Adiantums

ADIANTUMS, the most popular l of all pot-grown ferns, are com­monly called maidenhair ferns be­cause their fine, shiny, often black leafstalks resemble human hair. They have fast-spreading rhizomes that grow horizontally just below the sur­face of the potting mixture. The fronds are 8-15 inches long and divided into many pinnae. Mature plants pro­duce brown clusters of spore cases on the undersides of the pinnae. 

RECOMMENDED ADIANTUMS A. capillus-veneris, commonly called Venus-hair, rarely grows taller than 12 inches in a pot. It has roughly triangular light green fronds compris­ing many delicate-looking, fan-shaped pinnae. In particularly fine specimens the fronds may be up to 24 inches long and 10 inches wide, with individual pinnae an inch across. A. hispidulum (Australian maiden­hair) seldom grows more than 12 inches tall. Its fronds—usually 9-12 inches long and 6 inches wide—are roughly divided into several spreading sections much like the fingers of a hand. The almost oblong, leathery pinnae are reddish brown when young, turning medium green later. A. raddianum (delta maidenhair), also known as A. cuneatum, grows up to 18 inches tall with a spread of up to 24 inches. The triangular, dark green fronds may be 8 inches long and 6 inches at their widest point and are divided into numerous delicate, wedge-shaped pinnae. There are many forms, all slightly different in scale, color, and general shape. The fronds of all forms, however, are semi-erect at first, drooping gracefully as they mature. One form, A.r. 'Frag-rantissimum,' has denser foliage with a pronounced fragrance. Another, A.r. 'Fritz-Luthii,' is easy to grow and has longer fronds than the type plant. A. tenerum (brittle or fan maidenhair) grows up to 3 feet tall. Its triangular, pale green fronds are divided into many fan-shaped pinnae that may be deeply cut at the edges. There are several forms, some with rose-tinted fronds. A.t. 'Farleyense' (glory fern) has drooping fronds with deeply cut, frilly-edged pinnae; the fronds of A.t. Wrightii' are pink when young but turn fresh green, and their fan-shaped pinnae sometimes overlap each other.

PROPER CARE

Light Provide bright light, but do not subject these ferns to direct sunlight. Temperature Adiantums will grow well in any normal room temperature and can tolerate temperatures down to 50°F. If the temperature rises above 75°, stand pots on trays of moist pebbles, and mist-spray daily to pro­vide much-needed humidity. Watering These ferns should be kept only slightly moist at the roots. The commonest cause of failure is to per­mit the root ball to dry out and then to soak the plant. Aim at a medium course by watering moderately— enough to make the mixture moist throughout but letting the top inch dry out between waterings. Feeding Ferns, though not greedy, benefit from occasional feedings of standard liquid fertilizer during their active growth period. Recommended frequency of feedings depends on the type of potting mixture. Potting and repotting The potting mixture for adiantums must be cap­able of* holding water and yet of providing good drainage. A peat-based mixture is suitable, but only if the plant gets some fertilizer at least once every two weeks.

Feeding is much less important— fertilizer will do once a month—if equal parts of soil-based potting mix­ture  and coarse leaf mold or coarse peat moss are used. Repot adiantums only when dark-colored roots appear on the surface of the mixture. The best time for re­potting is early spring. Instead of being repotted, an older plant may have some outer roots carefully re­moved before being replaced in the same pot with the additisn of fresh potting mixture.

Propagation New plants will grow from small sections of the rhizome with one or two fronds attached. Break off such sections whenever adiantums are being repotted. Alter­natively, separate older plants into a number of clumps. Pot each growing section singly (or put several in a pan or hanging basket) in one of the recommended potting mixtures. Water new plants with extreme care, following watering instructions for mature plants; overwatering may well result in rotting.