Hints on Seed Raising
Strelitzia and similar
Do not chip or mark the
seed coat at all but merely remove the orange tuft and soak for up to 2
hours, or even overnight. Sow the seeds in moist sand, pressing them
into the sand until only a small part of the black seed is visible and
grow in a temperature of 75 degrees F in the dark and ensure that the
sand always remains moist. From 7 days onwards inspect the container
once a week and as soon as any bulges, roots or shoots are seen remove
the germinated seed and pot up in a compost of half peat and half sand.
We find that Strelitzias often produce a root without a shoot and we
have also found that the young shoots and roots are susceptible to
fungal attack. Therefore as soon as possible pot up and provide light
and fresh air. Germination can start within 7 days and carry on for 6
months or more.
Palms; Banana; Coffee; Mini-Orange; Tea; Cycads and similar
All these items can take
several months to germinate and are very erratic in germination. Soak
for at least 2 hours in warm water before sowing. (After soaking the
parchment shell on the Coffee seeds should be removed with the
fingernail). Sow in Levington or Arthur Bowers [note: a peatmoss
based mixture]. Compost and place in the dark in a temperature of
75 degrees F, keeping the compost moist at all times, but not wet.
Inspect regularly and occasionally dig around in the compost with a
penknife. We normally sow our seeds just below the surface of the soil
as we have found that sometimes they make a very vigorous root without
producing a shoot at all. If you find a seed with a root then it should
be excavated and potted up into a 3-4'' pot immediately when it will
produce a shoot. Cycads prefer to be potted up into a compost of half
sand and half peat. The Tea requires the above treatment but in a lower
temperature of 60-65 degree F.
Clivia and similar
Sow these seeds
immediately on receipt in Levington or a peat based compost, covering
with a 1/2 " compost. Water and place in the dark in a temperature of
65-70'F. Germination should occur within 3 weeks.
Ferns (Garden and Indoor)
The fern spore needs a
fine film of moisture over which to swim in order to complete the
process of reproduction, therefore a good peat compost, such as
Levington, ought to be used pressed down very firmly and which is a lot
more moist than one would normally have it in order to provide the
moisture film. The spore (seed) should be sprinkled close together on
the surface of the soil and not covered and the container should be
covered with a piece of glass and placed in diffused light, but not
darkness. It is essential to ensure that the compost remains moist at
all times. Germination which commences with the appearance of a film of
green jelly over the soil can take anything from 1 -5 months.
You may wish to try
germinating the fern spore on blotting paper which is placed in a saucer
and kept moist at all times. A transparent cover is inverted over the
saucer and the whole lot placed in a well lit but not sunny position.
You can actually see the fern spores developing and when you can see
small plantlets appearing along the jelly the blotting paper should be
lifted and placed on the surface of a container of Levington compost and
watered well. It should then be covered with a transparent cover which
can remain there until the plants are quite large.
Bromeliads; Cineraria; Calceolaria; Insect Eaters (Drosera, Nepenthes,
Sarracenias); Living Stones; Meconopsis; Rubber Plants; Saintpaulia;
Streptocarpus; Tibouchina; Xmas Cactus; Begonia and similar.
These seeds should be sown
on the surface of the compost and not covered. The compost should be
quite moist and we would recommend that you cover the seed container
with a piece of glass or clear plastic and leave in a temperature of
approximately 65 degrees F in a position which receives diffused light.
Once some of the seeds have germinated air should be admitted gradually
otherwise the seedlings may damp off.
Alternatively the seeds
can be sown on to moist blotting paper or kitchen towel placed in a
saucer. Cover with a transparent cover and place on a windowsill which
receives plenty of light, but not direct sunlight. Keep the blotting
paper wet at all times and when the tiny seedlings are large enough to
handle prick out into small pots. If the INSECT EATERS are sown using
the first method described the compost requires to be both moist yet
free draining. Use only pure peat with no fertiliser added to which
sphagnum moss should be added if available.
Alstroemeria; Bonsai; Clematis; Hardy Cyclamen; Eucalyptus; Flower Lawn;
Helleborus; Hosta; Primula; Iris and similar.
Sow the seeds in John Innes [note: a loam-based mixture] seed
compost, covering them with a thin layer of compost. After watering
place the seed container outside against a North wall or in a cold
frame, making sure they are protected against mice, and leave them there
until the spring. The compost should be kept moist but not wet at all
times, and if the seed containers are out in the open then some shelter
has to be given against excessive rain. In the spring bring the seed
containers into the greenhouse, or indoors on to a well lit but not
sunny windowsill and keep the compost moist. This should trigger off
germination. If the seeds do not germinate in the spring keep them in
cool moist conditions throughout the summer. As each seed germinates we
would recommend that you transplant it almost immediately into its own
Sow in John Innes seed compost, or something similar, and place each
container in a polythene bag and put into the refrigerator (not the
freezer compartment) for 2-3 weeks. After this time place the containers
outside in a cold frame or plunge them up to the rims in a shady part of
the garden border and cover with glass or clear plastic. Some of the
seeds may germinate during the spring and summer and these should be
transplanted when large enough to handle. The remainder of the seeds may
lay dormant until next spring.
Germination of some items,
particularly Alstroemeria, Clematis, Hardy Cyclamen and Christmas Rose
(Helleborus) may take take 18 months or more.
An alternative method for
growing PRIMULAS is to sow in a peat based compost which has already
been moistened and do not cover the seed. Cover the container with a
piece of glass or plastic and grow in the dark in a steady temperature
of 60F. This is quite adequate and over 65'F germination will be
inhibited. When the seeds start to germinate sprinkle a thin layer of
fine compost over them and when the seed leaves come through this, move
the box to a well lit place with a temperature of 55'F. At no time
should the seed box be in full sun.
Hardy Cyclamen have been
found to germinate best in total darkness at around 55-60'F. We have had
good results with the following method. Place the seeds between two
pieces of damp filter paper, Kleenex tissue, etc., then put into a
polythene bag and place this into an opaque container in order to
exclude all light. Inspect the seeds after a month and remove and prick
out as the seedlings appear, returning the ungerminated seeds to total
Soak the seeds for 24
hours and sow in Levington compost, or something similar, and place in a
temperature of 50-60'F. Germination can sometimes be slow.
Nertera Granadensis (Bead Plant)
We recently found that
this subject requires a well drained compost which is completely free
from fertiliser (e.g. moss peat and sand in equal parts). Sow by barely
covering the seed and place a sheet of glass over the container, and
leave in a temperature of 65-75'F. Turn the glass daily as excessive
condensation can kill the young seedlings. On germination the seedlings
look very thin and spindly and the glass should be removed almost
immediately and the seed container moved to a well lit but not sunny
position. Prick out as soon as possible into a compost of 50% pure peat
and 50% sand. Keep moist and shaded until established.
Cactus and similar
Make very shallow furrows
in compost with a plant label and sow in these. No seed should be
completely buried. Water from beneath and cover with glass and brown
paper or black Polythene. Place in a dark position in a temperature of
70-75F and keep moist. On germinating move to a light but not sunny
windowsill, give plenty of ventilation and water from beneath. Pot up
when they begin to overcrowd. During the first winter only keep warm and
do not allow to get too dry. If it is not possible to grow warm then
keep them drier. Subsequent years keep relatively dry through the
winter. Can be planted outside, plunged to the rim, all summer if
Successful germination of
seeds of some lilies requires a period of warmth followed by one of
Method 1. Put seeds in a
screw top jar in moist (not wet) peat and keep at 70-75F for 3-4 months.
Inspect regularly, any normal seedlings (that is having root and
seedling leaves) should be pricked out as they germinate. Any seeds
which produce roots but not seedling leaves, sow in a pan and keep at
32-40'F for 3 months. Seed leaves and normal growth will follow.
Method 2. Sow in a pan in
summer (warm spell); put in a frame (or outside covered by a piece of
glass) for the winter. Seeds will germinate in spring. Soil Humus rich
(peat or leaf mould) lime free and very free drainage (use 1/3 grit).
Never over-water, keep bulbs almost dry from November to March.
For more delicate seeds
A method which has proved
useful for not only small delicate seeds but for a wide range of types
is the Polythene bag method.
The seeds should be sown
on the surface of the moist compost, covered to their recommended depth
if necessary and the container is then placed inside a Polythene bag
after which the end is sealed with an elastic band. The bag should
'fog-up' with condensation within 24 hours and if this does not occur
place the container almost up to its rim in moisture until the soil
surface glistens, then replace in the bag and reseal. The bag is not
removed and normally no more watering is required until the seeds
germinate. However, it is wise, if left for a long period to check the
The seed container, bag
etc. should be placed in a well lit place with a steady temperature. As
soon as a fair number of the seedlings emerge remove the polythene bag,
lower the temperature a few degrees and provide plenty of light, but not
bright sunshine, to ensure that sturdy seedlings develop. It is also
helpful to spray the seedlings occasionally for the first 14 days.
Some seeds, e.g. Sweet
peas, lpomaea etc., have hard seed coats which prevent moisture being
absorbed by the seed. All that is needed is for the outer surface to be
scratched or abraded to allow water to pass through. This can be
achieved by chipping the seed with a sharp knife at a part furthest away
from the 'eye', by rubbing lightly with sandpaper or with very small
seed pricking carefully once with a needle etc.
Some of our geranium seeds
have already been treated in this way when you receive them.
Soaking is beneficial in
two ways; it can soften a hard seed coat and also leach out any chemical
inhibitors in the seed which may prevent germination. 24 hours in water
which starts off hand hot is usually sufficient. If soaking for longer
the water should be changed daily. Seeds of some species (e.g. Cytisus,
Caragana, Clianthus) swell up when they are soaked. If some seeds of a
batch do swell within 24 hours they should be planted immediately and
the remainder pricked gently with a pin and returned to soak. As each
seed swells it should be removed and sown before it has time to dry out.
Stratification (cold treatment)
Some seeds need a period
of moisture and cold after harvest before they will germinate-usually
this is necessary to either allow the embryo to mature or to break
dormancy. This period can be artificially stimulated by placing the
moistened seed in a refrigerator for a certain period of time (usually
3- 5 weeks at around 41 F). With tiny seeds it is best to sow them on
moistened compost, seal the container in a Polythene bag and leave
everything in the refrigerator for the recommended period. However,
larger seeds can be mixed with 2-3 times their volume of damp peat,
placed direct into a Polythene bag which is sealed and placed in the
refrigerator. Look at seeds from time to time. The seeds must be moist
whilst being pre-chilled, but it doesn't usually benefit them to be
actually in water or at temperatures below freezing.
Light also seems to be
beneficial after prechilling and so pre-chilled seeds should have only
the lightest covering of compost over them, if any is required, and the
seed trays etc. should be in the light and not covered with brown paper
Some seeds have a
combination of dormancies and each one has to be broken in turn and in
the right sequence before germination can take place; for example, some
Lilies, Tree peonies, Taxus need a three month warm period (68-86'F)
during which the root develops and then a three month chilling to break
dormancy of the shoots, before the seedling actually emerges. Trillium
needs a three month chill followed by three months of warmth and then a
further three month chill before it will germinate.
The above mentioned
methods (12-15) accelerate the germination process and help to prevent
seeds being lost due to external hazards (mice, disease, etc.) but
outdoor sowing is just as effective albeit longer. The seeds are best
sown in containers of free draining compost and placed in a cold frame
or plunged up to their rim outdoors in a shaded part of the garden,
preferably on the north side of the house avoiding cold drying winds and
Recent tests show that
much of the beneficial effects of pre-chilling are lost if the seed is
not exposed to light immediately afterwards. We therefore recommend
sowing the seeds very close to the surface of the soil and covering the
container with a sheet of glass. An alternative method especially with
larger seeds, is to sow the seed in a well prepared ground, cover with a
jam jar and press this down well into the soil so that the seeds are
enclosed and safe from predators, drying out etc.
We would also recommend
you consult No. 6 which contains further practical suggestions regarding
the special treatment of seeds.
Explanatory Notes for other columns in the
The usual time period in
which a particular variety will germinate given optimum conditions.
Seeds needing light should
have no newspaper, brown paper etc. placed over the trays. Seeds needing
dark for germination should be placed in total darkness. Seeds
with these strict requirements will have a L for light and a D for dark
in that column.
Slow and irregular
This is the column with
the "X". Not all seeds will show at once - prick out each seedling as it
becomes large enough to handle and don't discard the container until
well over the time suggested.
A steady temperature
between these limits is recommended-fluctuating temperatures can damage
a seedling in its critical early stages.
Most reputable seed
composts will be quite adequate and we have indicated where a loam based
type such as John Innes or a peat based type such as Levington would be
slightly more suitable. On no account should potting composts, which
have additional fertilisers, be used.
If in doubt sow shallowly,
but always ensure that the compost surface is damp. J.C.
=Just cover the seed with compost or sharp sand. S=Sow on the
surface and do not cover at all with compost.
Sowing in situ
Where recommended under
the heading of comments, these seeds can be sown out of doors. Moist
soil worked down to a fine tilth is essential. For hardy annuals and
perennials sowing can be carried out from late winter onwards as soon as
the ground is workable and has warmed up and half hardy annuals after
all danger of frost is passed.
Suggested Sowing Times
Many seeds, particularly
in the house plant group, can be sown indoors at almost any season of
the year. Others, for example bedding plants, have a much limited sowing
season because the plants need to be at just the right stage when
planted out. We therefore offer the following general guide to sowing
times. Your actual time of sowing will depend a great deal upon the
steady temperature you can maintain in your greenhouse/propagator, soil,
local conditions etc.
weeks before planting out
winter/spring or late summer/autumn
winter/spring or late summer/autumn
spring and late summer/autumn
Any time of
spring and late summer/autumn
Any time of
Any plant which is to be
planted outside (HA, HHA, HHP, HHSh.) should be well hardened off
beforehand. This is best achieved by placing the plants outside in a
cold frame for around a week before planting out. The frame can be left
uncovered during mild weather but always replaced at night.
Alternatively if no frame is available move the boxes outside to a
sheltered spot during the day and bring indoors at night.
Seed Germination Database
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