FLOWER GARDEN

Evening Post, Volume CXXIII, Issue 54, 5 March 1937, Page 4

FLOWER GARDEN

HYDRANGEA CULTURE

VALUABLE HINTS

COLOUR TREATMENT

Some valuable hints on the growing of hydrangeas were given by Mr. R. E. Martin in an address at a meeting of the Karori Horticultural Society. In view of the fact that in current gar-

dening literature very little appears

about the culture of this increasingly popular flower, Mr. Martin's advice on the subject should be of great benefit to horticulturists. In submitting his hints, Mr. Martin said he hoped-that they would be criticised, amended,, and added to so: that eventually the society might be.able to publish a first edition on the-subject. "Almost any soil will grow good hydrangeas if reasonable care and attention are given," stated Mr. Martin. "Very light soil is certainly difficult on account of its poor retentive quality, but the addition of humus and particularly organic manure helps. Raw clay after a few years of cultivation can. be a suitable "base soil if well drained* sanded, and loosened by the addition- of coarse hedge clippings, straw, etc. The idea is a good strong loam, not too heavy to stand the addition of generous quantities of cow manure without becoming 'livery.' In preparing a bed for planting, it is worth while going to considerable trouble to assure a soil that will not cake unduly. Remember that when the plants become established deep cultivation will not be possible on account of the surface roots. These must on

no account be damaged, and if heavy

top dressings are considered necessary it is advisable to add one or two inches of soil. A vigorous bush will

appreciate this every second year.

"Concerning colour and colour treatment, in my opinion, the average grower would be better advised to plant a good selection of proved varieties, cultivate them carefully, and let colour take care of itself, rather than strive after colours that can only be induced by elaborate preparations and continual after treatment. Broadly, the rule covering colour appears to be: A svveet soil tends to produce pink blooms; a sour or acid soil is necessary' for blues. Lime is the principal sweetening agent, and is best applied in-the form of either crushed ■ oyster shell or carbonate of lime (crushed limestone). ■ Over-liming, particularly with other more caustic forms of lime, causes a disease known as lehlorosis, easily recognisable by a whitening of the leaves. Treatment, neutralise by applying sulphate of iron or alum. Use only organic manure on soil you wish to keep sweet. Most chemical fertilisers tend to sourness, and for other reasons are not to be recommended. Sulphate of iron and alum are both suitable for souring the soil, and both or either can be incorporated with the soil or applied in liquid form. Alum must be used sparingly,' or it will burn Ihe roots or leaves, and if used in liquid form should.be preceded, by a good watering of. the soil to be treated.

"A selection of a dozen varieties can be made for either soil that will produce a wide ra.nge of shades, and all of- them will be,beautiful if given-.the. right site,-..ample food, and particularly plenty of water after the buds are formed. To those who are determined to grow the colour that won't come naturally in their soil, I can only tell something of my own experiences, and advance my theories for consideration. In common with most Karori soil, mine is sour, inclined to granulate, and of medium quality. There is higher ground of a similar nature on three sides of my garden. I have used cow and fowl manure, the first liberally, and carbonate of lime, in proportion of five pounds to the square yard, on some of my beds. Other beds have been treated only with decayed garden refuse, and large quantities of iron and steel lathe turnings from an engineer's workshop. It all seemed so simple. The first treatment was to produce pink blooms, the second blue. But it is not quite so simple as that; I had not taken into account the higher ground and consequent seepage. The- blues are all right, and my treat- . xnent has intensified them, but the pinks are proving difficult to manage. .In*one triangular bed, containing about twenty bushes, I have every shade from deep blue to bright pink, sometimes even -on the same plant, some blooms tjjSng blue one half and pink Wig other. The whole of that bed has iegjt heavily enriched with cow nJSnjurc, with annual top dressings of 06M manure* The reason for blue colour Is ■■■me seepage of sour water tfnryn fjgie higher ground surrounding thfTbed. Last autumn 1 planted a hundred, tip cuftings in my glass-house to flower this summer. Half of them •were treated for pink and half were struck in soil taken from the beds Msuch produce-blue flowers. Every bloom vras pink! '?^, confess I am more than . mildly Huzzlei to iaccqunt for such a result N?xt,'month I will be planting a new Im; of cuttings, and as soon as they are,,well rioted my colour treatment lojJMalues will commence. I propose to use^sulphate of iron, alum, and dilute sulphuric acid in various quantities about once every three weeks. Some plants will be treated alternately with all three, some with one only of these souring agents, and some with two only in turn." I hope to have something definite to report next year as a resiiilt of my experiments. "To grow separate colours in the garden, I suggest beds raised .above the level of seepage water, and the whole of each, bed treated for either pinks or blues. There will be an interesting range of shades in each^bed, as individual varieties have their own tendency to intensity or delicacy of colour. I am growing about 45 varieties, and can show, most of them in both blue and pink shades, so I think it can be stated definitely that there is nothing approaching a fixed colour in any > -hydrangea, although some varieties certainly show strong tendency to pink or blue in neutral soil. PRUNING AND SITUATION. "I would say that anyone who can prune a rose bush can : prune a hydrangea. The rules are very similar. First one should cut out all weak growth and any old wood that has lost its vitality. Where bushes- are grown close together (they should not be closer than four feet apart each way) it is advisable to keep the centres open to admit sufficient sun and air to ripen the wood. I also recommend cutting out each year a number of old leaders to promote fresh growth from ground level. In this way, providing the bushes are well fed, they-should give good blooms for many years. Usually I prune to about .the third pair of buds, and if the leaders are close together rub off one bud, the other forming a good long stalk to carry the bloom. Every leader should, of course, be stopped. In very favoured localities pruning may be done the last week in July, but where there is any danger, of late frosts, the third week in August is not too late.

"To grow beautiful hydrangeas situation is of great importance. The name derives from hydor, water, and aggeion, a vessel, referring to the cup form of the capsule or seed vessel, but

the whole plant must be considered as a veritable sponge, particularly from the time the flower buds commence to form. During this period of very rapid growth, the stems, leaves, and bracts absorb very large quantities of water, and the whole growth is lush and soft. Wind damages the blooms at any stage of their growth, and if shelter from wind- can be given a good start will have been made. If exposed to the afternoon sun, evaporation is faster than absorption, and the whole plant may wilt leaving the coloured bracts particularly susceptible to bleaching and discoloration. For this reason I recommend planting either under the partial shade of trees, which admit intermittent sun to penetrate, or where some buildings, hedges, or other high shelter exclude all sun between say II a.m. and 4.30 p.m. Undoubtedly the canopy tree situation is the best from every point of view.

"I know of no plant so easy to propagate from cuttings. Almost . any partly-ripended wood will root. Some varieties show a marked tendency to break to side shoots, and these taken with a spur root grow very readily, but in my experience take longer to produce flowers than either tip or lower stalk cuttings. From preference I take my cuttings from old bushes rather than young ones, as I believe they mature sooner. PRESERVING BLOOMS. "A bloom should not be picked before it is ripe, particularly in hot weather. A rough guide is the development of the bracts. In most varieties when these are all fully coloured the bloom is ready for picking. The stalk should be split for about two inches, and, if not picked in the early morning, the stalks should be plunged in water right up to the top leaves for several hours. Alum appears to be the most satisfactory preserving agent, and should be added to the water in the proportion of a saltspoonful to one gallon—no stronger, or the blooms may be ruined. Some people recommend dipping the ends of the stalks in boiling water for a few minutes immediately after picking, but I have not noticed that this is any great assistance."