Hydrangea Hortensis .sx ( See Coloured Plate .sx ) A CULTURAL GUIDE .sx For Pots of Tubs .sx THE hydrangea has been cultivated as an indoor plant for a great number of years , and is mentioned by Mawe and Abercrombie in their " Dictionary of Gardening , " 1797 , as " a plant worthy of a place in every stove , producing bunches of flowers of a whitish-green colour as first coming out , but , when full blown , turning to a pale reddish-white .sx " What these old gardeners would have thought of our modern beautiful varieties of this flower cannot be imagined .sx The past decade has seen the hydrangea raised to the front rank as a subject for indoor cultivation , and it has other values , for it is one of the best pot flowering plants for the dwelling room , and is very suitable for furnishing large vases and tubs that are stood on terraces , at doorways under verandas , etc. .sx Hydrangeas are Easily Propagated .sx From cuttings , the usual plan being to root suitable shoots in the spring , and , when they have developed a sufficiency of roots , to transfer them singly to 3in .sx pots , using a compost consisting of rich loam , leafmould , and sufficient sand to render the soil porous .sx These plants should be grown on , and , when ready , shifted into 5in .sx pots , in which they will flower the following season .sx During their first season of active growth every effort should be made to get the wood well ripened by exposure to plenty of air and sun , taking care to see that the roots never suffer for want of water , and resorting to feeding occasionally to build up strong , healthy plants that will be sufficiently vigorous to develop big trusses of bloom , a foot or more across .sx Another method is to take the cuttings in the autumn - say , August or September - pot them singly , as in the case of geraniums , and winter them in a warm greenhouse , but not allowing them to push much growth .sx These dormant plants should be started in the spring , and , where sufficient have been raised , they may be brought on in batches to provide a succession of flowers .sx In their flowering season protection should be given the trusses against direct sun , which would quickly fade the rich colours .sx The plant has a strong habit , and will fill the pot with roots ; these and the big leaves assimilate a lot of moisture , calling for very great care in watering , the foliage flagging quickly through drought , and a check of this nature is soon reflected in the plant going off quickly .sx When in active growth , liquid stimulant should be given the roots on two or three occasions weekly .sx The Newer Hybrids .sx of Hydrangea hortensis include varieties of beautiful shades of rose , pink , carmine , salmon , and similar tones , as well as some charming blues .sx There are white sorts as well , and the old white Thomas Hogg was a favourite with our forebears as a conservatory and greenhouse plant .sx One of the most prized varieties , and one largely cultivated by growers for the pot plant trade , is Parsival , with clear carmine flowers , the latter being pleasingly serrated .sx The growth of this variety is compact , and the habit of flowering very free .sx The dark green foliage throws the richly-coloured inflorescence into strong relief .sx Madame Truffaut has deep rose-coloured flowers that form nicely-shaped trusses .sx Gertrude Glahn , the variety which forms the subject of this week's coloured plate , is of grand form , and in its natural colour the pink shade is rich , but not hard .sx The blue flower is of the same variety , after the special treatment frequently adopted by growers to obtain this remarkable transformation .sx A good light pink is found in Lancelot , which grows freely , and develops a fine crop of its medium-sized trusses .sx Etincelant is one of the best of the light crimson varieties , and is largely grown for market , being an early sort .sx Mdme .sx E. Chautard is a reliable forcer and a strong grower , giving richly-coloured rose flowers .sx One of the best of the white-flowered sorts is Madame E. Mouillire .sx Others of merit are :sx Yvonne Cayeux , dark pink ; Kriemhilde , salmon-rose ; America , deep pink ; Beauty of Dresden , salmon-pink ; La Marne , a late variety , with clear rose flowers ; and Mrs. Baardse , vivid salmon .sx Of the blue-flowered , True Blue and Blue Prince may be recommended , but some of the sorts already named are sent out by nurserymen with blue flowers , after having been specially treated .sx All those named are to be had at a reasonable price .sx As an indoor plant , Hydrangea paniculata and its form grandiflora are very pleasing , and a useful subject for the stage .sx The treatment is similar to that of the hortensis type .sx For Outdoors .sx Hydrangeas of the hardier kinds are very ornamental in tubs , vases , etc. , both in and out of flower , for the foliage of healthy plants is very imposing .sx The receptacle should be provided with ample drainage , as big plants require copious supplies of water in summer .sx Small specimens should not be put into an excessive amount of soil ; this commonly results in sourness at the roots , followed by weakened growth .sx Rather grow the plant on in a big pot , stand it in the vase or tub , and pack around with hay or straw , and finish with a layer of moss .sx After a season or two it can be planted permanently in the bigger receptacle .sx Some of the newer hybrids may be used as terrace plants , etc. , but they will not survive severe frost , and will need a certain amount of protection in winter and to be on the dry side to keep them as dormant as possible .sx These big plants will respond to liberal feeding , and may be given clear liquid manure , or a quickly soluble fertiliser may be stirred in the water-can and used once or twice weekly in the growing season .sx To keep the plants shapely it may be necessary to secure some of the shoots with raffia to a central stake , but this should be done so that the means used are not readily apparent .sx Blue tints are produced naturally where there is plenty of iron in the soil , and an old-time method of changing the colour was to mix iron filings with the soil .sx An efficient modern way is to water with dissolved alum once a week from spring till flowering .sx The dose is one tablespoonful in a gallon of water .sx G. F. T. .sx SEEDLING CYCLAMENS .sx Making a Start .sx RECENT queries concerning these plants point to an ever-increasing number of admirers , which , considering how beautiful they are for room decoration , is not to be wondered at .sx But it is rather disappointing to some when they are told that early August is the best time to sow seeds , for this is a long way off , and in any case sowings then cannot result in plants to bloom next winter .sx There is no need to become impatient .sx An immediate start may be made by purchasing seedlings from specialist firms .sx Moreover , when one buys these young plants , the best possible start is ensured , for it very often happens that , when seed is sown in August the conditions are not ideal , with the result that plants are not as strong as they should be in spring .sx If a start is made now , valuable time is saved , for there is no doubt whatever , if the plants are well grown this summer , that they will be in bloom during the winter .sx The best plan is to pot up the plants immediately on arrival in thumb pots , in a mixture of equal parts leaf-mould and fibrous loam , with sufficient sand to ensure free drainage .sx Avoid too hard potting , and place the pots on a shelf at the warmest end of the house .sx Early in June , or perhaps a little sooner , larger pots will be needed .sx The best place for the plants after this is a cold frame , on a cool ash bottom .sx F. C. T. .sx The Amateur's Greenhouse .sx WHITSUN WORK .sx And Other Tasks .sx THIS season of the year finds work pressing in every department of the garden , but it is more than ever a busy time in the greenhouse .sx All sorts of plants are growing very fast , and there is a great deal of potting waiting to be done .sx The first principle of all successful plant growing is that no plant shall ever suffer because of delayed potting .sx It will be necessary to consider carefully which batch of plants is most urgently in need of attention , and arrange to get this done first , following on with those not so forward .sx Repotting Plants .sx To find out if a plant needs repotting turn carefully out of its pot , and judge by the quantity of roots it has made .sx Never allow judgment to be made by the appearance of the foliage only , for often this is deceptive .sx The preparation of correct soils will be one of the first jobs , and these should always be got ready before the day of potting , because the ingredients always mix better if left a week or two , and then turned again .sx Gloxinias which were recently started from corms will be ready for their final shift , and the thirty-two size pot is usually the most accommodating .sx Prepare a peaty mixture , and make sure it is not too wet , then when ordinary pressure is given in potting , there will be no risk of the soil going down too hard .sx Really this remark of having soils in the right conditions has a great deal behind it , for a compost that is in the happy condition of being only just moist enough to cling together , and yet break on the slightest touch , is ideal .sx Another general rule to bear in mind is that all plants , after being newly potted , must be shielded from bright sunshine , and that moist atmospheric conditions must prevail till the roots enter the new soil .sx This applies especially to plants such as begonias , caladiums , and subjects with large leaves , because , if they are allowed to wilt and the sun gets directly on to them , " burning " takes place , which greatly disfigures the plant , and may even kill it .sx The sun at Whitsuntide is usually of this burning nature , hence the hint .sx Amongst soft-wooded plants we may mention , there are begonias , salvias , celosias , browallias , and petunias , which must be placed in their final pots now if they are to be a success .sx For all these an ordinary mixture that is not too fine and yet perfectly porous will be suitable .sx At this time of the year all such plants should be watered in soon after potting , or , at latest , the next morning , for it is obvious that the small ball of soil filled with roots , which is now in the centre of the larger pot , will rapidly become dry , and this may happen even though the new soil appears moist .sx Once that ball of soil and root becomes dry it is a very difficult job to get it wet again .sx Of Hard-wooded Plants .sx there are a few that may want putting into larger pots , but there should not be many , as the general potting of these ought to have been done earlier .sx If , however , this has not been done , let it be tackled during the holiday .sx Creepers in pots will need feeding now with a little artificial manure , and all strong growths tied either to stakes or trelliswork .sx Plumbago capensis is growing rampantly , and must be well fed , and the same applies to the bougainvillea .sx Soot water is a serviceable and beneficial stimulant for most plants .sx Do not , however , use it for syringing purposes in a general way .sx For stronger nourishment it is best to rely upon approved fertilisers .sx Do not be too eager to make haste by giving stronger doses than indicated in the manufacturers' directions for use .sx Campanula pyramidalis , one of the loveliest cool house flowers , is throwing up its spikes of blue , and must be fed generously and frequently if the best results are to be obtained .sx Annuals that were sown in January are coming into flower , and most of them will need a deal of staking and tying just now ; do not neglect this , or it will be too late , once the growths become twisted and curled .sx 4 .sx