exceed in value any that could be had in the unassisted climate of England under the best management.
We are all but unanimous that the higher temperature on the continent in summer favours the breeders there, as against our seedlings of the same kinds; and we may rest assured if that be so, that the fact does not stand alone. Other things, we do know, help our processes quite as much as temperature; and why not in this also?
The age and the condition of the mother parent at the time of crossing is, assuredly, of high consideration to the cross-breeder, and I think also to the hybridiser; but of him I am not quite so certain, as for some years past I have done very little at hybridising, although I first began crossing and continued at that branch of it alone for many years. But to this day I am all but at a loss as to the extent of the value of the condition of the male parent at that precise moment. I know to a certainty, however, that if I wanted to have an intermediate cross between a very strong mother—say Defiance Scarlet Geranium and by the pollen of such as Mangles' Variegated if it had pollen, I should need to prepare Defiance by reducing it through ill treatment to a mere scrub or skeleton during the previous season of growth, and to keep it down to that point during the winter and spring following up to the time of flowering for the cross, and the opposite treatment to be given to the weak male, say by taking a two-year-old plant of it in early spring, and with the best compost and treatment to keep it going all that summer without letting it open one bloom the whole season; to have it kindly seen to during that winter and next spring, and to take pollen from a particular truss at midsummer, and from particular flowers of that truss. I say I am quite sure these are safe steps to pursue with two such breeders.
Then I have some reason to suppose, although I have little experience to back me, that if the cross seeds were to be had from a weak parent, by the pollen of Defiance, which is very strong, that I should need to reduce Defiance just in the same way. What makes me name Defiance is, that of all the very strong Scarlets it is the most unwilling to seed by the pollen of the medium and the small in stature of its race. But keep it twelve months between starvation and death's door, and it will cross with most of them for an experiment; but it is too coarse in all its parts for profitable breeding. Such a plant as Mangles' Variegated Geranium I should suppose would need three seasons of the highest cultivation, with a minimum of stress upon its energy—that is to say, without allowing it to ramble about, as is its natural habit, or to produce one flower the whole time. Then if one undertook to cross it by the pollen of the Golden Chain, as has been done by Mr. Smith, I would have the Golden Chain invigorated just in the same way as Mangles', or the opposite way to that which would be necessary for Defiance for the same purpose. Both the father and mother in Mr. Smith's experiment appear to me to have not been quite up to the point of profitable breeding at the time he crossed them, and that was the real cause of the impossibility of rearing the seedlings, and not the fact of the pollen having been taken from the short stamens.
The prospect and possibility of a hundred trials of the same experiment being made next summer, induced me to write thus at the very beginning of the most busy season for crossing yet on record. Now and during the whole month of January is the right time to give the final potting to all the mothers of all the seedlings which will be worth looking at a second time by the Floral Committee—florists' flowers, bedders, and all hybrids, unless, indeed, the intended pollen parent is of very weak constitution. In that case I should not think it desirable to pot the much stronger mother sooner than the middle or end of April. Then it would have to be making new roots the whole time it was maturing the crosslings, to coin a significant term, and that of itself would be abundantly sufficient to balance the respective powers of both parents.
For all bedding plants which come from crossing, it is of the utmost importance that both parents be of the very same constitutional strength, or as near it as can be had—that both should have been under the highest cultivation the previous year with the above limitation—and that the mother is not wasting her strength in making fresh growth, or new roots, immediately before the crossing is effected and about that time; but from the time the seeds are sure of having "taken," as we say, or past the period at which that kind of plant would east its pods if they had not been fertilised, I never found that good or bad treatment was of much consequence to the seedlings. I know the very worst treatment of the parent is of no consequence to the seedlings of all Geraniums after they are fertilised twelve or fifteen days.
Although I never crossed for a florist's Pelargonium, nor ever read a word about the way they prepare them for matching, I am satisfied from my knowledge of other sections of the family that the Pelargonium is not much different from the Scarlets in this respect—that two-year-old plants make the best mothers— that the mother should not have been much stressed by free-flowering the previous season—that it ought to have all its roots made and finished, and the pot brimfull of them by the end of March or very early in April—that the first truss of bloom is not the best, to select flowers for crossing from—that a strong side branch is the best to bear the blooms for crossing—that no more than one truss be allowed to be on one such branch—that no dependance can be placed on the three blooms which generally open first, that is, those from each outside or shoulder of the truss and the very centre one, neither is there much to be expected from the last two or three flowers from the lower or bottom of the truss—that all such flowers are discarded by careful breeders—and lastly, that the plant is stopped carefully from the first day of crossing—also, that all the flowers to be crossed on one plant should be done as nearly at the same time as is practicable.
At all events the foregoing have been my grand secrets, and of the value of any one of them I have not the smallest doubt— they are all essential to good breeding.