The half-hardy perennial varieties are often
grown as annuals and are hybrids between the Argentine
species Petunia nyctaginiflora and Petunia violacea.
The stems are leafy and attain a height of a
foot or more, bearing many tubular flowers, three
inches or more across at the mouth, of varied
colours, mostly purple, violet-blue, rose and
There are a number of garden varieties with huge
frilled flowers attractively veined on a self-coloured
ground, usually with a deep purple blotch at the
Seed should be sown under glass in late January
to March, care being taken to sow it thinly to
avoid damping off.
The seedlings are potted when an inch or so high,
and it is important to avoid over-watering.
Planting out-of-doors where the plants are to
bloom may be carried out in early June when all
risk of frost has passed.
Propagation is from seed, or cuttings taken in
The flowering season is from late June to September.
Half Hardy Perennial.
Six inches to two feet.
Flowers of several colours (white and shades of
purple and crimson), July and August.
Though a perennial under glass, in the open garden
the plant should be treated as a half-hardy annual.
Plants in small pots may be obtained from the
nurseryman about the end of May, and put out in
a sunny open position on soil that is not too
Seed may be sown early in March, in a temperature
ranging between 50° and 65°; the seedlings
are slow in reaching a manageable size, and may
need to be delicately pricked out with the point
of a knife or slip of wood.
This should be done as soon as possible, if green
mould appears on the surface of the soil in the
The heat should be kept up to an average of 60°
until the plants are rooted and begin to grow
in their new quarters; then harden them gradually
by admitting air, avoiding droughts and blasts
of easterly spring winds, and water judiciously.
It is convenient to put the plants at their first
pricking-out into thumb-pots; they may remain
in these till it is time to plant out in May,
and can be turned out of them into the ground
with little disturbance.
If pots be thought too troublesome, shallow wooden
boxes may be used, or a bed of soil may be made
up under the frame.
In any case, the plants should be kept close to
The best Petunias for out-door culture are singles
of good distinct colouring; those described in
the catalogue as “Single Bedding”,
not the large doubles and fringed flowers which
are more suitable for greenhouse decoration.
A good strain of seed will produce “self”
flowers in white, crimson, rose and pinkish lilac,
and flowers striped and blotched with these colours.
Petunias at all stages of their growth are liable
to flag and droop and die without visible reason.
The cause appears to be an attack by some fungoid
growth on the stem at the ground-line. There is
apparently no remedy.