Seed Germination Database

The following data is provided by Thompson & Morgan Successful Seed Raising Guide. This guide is out of print.

A seed is an embryo plant and contains within itself virtually all the materials and energy to start off a new plant. To get the most from one's seeds it is needful to understand a little about their needs, so that just the right conditions can be given for successful growth.

One of the most usual causes of failures with seed is sowing too deeply; a seed has only enough food within itself for a limited period of growth and a tiny seed sown too deeply soon expends that energy and dies before it can reach the surface. Our seed guide therefore states the optimum depth at which each type of seed should be sown. Another common cause is watering. Seeds need a supply of moisture and air in the soil around them. Keeping the soil too wet drives out the air and the seed quickly rots, whereas insufficient water causes the tender seedling to dry out and die. We can thoroughly recommend the Polythene bag method (No. 11) which helps to overcome this problem. Watering of containers of very small seeds should always be done from below, allowing the water to creep up until the surface glistens.

Most seeds will of course only germinate between certain temperatures. Too low and the seed takes up water but cannot germinate and therefore rots, too high and growth within the seed is prevented. Fortunately most seeds are tolerant of a wide range of temperatures but it is wise to try to maintain a steady, not fluctuating temperature, at around the figure we have recommended in our guide. Once several of the seeds start to germinate the temperatures can be reduced by about 5 degrees F and ventilation and light should be given.

Some perennials and tree and shrub seeds can be very slow and erratic in germination. This may sometimes be due to seed dormancy, a condition which prevents the seed from germinating even when it is perfectly healthy and all conditions for germination are at optimum. The natural method is to sow the seeds out of doors somewhere where they will be sheltered from extremes of climate, predators, etc. and leave them until they emerge, which may be two or three seasons later. Dormancy, however, can be broken artificially and our section Nos. 12-16 deals with this.

HINTS ON SEED RAISING

1. Strelitzia and similar
Do not chip or mark the seedcoat 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.

2. 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 (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 soilatid 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.

3. 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.

4. 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 plantlettes 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.

5. 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.

6. Alstroemeria; Bonsai;
Clematis; Hardy Cyclamen;
Eucalyptus; Flower Lawn;
Helleborus; Hosta; Primula;
Iris and similar.

Sowing OCTOBER-FEBRUARY. Sow the seeds in John Innes 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 pot.

Sowing MARCH-SEPTEMBER. 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 darkness.

7. Freesia
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.