Growing Cactus Plants from Seeds

Equipment Set Up | Water Needs | Rain Water | Cactus Seed Starter Soil | Soil Flies | Shore Flies | Preventing Fungus Gnats | Bacillus popiliae |Bacillus thuringiensis subsp. israelensis | Use of Fertilizer | Nurse Plants | Molds | Bacillus subtilis | Destroy mold | Witch Hazel | White vinegar

Most cacti seeds can be grown indoors under artificial lights for at least the first few years, but they will grow more with some direct sunlight. There are problems like mold and insects that can completely wipe out new seedlings, and these kinds of problems need to be avoided. Results will vary according to a wide range of conditions like temperature, light, the kind of water and growing mediums, so success in growing cactus plants from seed may take some trial and error methods. The fastest and healthiest seedlings will be the ones that can be grown outdoors in sun light, but there are still many problems to avoid whether seedlings are grown indoors or outside.

Equipment Set Ups

Flower Pot in Window:

A plastic covered flower pot in a sunny window is an ideal location for seed germination, and will become like a small greenhouse.

Sprinkle seeds on top of some soil in a small flower pot, and cover the pot with a clear plastic bag. One good way is to place the entire pot into a bag and leave a small opening for air circulation. Another way is to cover to top of the pot with clear plastic and secure it with a rubber band. Then cut a small hole in the plastic to allow a small amount of air to circulate. Either way set the bagged flower pot in a sunny window location and make sure the soil stays moist for at least 2 weeks.

After seeds germinate the plastic bag will need to be removed gradually, rather than all at once. The bag can be opened or cut open more and more over a few months so that the environment may dry gradually. Cactus seedlings need much wetter soil than adult plants, so even as the soil dries out it will quickly need more water. Keeping the plastic on the flower pot will cause the soil to dry out more gradually, and the importance of keeping a moist environment will largely depend on the size of the seedlings. Very small seedlings like Aztekium or Strombocactus may need a plastic cover for almost a year after germinating because they are very small seedlings. Larger seedlings like Ferocactus may no longer need a plastic cover after the first month, but will still need to be watered frequently. Alternating soil between wet and dry conditions will be good for the seedlings, but a plastic cover may be helpful for the first month up to the first year depending on the seedling sizes.

A windowsill is an ideal location for cactus seedlings for the first few years of life because cactus seedlings need less light than adult plants. The window will reduce the intensity of sunlight and all but a few species will grow very well in a southern window. When seedlings are more than two years old the may be transplanted into larger flower pots and as they get older they may benefit from more direct sun light in outdoor locations as long as the weather is warm enough for the species.

A Flower Pot or Seed Tray Outdoors:

In most cases seeds can be germinated out doors if they are covered by some protective shade cloth to keep them from being harmed by heavy rain. The seeds will germinate if and when the temperature conditions are right and the soil stays wet long enough to promote growth.

It takes more patience to germinate cactus seeds outdoors than under controlled indoor conditions because seeds will wait for the ideal conditions to occur before beginning to grow. Outdoor seed starting has the advantage of potentially producing the healthiest plants possible, but seeds may take months to years before growing. If cactus seeds will grow outdoors this method is surely - the most for the least - and is the greenest method because it is closer to natural conditions than any other method.

The most common method is to cover a flower pot with shade cloth to protect the seeds from too much sun and hard rain. Rain can wash seeds away and cactus seedlings need less light than adults and will grow better with some protection for the first few years of life until they are ready for full sun light.

Outdoor seed starting will work much better using a corse medium more gravel oriented and less like sand. A coarse medium will stand up under rain more and provide a more natural like protection for the seedlings to chose the amount of sun they need. Seedlings will hide under small rocks or stay between them and grow there for months before reaching up for more sun. It is possible to have seedlings growing well and be unable to see them because they will hide in the first few months of life under the surface of the growing medium. It is even possible to grow seedlings without protective shade cloth if the medium is composed of a coarse gravel and the flower pots can be set in the sun and rain without any additional protection.

A plastic or glazed flower pot will work well and much better than a terra-cotta pot because plastic and glazed pots will help retain moisture for the seedlings. Fill the flower pot with a coarse gravely medium and sprinkle the cactus seeds on the surface of the medium. In the spring leave the flower pot out in the sun and rain and the seeds will begin to grow when the right temperatures and enough rain fall occurs for them to grow.

Germinating seeds out doors in a humid climate will come with the risk that there may be a wide variety of insects and molds that can destroy the young plants. Shore flies and soil flies (or fungus gnats) can destroy cactus seedlings whether they are germinated outdoors or indoors, but there are even more insects in outdoor conditions. Along with small flies sometimes called, Sciara flies there are animals like millipedes, sow bugs & slugs and all of they love to feed on young cacti.

It is important to use some kind of repellant to keep insects away from cactus seedlings to increase their chances of survival. Cedar wood chips are very effective at keeping most insects like fungus gnats away from cactus seedlings. Sprinkling some cedar wood chips around the young seedlings will help prevent most of these cactus eating creatures at bay.

An even more effective way to minimize the damage insects may do to seedlings is to use a product called Mosquito Beater by Bonide. This contains a microbe called Bacillus thuringiensis subsp. israelensis and it is designed to feed on mosquito larva, but will also feed on the maggots of small flies if they lay their eggs on the young cactus seedlings. There is more information further down on this web page and in some climates this kind of product is a must for growing cactus seedlings.

Germinating Cactus Seeds Under Artificial Light:

In general the larger cactus seeds are the more difficult they will be to germinate indoors, but the majority of species have small seeds and will grow very well under artificial lights for at least the first six months of their lives. It is possible to grow most species of cacti under artificial lights for as long as two years, but these plants will have to have real sunlight and the sooner they have sun the faster they will grow.

Many species of cactus seeds may be easily germinated indoors under artificial light in seed starting trays. Four foot florescent light fixtures with house plant bulbs are very energy efficient and some plant light bulbs for aquariums also work well. A good set up is to place t full sized seed trays under one 2 bulb 4 foot fixture with the bulbs at a distance of 6 to 10 inches above the soil. Most plant light bulb directions recommend a distance of 18 to 24 inches and this will also work, but closer distance is very effective for cactus seed germination.

It is very helpful to have a timer which will automatically turn the lights on and off at set times. A day of artificial light needs to be about 14 - 16 hours and the florescent light fixture can raise the soil temps high enough to germinate most cactus varieties especially if the trays are covered with a clear plastic lid.

The amount of light and heat kept on the seeds can also be enhanced by surrounding the light area with a reflective material. There are many reflective types of insulation materials available in hardware stores that reflect both light and heat. It is important to keep in mind that the light fixture itself needs an air space that will prevent it from overheating while it is operating.

Using a heating pad under the seed tray may improve germination and survival rates depending on the structure of the set up and the specific temperature requirements of the cactus species being grown. It is possible to use heat and light reflective materials around the seed trays as long as the light fixture itself is kept in a save operating temperature range. It is a good idea to use a thermometer and know how much heat is generated by the equipment set up before attempting to start seeds. If the soil temperature turns out to be too low they can be improved with a heating pad, and if the temperatures are too high perhaps the equipment may need to be modified to allow for more air circulation and cooler conditions. Germination rates of the seeds and the following survival rates of cactus seedlings will depend a great deal on soil temperatures. Whether a heating pad is needed will depend some on the specific cactus seed variety, the structure of the equipment set up and the ambient room temperatures. It is good in all cases to allow the seeds and/or seedlings to cool down at night, so a heating pad needs to be turned off when the lights go off too.

Cactus plants require cooler night time temperatures to grow and having both the lights and heating pads on a timer may help prevent accidentally cooking the seedlings to death.   

Water Needs

Seedlings need much more water than adult cacti.

Most cactus seeds need to be kept very wet to germinate, but if they fail to germinate after a month it may be better to dry them out completely and try germinating them again at some later time. Cactus seeds are very tough and they can go through many wet and dry cycles before they germinate, but most varieties will germinate anywhere from 3 days to 4 weeks from the time they are planted. The presence of water will cause the seeds to grow if the light and temperature conditions are right. Cactus seeds can last over a few years with several germination attempts while adjusting the conditions until they will grow. Keep them wet when trying to germinate them and dry them out when they need to be stored. Even thought these plants have a reputation for loving dry climates cactus seeds require a wet soil period of a month in many cases to stimulate germination under artificial lights.

The frequency of watering cactus seedling will depend on how soon the seeds germinate, how fast the soil dries out and the age of the seedlings. After seeds germinate they can be alternated through wet and dry periods. Essentially the younger cactus seedlings are the more frequently they require being watered. According to The Cactus Primer, by Arthur C. Gibson and Park S. Nobel; seedlings that are as much as 50 days old can survive dry conditions for about 10 days, seedlings that are 100 to 150 days old can tolerate dry conditions for about 50 days, and seedlings that are about a year old may survive dryness for as long as 150 days. Cactus seedlings are much more dependent on wet conditions after they first germinate and can take longer dry periods as they get closer to a year old. The data for these dry time survival periods are from observations of seedlings growing in natural conditions. It is possible for the conditions of an artificial florescent plant light and heating pad to be even more severe than the dessert areas where these plants naturally grow. If a one year old seedling is left without water for 150 days in an indoor seed starter it is very unlikely that it will survive past 50 days. Death by dehydration is often more likely than giving cactus seedlings too much water in a seed starter. This is probably because the soil is very shallow and the soil will dry out completely very quickly under artificial lights. In nature cactus seedlings can begin to put down deep roots and reach places that retain water for long periods of time. Cactus seedling growing with seed starter equipment won't have access to any hidden water in places like rock cracks. Cactus seedlings grown indoors under lights will need frequent waterings even without a heating pad and seedlings older than a year will still likely need to be watered on a weekly basis.   

Rain Water

Germinating and growing cactus seeds will require clean water from a natural or pure source like rain or distilled water. Unfortunately tap water will create an unhealthy environment for cactus seedlings mostly because of chemicals like chlorine and other tap water contaminates. Chlorine free water from a natural source like rain water or some kind of purified water like distilled water will be much healthier and increase the survival rate of cactus seedlings.

If it is unavoidable to use tap water it can be modified with white vinegar, and that will help keep cactus seedlings healthy. Use 9 drops of white vinegar in one quart of tap water or .26 cc of white vinegar in one litre of tap water and the water will be safer to use on cactus seedlings.   

Cactus Seed Starter Soil

The easiest way to create a seed starting medium is to mix a small amount of house plant potting soil with sand, but there are several factors to keep in mind when choosing the sand and other ingredients. The sand needs to be clean and free of clay deposits. Sand sold for play sand and beach shore sand should be avoided because they usually have a high clay content. Raw Peat Moss works poorly, but many growers have success with Milled Sphagnum Moss as a main ingredient beside sand. Another addition for a seed growing medium is perlite and it can be used in large amounts for cacti. Clean water like rain or distilled water are very important as well as light and temperature factors will still be more important than soil, because cactus seedlings will tolerate almost any soil. It is however, important that the soil be Ph neutral or slightly acidic and that the growing medium will dry quickly like a sandy mixture.

The following are some basic ideas to keep in mind:

It is a bad idea to use top soil form lawn or garden areas which are rich in humus, because they usually retain too much water for too long and will easily support the growth of fungus that will kill the cactus seedlings.

It is very important for the seed starting medium to dry quickly and sands are fast drying, inexpensive and are an excellent ingredient for starting cactus seeds. The sand needs to be very clean and free of clay and decomposing organic mater. Ocean beach sand should be avoided because the salt content is toxic to cactus seedlings. Lake beach sand, straight from the shore, is best to avoid because it may have insects ore nematodes which will be harmful to cactus seedlings . Sand purchased from landscaping supply companies may also have insects or other life forms which can be harmful to cactus seedlings, but lake shore and landscaping sands can work very well if they are cleaned and sanitized. The most cost efficient sand that needs the least amount of cleaning will be brick mortar sand and this is usually easy to find at hardware stores or landscaping companies.

It is important to sanitize sand from most sources and a few easy methods can make almost any sand into a good cactus starting medium ingredient. heat sanitizing is a quick and easy way to kill most harmful organisms and a few hours in the oven at 250 degrees is a good method. Another way is to cook the sand using organic hardening methods, and there is a lot of information in resource books and on the web.

Sand is one of the best ingredients to start cactus seedlings in and a small amount of potting soil will be helpful to the seedlings as long as the mix will dry quickly. Another ingredient that will cause faster drying times is perlite, but even if perlite is used the success of the medium will mostly depend on the quality and cleanliness of sand.   

Soil Flies

The greatest cause of cactus seedling mortality in a more humid four seasons climate will likely be due to soil flies or shore flies,a and these small insects are often also called fungus gnats or Sciara flies. These are species of small flies who are attracted to decomposing organic matter and whose larvae often feed on the roots of plants. Here in Wisconsin I've observed 4 distinct species of flies in their larvae stage feeding on cactus seedlings, but unfortunately I lack enough knowledge to identify them by their scientific names.

There is a greenish bodied kind with a darker head that feeds inside of the seedlings until they are hollow. This species only seems to be interested in very young seedlings and the damage they do is very easy to notice. They are present in the summer months both indoors and outdoors, and only seem to be active in the warm weather. Other species which thrive on house plants may be present all year long and can attack cactus seedlings even in winter.

A species of fly which makes a very small translucent maggot feeds mostly on the roots of cactus seedlings and are very hard to detect. They do a lot of damage and can go completely unnoticed until nearly all of the seedlings in a pot are dead. The seedlings turn dark , shrink and if they are already developing spines it is even more difficult to see that they are dying. After the maggots have done their damage they leave behind shrunken empty rootless spine covered dark shells, which use to be cactus seedlings.

Another kind of maggot, which may actually be a kind of shore fly is larger than the others and yellow like a very small banana slug. This one stays under the soil and feeds on the base of the plants, but it is very hard to find, and causes the seedlings to rot from the roots up. The stem part of the plant looks healthy while the roots are shriveling away and then the remaining stem rots and usually turns to a fluffy ball of mold.

The most interesting and unusual fly maggot I've found feeding on cacti seedlings is a very small white maggot. They look like a small crescent shaped bit of sand, perlite or perhaps a small fleck of limestone. I found them feeding at the eh base of cactus seedling stems, but sucking the plants from the outside rather than digging into the seedlings. Occasionally I could find these maggots attached higher up on the stems, and if I disturbed them they would fall to the base of the plants. There they would either hide under the soil or play dead next to the seedlings. In almost all cases cactus seedlings that had these maggots feeding on them would die from a fungal infection within 3 months of the attacks.   

Shore Flies

Shore flies are common in regions where lakes and rivers are a major part of the landscape. They can be found in gardens, houseplants and seed starters even several mails away from lake or river shore lines. Their larva can and will feed on the roots of cactus seedlings and the results are surely terminal for the plants. This is a pest that needs to be prevented, because getting rid of them after the infestation begins will mean that it is too late to save most or all of the cactus seedlings.   

Preventing Fungus Gnats or Soil Flies and Shore Flies

Cedar wood chips are being used to help keep flies away from seedlings.

Cedar wood chips sprinkled around the cactus seedlings is a very effective way to keep the flies away. Cedar wood oil is toxic to cactus seedlings, but the wood chips seem to be harmless to the cacti and the seedlings we grow with cedar wood chips are remaining free from soil fly infestations.

It is very necessary to find a way to prevent these insects from attacking cactus seedlings because the results are almost always fatal. Even if the insects are discovered feeding on the seedlings and destroyed the damage they cause will almost always result in a fungal infection and these seedlings will usually die within a few months after they have been infested.

Insecticides are almost useless because killing the insects after they are discovered is almost a measure that is too late. Prevention strategies will increase the chances for cactus seedling survival over a post infestation strategy, although killing off soil fly larva to prevent them from spreading may do some good too. There are insect repellant products and it may be worth while to try something rather than wait until the flies arrive and then try to get rid of them.   

Bacillus popiliae

Milky Spore Powder was designed to destroy soil dwelling grubs like Japanese Beetle Larva, and appears to also be effective against much smaller insects like soil fly - shore fly - Sciara fly types of larva. Milky Spore Powder contains Bacillus popiliae and this bacteria kills insect larva which inhabit soil, thus it is highly likely to destroy soil dwelling fly maggots.

Small flies whose larva live and feed in soils can be serious problems to many species of cacti, especially when they are only seedlings. I began applying Milky Spore Powder to cactus starting medium and growing seedlings in 2006 hoping that it would be effective at stopping fly larva attacks. We have seen larva infestations on cactus seedlings, applied this product and after several days there are no longer any larva feeding on the seedlings. This is only circumstantial evidence and fails to make a concrete proof, like having the dead bodies of soil fly larva. From what we've seen there is plenty of circumstantial evidence to show that the viable Bacillus popiliae spores are destroying fly larva that live in soils. We've included Milky Spore Powder is seed starting mediums and the seedlings have grown without being attacked by soil flies, and the cactus seedlings are doing well.

Bacillus thuringiensis subsp. israelensis

An effective way to minimize the damage insects may do to seedlings is to use a product called Mosquito Beater by Bonide. This contains a microbe called Bacillus thuringiensis subsp. israelensis and it is designed to feed on mosquito larva, but will also feed on the maggots of small flies if they lay their eggs on the young cactus seedlings. This product or products containing this microbe may be sprinkled on the surface of the growing medium and re-applied month to month as the rain de-solves the product over time. This is the most effective way to protect cactus seedlings from the various species of small flies whose larva feed on organic vegetative matter. These flies begin to breed in the early spring and various species will be laying eggs through the growing season and even into November. Some of these species of flies are frequent guests to house plants and even when cactus seedlings are brought indoors for the winter this kind of protection is still a good idea.

If you use this product called Mosquito Beater by Bonide to prevent cactus seedlings from being destroyed by fly larva there are a few considerations to keep in mind. The product can be sprinkled on the surface of the growing medium and when the seedlings are watered it will become effective. In a wet condition the product may produce some white mold, but this will subside as the surface of the soil dries out. This produce may need to be reapplied every few months and the length of time it remains effective may vary according to the frequency and amount of water being provided to the cactus seedlings.

Growing cactus seedlings outdoors in a wet climate has the significant advantage of letting the rain provide the water cactus seedlings need to get a good start in life. The worst draw back will be that a wet climate also has a multitude of insects that my destroy the seedlings. Even if seedlings are grown indoors under artificial lights the small flies that lay eggs on plant matter will still be a problem. If an indoor set up is going to be used it will still be a good idea to use Mosquito Beater to control fungus gnats.

Products with Bacillus thuringiensis are considered to be an excellent way to control destructive fly larva that live in soils by many growers, and in many climates this kind of product will be essential to cactus seedling survival.   

Use of Fertilizer

After the first 1 to 6 months of growing cactus seedlings some amount of fertilizer will be helpful in most conditions, especially if the starter medium is mostly a nutrient poor sand. What type and how rich of a fertilizer solution will depend on the seed starter medium. Soil testing kits are available at many green houses or web based garden supply stores. Cactus plants will need plenty of Phosphorus and Potassium, but much less Nitrogen than most other plants. Nitrogen is usually the first of these three nutrients that the soil will lose, so it is likely that a fertilizer with all three will be useful, but likely at a weaker concentration than what will be recommended on the product direction labels. There are both chemically fabricated and natural or organic gardening products available, and we use natural fertilizers like sea kelp and fish emulsion based products.

Too much fertilizer is counter productive, so take care to avoid causing the soil to become too rich which can cause distorted and elongated growth in some species of cacti. Whether you prefer more chemistry set types or natural products there will be improved results growing seedlings with week concentration fertilizers, especially if the seed starting medium is mostly a nutrient poor sand. If seedlings can be grown outdoors or moved outdoors in the growing seasons where they will be watered by rain they will grow very well without needing fertilizers.   

Nurse Plants

Buffalo grass is being used here as a nurse plant for Escobaria seedlings.

Using a nurse plant can reduce problems with mold and help cactus seedlings have a stronger survival rate. Buffalo Grass works very well and can be started in a seed tray, and even though it grows better outdoors it will grow well under artificial lights too. Start the grass seeds in the starter tray about 3 to 6 months before planting the cactus seeds to give the grass a good head start. Then plant the cactus seeds at the base of the grass plants and keep them wet and warm to prompt the cactus seeds to germinate. As the cactus seeds grow the medium will need to be dried out in-between watering, so eventually the grass will dry up and perhaps even die from dehydration. Buffalo Grass can survive very long dry periods and can look dead for half a year before growing new green shoots. The protection from mold provided by grass will be most effective in the first few months and when the cactus seedlings are over six months old they will grow better if the Buffalo Grass is allowed to perish. The cactus and grass can be grown together for many years, and many species of cactus plants will have a better survival rate if they are grown with nurse plants.   


Even if you have a really exceptional seed starting medium there will be some problems with mold. The worst that can happen with mold is the development of a long slender type which will walk quickly across the surface of the soil as it grows. This variety of mold will destroy both seeds and seedlings if it is allowed to persist and needs to be destroyed quickly. Briefly raising the acid content of the soil surface will usually stop this sort of mold problem. Many growers recommend sprinkling a small amount of sphagnum moss on the soil surface and drying out the soil surface briefly will help too. We've found that squirting this mold with vinegar is also effective if done twice in 2 days. Too much vinegar will also harm cactus seedlings and it becomes risky to exceed 2 applications of vinegar if seeds are already growing when this kind of mold starts. Garlic oil products designed for repelling insects also can knock out this kind of mold problem too, and these are less likely to harm seedlings than vinegar.

Mold can be a very lethal problem to cactus seedlings if allowed to persist in the seed starting medium. They can be brought to the seedlings by insects, but often they are simply the result of a small amount of decomposing organic matter. Seeds that die often turn to fluffy balls of mold and other bits of organic matter in the soil may grow a white fluffy mold too. This problem can usually be fixed simply by removing the bit of organic matter or dead seed before it begins to spread across the soil.

As the seedlings begin to grow and the soil can be kept dryer for longer periods of time between waterings, and mold will become less and less of a problem as the seedlings mature. Some seedlings will die and then begin to mold and usually the other seedlings will be unaffected, but it is still a good idea to remove dead moldy seedlings.

As a special note: growing Pediocactus and Sclerocactus seeds in a medium that lacks any aggressive kind of mold resistance to begin with will almost always produce little white balls of mold instead of plants. Cacti with larger seeds like Pedios and Scleros are better grown outdoors where mold is much less likely than with indoor growing conditions. These species require more attention to mold prevention that the information given here, but this will cover most mold problems that happen with most cactus seedlings. There are thousands of cactus species that will grow well without molding under lights with sandy soils most people can put together using sand and potting soil. With the exception of growing Pedios and Scleros most mold problems can be handled if the seedlings are checked daily and the mold problems are addressed quickly.   

Bacillus subtilis

Serenade Disease Control is a certified organic product that contains Bacillus subtilis. The label reads that it, "Controls: Anthracnose, Bacterial Spot, Leaf Blight, Early and Late Blights, Rust, powdery Mildew, Grey Mold and Black Mold, Scab."

This product can be used as an ingredient in cactus seed starting medium to help prevent molds and as a natural way to destroy them if they start. We've noticed an increased survival rate for cactus seedlings when including a very small amount of this product in our seed starting mediums, and the environment in mind, all ingredients are pure and natural, food or pharmaceutical grade." It is important to use this product in very very small amounts for it to work effectively with cactus seedlings.   

Destroy mold

Garlic Pharm was designed for repelling insects away from plants, but it is also great for repressing mold growth which may occur when growing cactus seedlings.

"Garlic Pharm" is made by "Pharm Solutions Inc." and it seems to be easy to find in greenhouses for purchase. The label says, "This product contains no alcohol or anti-microbials" and is an "All-natural & Biodegradable" product "For Organic Production". The garlic product is designed to repel insects and small mammals and the label reads, "Your pure and natural answer to Garden Pests. Designed with your family and the environment in mind, all ingredients are pure and natural, food or pharmaceutical grade."

Pharm Solutions Inc. does have other products designed to attack molds and mildews, but the Garlic Pharm is safer for cactus seedlings than many other products because it contains no soaps. It is often happens that mold can grow along with germinating cactus seeds, and the mold can often be fatal to the seedlings if left untreated. Dead seeds that mold can be picked out of the growing medium, but there are molds which grow across the surface of the soil too. These surface molds will usually wipe out every seedling as it grows across the top of the soil. The Garlic Pharm is very effective in stopping these molds and saving the lives of otherwise doomed cactus seedlings. Spraying the seedlings and mold generously will repress the mold growth and sometimes one treatment is enough. Often, the mold will return in a few days and another treatment will be needed, and sometimes it takes several treatments every few days to totally stop the mold.

There are other items useful for destroying molds like; vinegar, sphagnum moss, alcohol or witch hazel, but too much of these kinds of things can also harm the cactus seedlings. I've tried to overdose cactus seedlings by drenching them and saturating their growing medium with Garlic Pharm, but the seedlings have continued to thrive. If there is a toxic level for Garlic Pharm on cactus seedlings we can't find it, and compared to other methods we've tried this one is our favorite for eliminating molds when they happen to cactus seeds and seedlings.   

Witch Hazel

"Lemon Witch Hazel with Aloe Vera," made by Thayers, has been useful in helping to keep cactus seedlings alive. We've used this Witch Hazel to knock out both molds and insect infestations on young cactus seedlings. Often times some mold will start to grow along with the germinating cactus seedlings and a light spray is often enough to stop the mold and leave the seedlings alive. This lemon version is less effective against infestations on adult cacti than "Medicated Superhazel with Aloe Vera", but has helped save a lot of cactus seedlings for us.

When soil flies have laid eggs among cactus seedlings or soil mites are eating the young roots "Lemon Witch Hazel with Aloe Vera," is a natural ingredient and effective way for eliminating these insects. Often times when cactus seedlings start to damp off the cause will be the presence of soil fly larva or soil mites, and if these plants will have been compromised by insects feeding on them fungal infections will occur. Once the seedlings have been damaged in this way there is no way to save them, but if these problems are caught soon enough at least some of the seedlings may survive after the insects are destroyed. Lemon Witch Hazel with Aloe Vera made by Thayers has been a very useful part of growing cactus seedling for us, and we believe we have been able to help save many cactus seedlings from being devoured by soil fly larva and soil mites with this product.   

White Vinegar

Using vinegar to stop mold from destroying cactus seedlings.

Vinegar has been very useful for us in stopping some kinds of mold when germinating seeds. There are many kinds of mold that can become problems when growing cactus and succulent plants from seed, and usually it is only a matter of removing some decaying organic matter. Often a seed which fails to germinate will turn into a fuzzy ball of mold and removing this small mass of fungus from the seed medium will be the end of this kind of mold problem.

There are also problems with mold caused by Sciara flies laying eggs in medium for germinating cactus seeds, and vinegar is unlikely to do much in the way of helping to stop this problem. More information on Sciara flies and cactus seed starting. White vinegar can also be used to modify tap water for watering the seedlings and more information is on this page in the rain water section.

The kind of mold vinegar has proved itself to be effective in stopping is a long slender structured mold that rapidly grows across the surface of the soil. This kind of mold growth is very destructive to seedlings and can wipe out an entire seed tray in less than a week if allowed to grow unchecked. In repeated trials a very gentle misting of vinegar on this kind of mold has stopped it, and saved hundreds of newly emerging cactus seedlings. The applications were a gentle mist applied with a spray bottle only one time, and the vinegar also landed on newly emerging seedlings too. The seedlings have always survived the vinegar application, but it is surely the case that too much vinegar would harm cactus seedlings too. With this kind of mold, which is very fatal to seedlings, it is well worth the risk to apply a small amount of vinegar to the mold and seedlings in order to stop the mold.   

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