Cacti and Succulents from Seed

SEED SOWING METHOD

A shallow pot or pan will be needed. I would recommend a 2 inch (5 cm) pot for a packet of around 30 seeds, a 2 3/4" (7 cm) pot for 100 seeds or a standard seed tray for 1,000 seeds.
The seed compost should be light and airy and should remain that way i.e. it should not become hard and compacted with age.

A good general mixture to use is John Innes Seed compost with 30%. coarse grit (1 to 3 mm grains) mixed in. If you prefer to mix your own compost, a good general mix would be - 60% coarse grit, 30% sieved sandy loam (topsoil), 10% moss peat. For epiphytic varieties e.g. Christmas and orchid cacti, the mixture needs to be more acid and I would use - 50% coarse grit and 50% moss peat.

The seed pan should be filled to within 1/4' (0.5 cm) of the top and lightly firmed to give a level surface. Sprinkle the seed evenly over the surface and press lightly into the soil with a flat surface e.g. a matchbox. This is to ensure that the seeds are in close contact with the soil and just held in position.

Very large seeds such as Opuntia and Aloe can be buried with a little of the soil mix. To discourage moss and attack by peat fly, a top dressing of 1/8 th inch (3 mm) deep grit can be given. The grit for this top dressing should be sieved to give a particle size of 1-2 mm. Extremely small seeds such as Parodia and Echeveria are best sown on top of this grit and then gently misted to wash them down into it.

After sowing, stand the seed pan in half an inch of water and leave until the surface is thoroughly moist. Rainwater is best whenever possible as it is slightly acid, which aids germination.
For this first soaking, adding a fungicide, such as Cheshunt Compound or copper fungicide to the water, will help to prevent fungal attack.

Remove the seed pan from the water and cover with a sheet of glass. Recent research has suggested that the vast majority of succulents do not require darkness to germinate; in fact some must have light, so it is not really necessary to cover with brown paper as is so often advised.

Place the seed pan in a warm place, with shade from direct sunlight. A germinating temperature of 60 to 70 deg. F (15 to 20 deg. C) is a good general temperature. Seeds can be sown on a sunny window-sill from April onwards without any artificial heat, but with a propagator, sowing can commence in January. I have found from experience that with or without a propagator, the best germination is always obtained if the temperature is allowed to fluctuate. It can be allowed to rise to over 100 deg. F (40 deg. C) during the heat of the day, falling to 60 deg. F (15 deg. C) at night. For this reason, even if you have a propagator, it is perhaps best to delay sowing until April, when advantage can be taken from the natural diurnal temperature fluctuations.

Most seedlings will germinate between two days and three weeks although some erratic varieties can take up to six months or more. Most cactus and other succulent seed will germinate well and you should expect an average of 60% germination.

Don't throw pots away if nothing comes up the first time. If, say after six weeks, nothing has appeared, remove the pot from the propagator, dry it out for two or three weeks, then soak it and pop it back into the propagator again. This can be repeated several times, to imitate alternate wetting and drying cycles in nature. If still no success, leave the pot dry for twelve months and try again.

Some varieties which come from areas experiencing very cold winters may need to go through a cold spell before they will germinate. These will be varieties such as Opuntia, Tephrocactus and Pediocactus. Pots can be wrapped in polythene and placed in the ice compartment of the refrigerator for one or two weeks (at minus 5 to minus 8 deg. C) and then returned once again to the propagator.

Once the majority of seedlings in the pan have germinated, the glass needs to be removed to reduce the humidity a little, but still continue to shade. A muslin cover to the propagator is ideal at this stage as it provides shade and allows good air circulation. Regular misting should be carried out, as the seedlings must not dry out for the first three months. This is the most delicate stage, when the seedlings are most vulnerable to fungus “damping-off" diseases. The most important fact in growing from seed is that during this first three months the soil should be evenly moist, but not wet. The correct balance will only be learned with practice

Carnegia seedlings germinating on vermiculite

At around three months, when the seedlings begin to develop their first spines and begin to look like miniature cacti, they can be allowed a little more light and they should dry out for very short periods between mistings.
At this stage, check that the seedlings are receiving the correct amount of light. If they are all bronze-coloured and not growing, they are receiving too much light. If they are all tall, pale and spindly and falling over, then give them more light. Many cactus seedlings are naturally a little red in colour, so you need to strike a happy medium.
Also at three months, I would advise that feeding can start, with a very weak solution at first, say half strength cactus-feed.

It is best not to disturb the seedlings too soon as the roots on young plants will be very delicate. The seedlings can be transplanted when they become quite tightly packed in the seed pan - usually after 9 to 12 months. They can be transferred carefully - as roots are still quite delicate - into individual small pots or into rows in seed trays. The latter method is favoured as young cacti appear to grow better with company.

The seedlings should be watered lightly through their first winter if temperatures over 55 deg. F (14 deg. C) can be maintained. Otherwise they should be treated as adults and kept dry all winter.

With extremely small seeded types, or if your busy schedule prevents regular checks during the early months, there is an increasingly popular method of seed-raising. Seeds can be sown into pots, into moistened, sterilized seed compost and then sealed into polythene bags. These bags can be placed in a propagator or hung on wires in the greenhouse. Care must be taken to ensure that the moisture level is just right - no excess moisture in the bottom of the bag. A microclimate will have been created, moisture will circulate and no watering will be needed. Condensation on the bags will usually provide sufficient shading.

The most important factor here is cleanliness. Pots, soil and seed must be disease-free at the start. Distilled water is a good idea here, to avoid introducing algae and fungi. Once started, bags can be left for several months without opening, and can often be left until the seedlings have established good root systems. It is a good idea to slit the bags a few weeks before pricking-out to acclimatize the seedlings to normal conditions.

A FEW SEED-SOWING TIPS -

At first sign of fungal damping-off disease (Seedlings go watery and collapse) drench with a fungicide such as Chinosol or Cheshunt Compound.
If seedlings seem to disappear overnight they are being eaten by peat fly (sciara fly) larvae. Dust or drench with an appropriate insecticide.
Build-up of moss can be reduced by watering with Bordeaux mixture - but don't use it more than three times as a build-up of copper compounds will be harmful to the seedlings.
Prevention of moss formation is better than cure. Don't over-water, ensure adequate ventilation, make sure the soil is not too alkaline by using lime-free grit, make sure there is a little moss-peat in your mix, and use rain-water whenever possible.

Some seeds may germinate readily whilst others in the pot can be easily seen, just lying on or near the surface. The ungerminated ones may well germinate if transferred to a fresh pot of compost (say with tweezers) and popped straight back into the propagator. This is because a build-up of alkalinity from your tap-water may be inhibiting germination in the old pot, but the new soil, especially if you use rain-water (or cold tea - without milk!) will still be acid and provide optimum conditions.

Seed viability varies with age. Some varieties will only germinate when fresh, others only when 12 months old or more, so always keep your sown pots for a second try the following season. Don't assume very old seed is no good. Living Stone seed for example is still 95% viable when 8 years old.

Keeping a record of variety sown, the date and % germination will be very useful if you plan to sow seed regularly. The simplest method is to keep your empty seed packets, number them, and similarly number your pots. You will only then have to write labels for those that actually germinate.

Have fun with your seeds. You never quite know what you’ll get!

You can download a super FREE pdf document on cactus seed-raising here

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