Growing Cacti from Seed

For a cacti enthusiast, growing plants from seed is an exciting and economic way of increasing a collection and providing presents for friends who are also cacti fans. Patience and the right combination of light, temperature and moisture are needed when growing cacti from seed – a great opportunity for cactus enthusiasts to extend their range.Peruvian Cereus

Buying cacti seed

Seeds of some cacti are generally available from garden centres and nurseries. If you want more unusual varieties you may need to go to a specialist cactus nursery. Your local garden centre should be able to provide you with names. Buy seeds packaged for the year they are to be sown. Old seed may take a long time to germinate.

The right compost

You can use a commercial cactus compost and add about one third gritty sand. An alternative to this is a soil-free mixture of equal parts sand and perlite. You can even make your own from two parts peat moss to one part sand but this will need to be sterilized. To do this, place the mixture in an oven for 30 minutes at 100°C (200°F or Gas mark ¼) or in a microwave on high for 2-3 minutes. The baked soil smells unpleasant but the odour quickly dissipates. Use spotlessly clean equipment and containers.

Cacti to grow from seed

  • Peruvian Cereus
  • Easter Lily cactus
  • Prickly Pear cactus
  • Bolivian cactus
  • Sea Urchin cactus

Sowing the seedcacti-grown-from-seed

Fill individual pots or a shallow seed tray to 1 cm (1/2 inche) of the top with the chosen potting mixture, having started with a layer of grit for good drainage. Place them in water at room temperature half way up the sides and leave until the moisture reaches the top of the mixture. Remove and drain well.

Before sowing the seeds firm down the top of the compost with a piece of wood or the base of another pot.

Seeds need to be evenly and thinly spread across the top of the pot to avoid overcrowding (ideally about 2.5cm (1 inch) apart). This can be difficult with very fine seed, which can be dealt with in two ways: either by trickling seeds out of a tiny corner hole in the packet or by picking up a pinch, and transferring it to the soil by rubbing finger and thumb together. Do not cover tiny seeds; others will need a sprinkling of sand to form a covering of the same depth as the seed size.

Providing ideal conditions

Cover the pots with a transparent lid, glass or a polythene bag and place in a warm spot such as on a shelf above a radiator or in the airing cupboard. As soon as the seedlings appear, move into a lighter position out of direct sun and partially lift the cover to allow ventilation.

If you intend to grow a lot of plants from seed it is worth buying a growing light or a fluorescent lamp to place above seedlings, as even light will promote strong all-round growth. A piece of foil or white card placed on the darker side of the tray will also help to encourage even growth.

Getting watering right is very important as too much will rot plants but too little will cause them to shrivel and die. The soil should be slightly damp but not damp enough for mould to grow. Water more often in hot weather than in cold. Use a mister and water at room temperature.

Be careful not to overwater the seeds. Dip the pot in water to wet the base. Water will be absorbed from the bottom of the pot.

Repotting

It is better not to repot cacti unless the plant becomes too large for its container. Before transferring, soak the potting medium in which the cactus is planted to make removal easier.

To transfer prickly cacti wear thick gloves or wrap the plant in a strip of fabric. If the rootball is difficult to dislodge, insert a pencil or a small stick through the hole in the pot base and gently loosen the clump.

Use a pot the next size up and slightly damp cactus compost for repotting. Place the plant in a light spot shaded from the sun and do not water for about a week.

Pricking out

When plants have reached the size of a small thimble they are ready for pricking out individually into small pots. First gently loosen the potting mixture around the roots and then remove the cacti with tweezers.

Provide a shallow layer of drainage in the new pot and then cover with commercial cactus compost. Firm down to about 1cm (1/2 inches) from the top edge

and make a central indentation wide and deep enough to take the spread of roots without disturbance. Position the cacti and gently cover the roots with more potting medium, then firm. The compost should be slightly damp.

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