Could you suggest a true lemon suitable for home gardens?
Yen Ben is a good choice. It's also the foremost commercial variety grown in New Zealand, a Lisbon-type lemon but smaller growing, with thin-skinned fruit that has few seeds. The lemons have a sharp, classic flavour, with the main cropproduced in autumn and winter, plus a few fruit throughout the year. Yen Ben is one of the hardier lemons, best planted in a sunny, free-draining spot protected from strong wind and hard frosts.
My fine-leaf maidenhair is not doing well indoors - can I plant it outside?
Possibly, but it may die down in frosts so be prepared to cut back dead foliage in spring to encourage new growth. You could divide the fern and risk only half outside. Choose a moist shady position with rich soil, but be aware the finer-leaved varieties are fussier than other maidenhairs. Note: New Zealand has several native species of maidenhair, which could make a hardier choice inside or out.