Pernettya.--An American evergreen shrub, which, like all of its class,
thrives best in sandy peat; it delights in partial shade, and a moist
but well-drained position. It is increased by layers in September,
which should not be disturbed for a year. It is a good plan to mulch
the roots with leaf-mould or well-rotted manure. Height, 5 ft.
Petunias.--These ornamental half-hardy perennials prefer a mixture of
sandy loam and vegetable mould, but will grow in any rich, light
soil. Seeds sown in March or April, at a temperature of from 65 to 75
degrees, make fine bedding plants for a summer or autumn display.
As the seeds are very minute, they should be covered merely with a
dusting of the finest of soil. Moisture is best supplied by standing
the pots up to the rims in water. Pot off singly, harden off, and
plant out at the end of May. May also easily be raised from cuttings,
which will strike at any season in heat, but care must be taken that
they do not damp off. They flower in July and August. Height, 1-1/2
ft. to 2 ft.
Phacelia Campanularia.--A superb, rich blue, hardy annual. It will
grow in any soil, and is easily raised from seed sown in spring.
Flowers are borne in June. Height, 1-1/2 ft.
Phalaris.--P. Arundinacea is the well-known perennial Ribbon Grass;
it is easily grown from seed, and the root allows division. P.
Canariensis is the useful canary seed: it may be propagated from seed
on any soil. Height, 1-1/2 ft.
Philadelphus.--Among the best of our flowering shrubs, producing a
wealth of sweetly-scented flowers. For cultivation, _see_ "Syringa."
Philesia.--An American evergreen shrub which grows best in peat, but
will thrive in any light soil. It should occupy a cool position, but
be well sheltered from winds. It is increased by suckers. Flowers in
June. Height, 4 ft.
Phillyrea.--This effective border evergreen will grow in any ordinary
garden soil, and may be increased either by layers or cuttings. It has
dark green shining leaves, and is quite hardy. Height, 6 ft.
Phlomis (_Lion's Tail_).--This effective hardy perennial will grow in
any rich, light soil in a warm position, and is a fine lawn plant.
Flowers are produced from June to August. It may be increased by seed
or division. Protect the plant from damp in winter. Height, 3 ft.
Phlox.--For richness of colour and duration of bloom there are few
plants that can rival either the annual or perennial Phlox. The
trailing kinds are very suitable for small pots or rock-work, C.
Drummondi for beds, and the French perennials, P. Decussata, for mixed
borders. A rich, loamy soil suits them best, and they must never
lack moisture. They are easily raised in spring from seed, and the
perennials may be increased by cuttings placed under glass, or by
division. Flower in July. Height, 1 ft. to 2 ft.
Phormium Tenax.--A greenhouse herbaceous plant which succeeds best in
rich loam. It flowers in August, and may be propagated by dividing the
roots. Height, 3 ft.
Phygelius Capensis.--A greenhouse perennial bearing carmine and yellow
flowers in June, but is hardy enough to be grown on a warm border. It
is increased by off-sets from the root, taken off in May. Height, 2
ft.
Physalis (_Winter Cherry_).--A rich, light soil is most suitable for
the stove and greenhouse kinds, cuttings of which root freely under
glass. The hardy kinds will grow in any soil, and are increased by
seed. P. Francheti produces seed-pods over 2 in. in diameter, the
Cherry-like fruit of which is edible and makes a fine preserve. It is
larger than that of the old Winter Cherry, P. Alkekengi. They flower
in August. Height, 1 ft. to 2 ft.
Physianthus Albens.--This evergreen climber is a good plant for
training to the rafters of a greenhouse. It grows well in a mixture
of sandy loam and peat, and should receive bold treatment. Its white
flowers are produced in July. The plant is propagated by seeds, also
by cuttings. Height, 20 ft.
Physostegia.--Ornamental hardy herbaceous plants, ranging in colour
from white to purple. They like a rich soil, and can be raised from
seed sown in March. They also bear division. July and August are their
flowering months. Height, from 1 ft. to 5 ft.
Phyteuma Hallierii.--A very pretty hardy perennial. It will thrive in
any soil, blooms from May to August, and can be readily increased by
seed or division. Height, 1-1/2 ft.
Phytolacca Decandra (_Virginian Poke_).--A very fine herbaceous plant,
bearing bunches of pretty black berries. It requires a rich soil and
plenty of room for its widespreading branches. Cuttings will strike
under glass, or the seed may be sown in autumn. It flowers in August.
Height, 6 ft.