Raising Cacti

Table of Contents and IntroductionAfrican Violets: the Doyen of House PlantsAgapanthusAlstroemeriasAmerican SagebrushesAmerican WildflowersAndean Nymph - a pink mimulusAquilegias (Columbines)AuriculasAustralian AnnualsBellis Perennis (Daisies)Black-Eyed SusanBlue African LiliesBreeding DelphiniumsBreeding Fuchsias: Part 1: From SeedBreeding Fuchsias: Part 2: HybridisationBromeliads from SeedButterflies in Soy SauceCacti RaisingCampanulasChilean Bell FlowerChilly Treatment for Peruvian LiliesCollecting SeedConserving Annuals and BiennialsCosmosCucumbersCycads: Living FossilsCyclamen for IndoorsDahlias from SeedDamping OffErythroniumsF1 Hybrid - What Is it?F2 and Open Pollinated VarietiesFrom Obscurity to the Height of FashionGentiansGeraniumsGermination to Pricking OutGolden Impatiens - The StoryGrowing Alpines From Seed: Part 1Growing Alpines From Seed: Part 2Growing Bananas From SeedGrowing Cyclamen From SeedGrowing Eucalyptus From SeedGrowing Ferns from SporesGrowing Foxgloves From SeedGrowing Fritillarias From SeedGrowing From Seed: From Packet to SoilGrowing Hardy Ferns from SporesGrowing Hardy Geraniums From SeedGrowing Lewisias From SeedGrowing Magnolias From SeedGrowing Meconopsis From SeedGrowing Proteas and Related Genera from SeedHandling Small SeedsHardy Annuals: Part 1Hardy Annuals: Part 2Hardy CyclamenHardy SpurgesHelleboresIncreasing your Violas and ViolettasKeeping Records of Seed SowingLettuce - the Vital Part of any SaladLord Anson's PeaMagnolias - the Root of the ProblemMimulus from Seed to Seed in Sixty DaysNew Guinea ImpatiensOld-fashioned Sweet PeasOnions with EverythingPansies are not Difficult to Grow from SeedParsleyPerennials for American GardensPetuniasPhygelius - their cultivation and propagationPinks: Evocation of the PastPlants That Flower OncePrickly but NicePropagatorsRadishesRaising PalmsRaising PrimulasSalad Leaves - a lot to be desiredShow Stoppers Twice OverSowing SeedsSowing in Open GroundSowing to Feed our FriendsSturt's Desert PeaSweet Peas - Autumn SownSweet Peas - Sowing and GerminatingTall and HandsomeTechniques with Tiny SeedTexas BluebellThe Effect of Light on Germination and SeedlingsThe Nervous PeaThe Scarlet Welsh PoppyThe Search for the Yellow Sweet PeaToad LiliesTomatoesTreasure Hunt for TasteUnderstanding Latin NamesUnique Poppy (Mother of Pearl)Viability of VegetablesWeaning SeedlingsWill the Real Mimosa Please Stand Up

Many members of the cactus family flower surprisingly quickly when raised from seed and many of the slower types are not difficult. Dorothy Monks describes the treatment they need and their care after germination.

Cacti are no more difficult to raise from seed than many half-hardy subjects. Many can be flowered within two years or even earlier after sowing the seed and a fine collection can be raised in a few years.

The time of the year for sowing depends on conditions available. If you have a greenhouse available and a small heated propagator, it is possible to sow your seeds at the end of January or early February. However, if no heat is available it would be better to wait until late April or early May before attempting to sow your seed. The earlier the seed is sown the larger the seedlings grow before the winter sets in, which is a very important point. It is never easy to get small seedlings through the winter without heat and the stronger they are by the middle of October, the better chance you will have to see them through the cold dull season. Here I would emphasise that it is not recommended to raise seedlings in an airing cupboard as some varieties are extremely slow whilst others are much quicker. If you can maintain heat in your greenhouse in the region of 40-45F, it will help considerably and they will then make an earlier start into growth in the spring.

The best compost for raising cacti is a soil based compost such as John Innes Seed Compost which is readily available from most garden centres. The addition of extra sharp sand is very helpful, especially for the top inch of compost.

Seed sowing

It has been found that 4in (10cm) half-pans are very suitable for seed growing, as they do not dry out too quickly. Make sure all pans are sterilised and clean before sowing. If only a small quantity of seed is being sown of each variety the pan can be divided into sections using thin strips of plastic, but care must be taken not to get the seed mixed. Put some crocks (which have been well washed) into the bottom of the pans, then about 1in (2.5cm) of unsifted compost, fill up with sifted compost and sharp sand mixed, gently pressing down the soil leaving ½in (12mm) at the top of the pan. Place the strips for dividing and label all seeds sown with the date. If you are keeping a book of the varieties sown, date sown and when germination takes place, this can be a great help for future reference. Do not cover the small seeds with soil but very gently give a sprinkling of silver sand to anchor it. Large seeds should be pressed gently into the soil. When sowing fairly large seeds such as astrophytums, ferocactus, opuntia, etc, it is advisable to cover them with grit preferably sieved through a ¼in or ½in (6 or 3mm) sieve, this prevents them drying out and also prevents moss forming.

After sowing the pans they should be placed in a container with sufficient water to reach about two-thirds up. Once the dampness can be seen at the top of the soil, they are ready to be put into the heated propagator, 70-90F (21-32C) at the end of January or early February. The base of the propagator can be sand but the spaces of the pans can be filled with damp peat up to the rim. Place the cover over and shade with dark paper. However if it is not possible to maintain a temperature of around 70F (21C), it is better to wait until late April or early May, when general temperatures should be much higher, before sowing. The initial watering should be sufficient until some of the seeds are showing but watch very carefully and water with a fine spray if necessary.

As you appreciate some varieties take longer than others depending on the species, however some seedlings may show within seven to ten days whilst others will take much longer. Mammillarias may be up in a fortnight or sooner, again if the seed is a mixture of varieties, a few will germinate much quicker than others. It is really much better to sow each variety separately. Opuntias, ferocactus and some types of cereus can take a long while to germinate. It has been found that large seeds will germinate more quickly if they are well washed with hand-hot water before sowing.

I recommend you to cover your seeds after sowing, in fact it is really a must with most cacti seed. But whichever covering you choose, a propagator, frame, glass over the boxes or pans, or even polythene bags over the pans, it is very important to wipe the coverings daily to remove any moisture that has formed, as drips will rot the seed or seedlings.

As soon as the seedlings appear the paper or covering must be removed so that they can get some light, but if exposed to too much bright sunlight they can turn red in colour and may stop growing for a long while. Raise either the glass or frame cover daily once the seedlings germinate, so they can get light and air otherwise the seedlings will damp-off.

Damping-off

The disease called 'damping-off is a very troublesome enemy of tiny seedlings, it is therefore very important that the seed compost is correctly sterilised and pure clean water is used for spraying and watering. Once seedlings are attacked they are sure to die. If mildew is seen to form on the surface of the pans this could be caused by some seed pod husk when sowing the seed. It is very important to see the seed is free of all impurities.

Do not let your pans dry out whilst germination is taking place, but once the seedlings are up it is far safer to allow pans to become almost dry before giving any water.

Pricking out

It is important to prick out the seedlings as soon as they are ready. If left too long in the seed pans they may stop growing and once this happens it can be a long time before they start into growth again and very rarely make good plants.

The seedlings should be ready for pricking out when about three months old but some varieties may have to be left much longer. The best time to transplant is when the cotyledon (first seed leaf) has been absorbed by the plant proper, you will find that the seedling will have a good root system and can be potted without damage. The seedlings are best planted out 1in (2.5cm) apart in good strong trays which must be washed with disinfectant to prevent any diseases occurring. John Innes Potting Compost No. 1 can be used to which can be added about one part of sharp sand to every five of compost by volume to make it more porous. Level off the soil around the plants and firm gently.

When removing seedlings from the seed pan it may be possible to raise the seedlings altogether and gently separate the roots. Make sure the roots go well into the soil and try to spread them out. Label each kind with its name and the date when potted up, then water very carefully. The seedlings must be kept in a shady place, preferably under the bench of your greenhouse or similar position. On no account must they be in the sun. It is also important not to water too much until the seedlings start to grow again after moving.

The temperature still needs to be 70F (21C) or near. If it drops during the night it should not hurt the seedlings as long as it does not go below 50F (10C). Water the plants so the soil is quite damp and do not water again until it shows signs of drying out. Give plenty of air during the daytime but close up the ventilators fairly early in the evening.

The prime cause of seed not germinating is that it has been sown too deeply. Stale seed often has a very small chance of germinating, especially if it has been kept in poor conditions, so use fresh seed and buy from a reputable company. Do not expose seed pans to strong sun and be sure to bring them into light as soon as they are up.

Potting up

Do not be too quick to pot up the small seedlings, leave in the pricking out boxes until they start to touch one another. At the first potting the seedlings should be put into 2 or 2½in (5 or 6.5cm) pots depending on the variety or species. Some seedlings, such as mammillarias, may even flower in their seed boxes or pans following the year of sowing, but other flowering cacti - rebutias, notocactus, gymnocalycium, lobivias etc. generally take two years and others such as opuntias, cereus and ferocactus may take much longer.

After the plants are potted up and growing well, they should be able to stand a winter temperature of 45F (7C) so long as they are kept dry with a few exceptions already mentioned.

A weak solution of liquid tomato fertiliser can be used about once a month during spring and summer on most varieties of cacti.

As you appreciate the cactus family extends to many thousands of varieties and species and it is possible to mention only a very small number here, but the basic instructions will cover the raising of practically all varieties. However mention of the following epiphytes, which grow naturally on trees. They require slightly different growing instructions, especially as they flower from Christmas onwards. Examples include Zygocactus truncatus, Schlumbergera bridgesii (Christmas Cactus), Schlumbergera gaertneri (Easter Cactus), Rhipsalidopsis rosea (Whitsun Cactus). All these types require low to medium light, a porous yet moisture retentive compost and need watering as soil dries out. They should be kept drier in autumn to encourage bud formation. They need a humid atmosphere and will benefit from a weekly mist spray from spring to late August. Just as the buds begin to form place the plants in a cool position where they can be kept in darkness at least 12 hours each night as long as the temperature does not drop below 45-50F (7-10C).

Epiphyllums are different again and require full light from early autumn to spring and partial shade after flowering.

The bottom of the greenhouse is a good spot or they can be plunged outside in a shady position. It is necessary to check all pots before bringing them in to ensure that there are no worms in the pots. After flowering, plants should be rested for six weeks when they need only enough moisture to prevent the soil becoming completely dry. At all other times the compost should not be allowed to become too dry. Water less frequently in late autumn and winter. Overhead spraying is also beneficial, when they need only enough moisture to prevent the soil becoming completely dry. Aporo-cactus (Rat's Tail Cactus), needs rich open compost and plenty of water in summer.

Pests and diseases

Care must be taken to ensure the propagating frame is free from pests.

Mealy Bug. It is vital to kill mealy bug promptly. Always use a good insecticide, which can be painted on with a fine brush, kept especially for this purpose.

Root Mealy Bug. Take off all soil and destroy it, wash the roots thoroughly with methylated spirits, then thoroughly wash this off letting the roots dry after treatment before replanting in completely fresh sterilised soil. Always cleanse and sterilise frames and all other items used when replanting.