Growing advice - Impatiens
Impatiens grow wild in most tropical and warm to temperate regions
of the world, except Australia, New Zealand and South America.
The genus contains about 850 species. They are made up of annuals,
evergreen perennials and sub-shrubs. They can be found growing
in a variety of generally damp places including near streams,
lakes and in woodland. All types have a brittle, succulent stem
with fleshy, lush foliage. The flowers are sometimes hooded, singles
(5 petals) or doubles and are borne singly or in clusters. The
colour range includes white, yellow, red, pink, purple and orange.
The flowers are sometimes striped or barred, some are also bicolour
or margined in a contrasting colour. Best removed after flowering,
then come the exploding seed pods. Some species including the
New Guinea Hybrids have been developed for their bronze, yellow
or variegated leaves.
Impatiens grow well in semi-shade and make excellent long-lasting
summer colour plants in tubs, pots, baskets and pouches, as well
as beds and borders. They make very good all year round house
plants and can be over-wintered in a cool room indoors or a frost-free
greenhouse.
Breeders have spent many years developing new and exciting varieties
of impatiens and other plants. The first seed from the new cross
is called an F1. As seed can only be taken from the first cross
for the plant to grow 'true', this tends to become rare and expensive.
Here at Thompson & Morgan we try to give you, our customers,
the best range of varieties to choose from and believe the best
way to let everyone benefit from the hard work involved in breeding
new plants is to market small quantities of F1 seed. We hope that
giving the average content of a pack will help you to pick the
right plant for your planting plan. F2 seeds (seed taken from
the F1's daughters) are much cheaper but don't generally have
all the advantages or colour ranges of the F1s. Seed collected
from an F1 and sown by yourself will generally not perform as
well as the mother plant.
How to Sow for Best Results
Impatiens seed is quite small and must be handled with care.
The seed can be sown from early spring (February to May). Sow
in a 7.5cm (3in) pot, on the surface of the compost, then cover
with a very fine sprinkle of Sow Lite or free draining compost.
Sow Lite is a natural mineral (known as vermiculite) which, when
exposed to very high temperatures, expands to produce a honeycomb
like structure. Gardeners can benefit from this structure, as
it helps to absorb excess moisture, insulates the seed and allows
oxygen through the compost to the germinating seed. After sowing
place the pot in a propagator in a brightly lit place, but not
in direct sunlight. If you don't have a propagator, wait a few
weeks before you sow until the air temperature has risen. Place
the pot inside a clean, clear plastic bag and seal with an elastic
band. This will help hold in the humidity and heat required. The
results may not be as good as with a propagator, as it is more
difficult to maintain the critical temperature required for germination.
The compost should be moist, but definitely not wet. Wet compost
(which can even be the case straight from the bag) will be cold
and reduces the oxygen that the seeds need to germinate. It may
even stop the seeds germinating at all. If the compost is too
dry this will also cause problems. If this is the case, sprinkle
a small amount of warm, clean tap water over the compost and leave
it to soak in thoroughly. When the compost has absorbed the water,
take a small handful and squeeze it in your fist; if water drips
out it is too wet, so leave it for a short while in a well ventilated
spot to dry off. If it holds together when you open your hand,
it's just about right. You can now fill your pot with the moist
compost and you don't have to water it again before you sow the
seed.
The soil temperature is critical for good germination. It has
to be a steady 21C - 25C (70F - 75F). The temperature must not
fluctuate, as this can cause poor or failed germination. The seedlings
should start to appear in about 10 to 21 days. Remember that impatiens
seeds are very temperature and light sensitive. In a cold year
or if you live in a cold area, it would be advisable to wait a
few weeks before sowing, also keep your propagator or pot in a
bright area. Too hot or cold soil temperatures, strong or dull
light, even a sudden drop in temperature at night may cause the
seedlings to bolt and stretch. This stress on the seedlings may
encourage "Black Leg" or root damage or death. After
germination lower the temperature to around 18C and regularly
check the compost for dryness. If this is the case, add a little
clean water from below, being careful not to over water. Too much
water can kill seedlings, as it can spread "damping off fungi"
and encourage other moulds and diseases.
When the seedlings are large enough to handle, (this should be
after about 3 - 4 weeks) without touching the stem, just handling
the leaves, transplant them carefully into 7.5cm (3in) pots. Grow
on in a cool (12C - 15C), frost free, well lit place, avoiding
direct sun light. To ensure really well branched plants, pinch
out the growing tip after they have rooted well into their pots.
Finally, pot them on into 15cm (6in) pots or baskets, (depending
on the variety, or where you want them to end up) and grow them
on for a few weeks in a frost free greenhouse or similar. Gradually
acclimatise them to the outside conditions by placing in a sheltered
place during the day and bring them back inside at night. Watch
out for cold winds as well as pets, birds, mice etc. After all
risk of frost has passed they can be left out or planted into
their final flowering position for you to enjoy.
Pest and disease
Keep an eye out for greenfly, whitefly, red spider mite (two-spotted
mite) and other pests. If they become a problem use a recommended
proprietary brand of insecticide. Botrytis (grey mould) may affect
the flower buds and cause them to drop, so try to avoid watering
from above and increase the ventilation. Pick off any badly affected
flowers and spray with a recommended proprietary brand of fungicide.
Water the plants regularly, but take care not to over-water and
feed with a general all-purpose liquid fertiliser every 10-14
days once the flower buds have started to develop. Don't forget
to deadhead and remove any damaged flowers or leaves. Deadheading
will promote more flowers and help reduce the spread of any pests
or disease.
Over-wintering impatiens as house plants
Try to avoid disturbing pot grown plants, as changes in conditions
by moving the plant from one place to another may cause bud drop.
This may also be due to the temperature being too cold, or the
air around them being too dry. If grown as a house plant try increasing
the room's temperature and misting the plants in the morning.
Try not to mist later on in the day as water left on the leaves
and flowers overnight will increase the risk of Botrytis (grey
mould).
Impatiens are frost-tender, so to over-winter plants growing
outside, lift the plants before the first frost, and pot them
up into a good potting compost. Put them on a bright (south, east
or west-facing) windowsill and water well. They should continue
to flower all through the winter.
Impatiens grown from cuttings
Impatiens can also been grown from cuttings. Some of the more
exotic varieties will not come true from seed and have to be grown
this way. To take cuttings, choose a shoot without flowers or
remove flowers and any buds. Take the cutting about 5-8cm (2-3in)
long, trim off at the base with a sharp knife and remove the lower
leaves. Insert several cuttings around the edge of a 7.5 cm (3in)
pot filled with moist cutting compost. Place the pot inside a
clean, clear plastic bag and leave on sunny, frost free windowsill
until they have rooted. Pot each one into a 7.5cm (3in) pot removing
the growing point and any flower buds that appear, so as to encourage
a strong and bushy plant. When the cutting is well rooted, treat
as a seed-raised plant and gradually acclimatise it to outside
conditions or grow on your windowsill as a house plant.
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