=Dicksonia.= _Filices._ Division mostly. See Ferns. =Diclytra.= See Dicentra. =Dictamnus= (Dittany, or Fraxinella). _Rutaceæ._ Seeds should be sown as soon as ripe. Division is used. =Dictyosperma.= See Areca. =Dicyrta.= See Achimenes. =Didymocarpus.= _Gesneraceæ._ Cuttings, which are obtained from young shoots when commencing growth, and placed in sandy soil, in heat. Also by seeds. =Didymosperma.= See Areca. =Dieffenbachia.= See Caladium. =Diervilla=, Weigela. _Caprifoliaceæ._ Suckers. Cuttings may be made in spring, summer or autumn. Hardened green cuttings, handled under a frame in summer, are extensively used by nurserymen. (See page 58.) They are sometimes grown from cuttings in winter from forced plants. Hard-wood cuttings, made in winter and planted in spring like the grape, succeed well. =Digitalis= (Foxglove). _Scrophularineæ._ Seeds, sown in spring, either in-doors or in the open. The common foxglove (_D. purpurea_) often self-sows itself. =Dill= (_Arethum graveolens_). _Umbelliferæ._ Seeds, in early spring. =Dillenia=, including Colbertia. _Dilleniaceæ._ Seeds, which, however, are grown with much difficulty. Cuttings of half-ripened wood may be placed in sand, under a frame, in bottom heat. =Dimorphotheca.= _Compositæ._ The seeds of the annual sorts should be sown in heat in spring. The perennials are grown from green cuttings. =Dionæa.= _Droseraceæ._ Propagated sometimes by seed; usually by dividing the plants. =Dion=, Platyzamia. _Cycadaceæ._ Propagated by seed. =Dioscorea= (Yam). _Dioscoreaceæ._ The tubers may be divided in autumn or spring, when not growing. Seeds are sometimes used, so are the tubers which form in the axils by the leaves. Stove species can be propagated by cuttings of the half-ripened wood. =Diosma.= _Rutaceæ._ Cuttings in sandy peat, and under a frame placed in very gentle heat, will soon root. =Diospyros= (Date Plum, Persimmon). _Ebenaceæ._ Seeds are used for the hardy species. Also by cuttings of half-ripened shoots. Those requiring stove heat strike best from ripened shoots, placed in sand in a brisk bottom heat during spring. See also Persimmon. =Dipcadi=, Uropetalum. _Liliaceæ._ Increased by offsets in spring. =Diplacus.= See Mimulus. =Dipladenia.= _Apocynaceæ._ In spring, when the plants commence new growth, cuttings from the young shoots are made. These, or single eyes, should be placed in a mixture of sand and peat, in good bottom heat. =Diplazium.= See Ferns. =Diplothemium.= _Palmæ._ Propagation is affected by seeds. =Dipteracanthus.= See Ruellia. =Dirca.= _Thymelæaceæ._ Increased by seeds or layers. =Disa.= _Orchideæ._