A unique cacti that is easily grown from seeds, but have an unusually short life span for cacti, only lasting a few years. The flowers are nocturnal, lasting for only one night, but a number are produced in succession, they like to bloom.
Best raised in six inch pots, a good inside plant. It is a small, yet stunning cacti best known for its large and fragrant flowers. In addition to that, it is self-fertile—meaning that the plant will self-pollinate without assistance or a second flower, leading to the production of many seeds each year.
LET852 Peniocereus greggii v. transmontanus
Light shade to full sun. Heat resistant. Little water required. Hardy to 20°F. Grayish green trailing stems reaching 10 or more feet, often growing into trees. Strongly scented white flowers. USDA: 9-10.
JB247 Echinopsis subdenudata
Echinopsis subdenudata is a globular, almost spineless or with very short cream spines that produces splendid night-blooming, white funnel shaped, fragrant flowers up to 9 inches long. Hardy to 32 degrees. Water sparingly, provide good drainage.
Zones 9 and abover outside, but great container plant for inside.
JB217 Monstrose Apple Cactus ( Cereus peruvianus monstrosus )
Cereus peruvianus monstrosus is an incredibly unique specimen that grows taller than most any other succulent in a columnar form. As it grows more mature, it blooms (rarely) small white flowers that give way to orange to red fruit that look similar to an apple. Flowers only open at night however, and live for less than 24 hours before closing. Because of its extensive taproot system and relatively no need for regular watering, Monstrose apple cactus can be planted in areas with little to no irrigation such as in desert style landscapes, medians and hot, arid climates. Plant in full sun and well draining soil to avoid root rot. Mealybugs and scale are only minor pest issues for this wonderfully low-maintenance plant. For zones 9-11 outside, or easily grown in containers.
LET574 Tree Cholla ( Cylindropuntia imbricata )
This is a tree-like cactus with a short, woody trunk and a number of upright candalabra-like branches. A mature trunk will have a 4 inch or larger diameter and the plant can reach 8-10 feet tall, in some cases taller.
The spiny stems are jointed and cylindrical. Large, showy flowers open out wide and are reddish-purple in color. Fruits ripen from green to rose to yellow.
Considered invasive in places in the SouthWest as the joints that fall to the ground regenerate new plants quickly.
It can take severe drought and hard freezes and is suitable to USDA Zones 6 and above.
LET575 Cereus forbesii
Cereus forbesii is a species of columnar cactus whose native range is Bolivia to N. Central Argentina. The species is a branched, shrubby cactus that can grow up to 23 feet tall in height, but is usually found at a height of 6-7 feet tall. It grows in arid hills, forests, plains, and on the edges of salt flats.
USDA: 9b-11. Hardy to 32° F, protect friom frost. Full sun. Columnar, branching growth to 14' tall, 5" in diameter. Moderate water summer, light water in winter. White nocturnal flowers, up to 3 inches long. Origin: Eastern Bolivia, Argentina. Good container plant, start with small containers and step up in size every couple of years.
JB259 Peruvian Tree Cactus ( Armatocereus laetus )
A stunning, robust, treelike cactus to 20 feet tall with a candelabra-like crown of thick, ridged, bluish gray branches. The white flowers are followed by small, spiny, green fruits. Native to southern Ecuador and Peru, where it grows in dry valleys of the Andes in scrublands on rocky slopes. In cultivation it is best suited to drier warm temperate climates in USDA Zones 9 to 11. Regular water summer, little water in winter. 4" long, white nocturnal flowers. Origin: Northern Peru.
LET578 Acanthocalycium violaceum
USDA: 8-10. Frost hardy to 25°F. Solitary to clumping growth, up to 2' tall, 6" diameter. Regular water summer; winter keep dry. Full sun to light shade. white to violet flowers. Origin: Banos de Zapallar /San Luis Argentina.
LET577 Argentina Tree Cacti ( Armatocereus procerus )
A tree type cacti with great ornamental appeal. Solitary to clumping growth, up to 20' tall, 6" diameter. Regular water summer; winter keep dry. Full sun to light shade. white to violet flowers. Origin: Banos de Zapallar /San Luis Argentina. USDA: 8-10. Frost hardy to 25°F.
TWT180 Mammillaria columbiana
A very nice container cacti for windowsills and tables. Clumping, globular cactus to 6" tall. Bright red pink flowers spring and summer. Light shade. Hardy to 32 degrees. Water sparingly, provide good drainage.
JB193 Echinocereus scheeri
An easy to care for cacti that does very well in pots. Full sun, needs little water and good drainage. Forms clumbs of yellowish green stems to 28" tall. Pink flowers will last up to a week, opening at night and may close during the hot part of day. Origin: Mexico. Zones 7-10 outside, good container plant. Hardy to 25 degrees.
SF401 Pilosocereus chrysacanthus
A robust, tree-like cactus to about 15 feet tall with a much branched, candelabra-like crown of fairly slender, succulent, deeply ribbed, bluish green shoots to about 3 inches in diameter.
The edible fruits have deep purple flesh. Pilosocereus chrysacanthus is native to dry regions in southern Mexico in the states of Guerrero, Puebla and Oaxaca and adapts well to cultivation in warm temperate and dry tropical climates in USDA Zones 10 and above.
LET368 Clustering Barrel Cactus ( Ferocactus robustus )
This cushion-forming cactus is native to the Mexican States of Puebla and Veracruz and forms a large mound that can reach a diameter of as much as 15 feet across, with sometimes hundreds of thick, ridged shoots to 2-3 feet tall, densely armed with reddish spines. A magnificent, very drought tolerant and fairly cold hardy cactus, suitable for dry temperate areas in USDA Zones 9 and above.
This is a most unique cacti to have in your collection.
SF251 Queen of the Night ( Selenicereus Grandiflorus )
A gorgeous night blooming cactus with large white flowers that grow to several inches. The flowers are also fragrant, with a mild vanilla-like scent. Bears spiny, 2-4" long red ripening fruits that are edible and fairly tasty, with much similarity to the dragon fruit. There are numerous subspecies and crosses of this species.
An easy care, fast growing cactus, with a clambering habit, also excellent if used in a hanging basket.
Primarily grown as a container cacti indoors, it is hardy to zone 10a (30 - 35F) outside.
SF342 Mexican Claret Cup ( Echinocereus coccineus )
Clumping growth habit to 16" tall. Often becomes a large colony. An outstanding species that blooms in mid-spring with a profusion of hummingbird-attracting orange to scarlet-red flowers held over a mound of tight clustering stems. Flowers attract bees and hummingbirds. For zones 4-9.
SF346 Ecuadorian Tree Cactus ( Armatocereus godingianus )
Tropical cactus, keep from frost. Full sun to part shade. Columnar tree cactus, up to 30' tall outside, but a very nice container cacti while young. Regular water summer, little water in winter. Large (up to 4" long) white nocturnal flowers. Origin: Ecuador. Hardy to 35° F.
JB173 San Pedro Cacti ( Trichocereus pachanoi )
A dark green columnar cacti that can reach 10-20 ft. tall. Bears showy white fragrant flowers at night that can reach 9" across. Cold hardy outside to 15 degrees when mature. Good cacti for beginners.
Evidence suggests San Pedro was cultivated as early as 200 to 600 BC and selected for its psychoactive effects High altitude adaptation means it can survive at -10°F, while easily propagated foot-long sections placed in the soil can develop roots in a few weeks. Once established, San Pedro can happily grow about a foot per year.
LET842 Huancabamba Peruvian Torch ( Trichocereus peruvianus Huancabamba )
Discover the rich history and cultural significance of Trichocereus peruvianus var. Huancabamba or the Huancabamba Peruvian Torch Cactus. Found high in the Andean mountain deserts of Peru and Ecuador, this cactus has been used by the monks of a pre-Inca culture known as Chavín in their ritualistic ceremonies to diagnose spiritual links to a patient's illness. Its active compound, mescaline, has been reported to be present in a concentration of 1.2% in the dried cactus, and it also contains varying phenethylamines and other substances in minimal proportions. Today, Curanderos or medicine men of northern Peru still use it for spiritual and medicinal purposes. A close relative of the San Pedro cactus.
TWT185 Trichocereus Hybrids Mix
Seeds are collected from plants with all colors of the rainbow, from red, orange, yellow, apriocot, magenta, pink, ect.
3723 King Cup Cacti ( Echinocereus triglochidiatus )
One of the most attractive hedgehog cacti is the King Cup, which grows in clumps as much as 3-4 feet across but usually smaller. The bright red-orange flowers often cover the whole plant, which is cylindrical and low-growing, often hugging up against some larger plant.
The numerous flowers grow at the top of the stems, all about the same height, giving a full view of all the flowers at one glance. They last for several days. The flowers vary slightly in color as a result of soil type or genetic differences.
Zones 7-10. Hardy to 20°F and lower. Full sun to light shade in hotter desert gardens. Needs little water and good drainage.
SF318 Melocactus neryi
A small solitary cacti that does very well in small clay pots. Easy to care for, fuss free and unique look. Cold hardy to about 30 degrees.
3688 Notocactus magnificus
A picture perfect cacti for pots or patio. Prefers light shade or a small amount of full sun. Regular water in summer, keep dry in winter, root rot prone. Origin: Brazil. Zones 9b-11.
LET303 Notocactus grossei
(Syn: ERIOCACTUS grossei) USDA: 9b-11. Light shade. Hardy to 32° F. Full sun. Regular water in summer, keep dry in winter. Solitary or clumping, globular to columnar growth to 12" diameter. Yellow flowers. Origin: Paraguay.
SF417 Giant Barrel Cacti ( Echinocactus platyacanthus )
The largest of all barrel cacti is native to the deserts of northeastern and central Mexico and can reach a height of up to 15 feet, with a diameter of 4 feet or more. It grows relatively slowly and forms a deeply ribbed, dark green stem armed with short brown spines. It does best in dry, warm temperate climates in USDA Zones 10 to 11 and should be kept as dry as possible during winter.
D8433 Barrel ( ferocactus )
A good selection for inside or outside. The plant assumes a
columnar barrel type shape and can grow up to 3' outside. It is
a heavy bloomer with large flowers. Very stout spines with a
hooded central spine.
SF380 Blue Barrel ( Ferocactus glaucescens )
An excellent indoor pottted cacti. A smallish cactus that forms a usually solitary, bluish green, deeply ridged, robust and thick stem to about 20 inches tall and almost 20 inches wide, giving it a barrel look when mature. It is fiercely armed with small clusters of showy, broad, yellowish spines and has yellow flowers.
It is native to dry juniper woodlands in central Mexico. It is a robust and easy to grow cactus for desert regions and also makes a very attractive potted plant.
The flower is lemon yellow, funnel-shaped and up to 1.6 inches in diameter.
Zone 9b and higher outside, widely grown inside.
SF395 Mexican Lime Barrel ( Ferocactus pilosus )
A stunning barrel cactus, up to 8 feet tall, endemic to the northern and central desert regions of Mexico, with dense reddish spines and beautiful yellow to red flowers.
Traditionally, the flower buds of Ferocactus pilosus are harvested and eaten by the indigenous population. Will thrive in hot, dry climates and will tolerate mild frost once established.
SF389 Glory of Texas ( Thelocactus bicolor )
The Glory of Texas is a species of flowering cactus, widely distributed in the northern Chihuahuan Desert of the USA (Texas) and Mexico. Plants are usually solitary, but may form clumps.Growing to 20 inches tall, it is a perennial with spiny, ribbed, succulent stems. Large daisy-like flowers, up to 3 inches in diameter, are borne in summer. The petals are purplish-pink, fading to white. The inner petal tips form a circle of red surrounding a prominent yellow boss.
This cactus is grown as an ornamental. A warm, dry, sunny spot in sharply-drained specialist cactus compost must be provided. It has gained the Royal Horticultural Society's Award of Garden Merit.
IP359 Lady Fingers Cacti ( Echinocereus pentalophus )
Lady Fingers is one of the most beautiful flowering cacti and once mature, the plant is loaded with blooms. The stems root as they creep, and some clones are stoloniferous. They are easy to grow inside in wide, shallow pots or flats. Stems that grow beyond the pot will hang down for two feet or more and be covered with blooms during flowering stage.
Should not be grown in full sun, actually prefers about 30 percent shade, making for a good patio plant. Easy to grow in pots, zone 9 and higher outside.
JB237 Silver Torch Cacti ( Cleistocactus strausii )
A fast growing branching columnar cacti from South America that
is covered with eye-catching silvery spines when older. Starts
out solitary when young, but branches out and creates it's own
clumps as it matures. Can grow to 6 ft. tall. Good container
plant for inside, it requires a warm climate if grown outside.
Will not tolerate temperatures below 41 degrees F.
LET103 Cleistocactus morawetzianus
A shrubby, columnar cactus with slender, erect stems that are branching from the base and growing to about 8 feet tall if grown outside, modertely armed with grayish spines. The tubular flowers are white. Cleistocactus morawetzianus is native to dry, interandean valleys in central an southern Peru. It is easy to grow in most warm temperate climates. It makes a great container plant for cooler zones, should be protected from freezing.
JB250 Beavertail Prickly Pear ( Opuntia basilaris )
Widespread in deserts throughout the southwestern USA, this attractive cactus forms dense clusters of large, bluish pads that rarely have spines. The flowers are brilliant purple-pink. It is hardy to USDA Zone 8 and need excellent drainage in more humid regions.
Makes a nice container plant and will live many years in a pot provided it is not overwatered. The Beavertail Cactus is a medium-sized to small prickly pear cactus, depending on variety, growing to about 24 inches tall. A single plant may consist of hundreds of fleshy, flattened pads. These are more or less blue-gray, depending on variety, growing to a length of 6 inches and are maximum 4 inches wide and about 1/2 inch thick. They are typically spineless, but have instead many small barbed bristles, called glochids, that easily penetrate the skin.
LET854 Spineless Prickly Pear ( Opuntia ellisiana )
A great pad cacti without spines! It is also extremely heat tolerant, and its low spreading nature makes it an ideal choice for roadways plantings and even green roofs. During the summer months it sports large, bright yellow blossoms that provide nectar for hummingbirds.
These are followed by attractive and edible bright red fruits. Spineless, with few glocids. Full sun. Heat tolerant. Little water. Hardy to 16°F. Slow growing to 2' tall; 8' wide. Origin: Mexico, Texas.
LET855 Giant Prickly Pear ( Opuntia streptacantha )
A large cactus, native to eastern and central Mexico between 1900 and 2800 m. It forms a shrub or small tree to 12 feet tall with a robust trunk and a much branched crown of large, flattened, spiny shoots. Flowers are yellow to orange. Like other Opuntia it is easily grown and hardy to severe drought and moderate freezes.
D8422 Giant Saguaro ( Carnegeia gigantea )
Also known as Suhaurao. If you want a cacti that will outlive you and may reach a
height of 30 ft. or more, then this one is for you. Its the familiar cacti shown in western film. Has a solitary trunk and outstretched limbs that resembles arms. Makes a nice container plant when young.
IP349 Organ Pipe ( Stenocereus thurberi )
This species has several narrow stems that rise vertically, growing from a single short trunk just above the ground level. These stems are about 6 inches thick and grow to a height of 16 feet, however it has been known to reach 23 to 26 feet tall.
These stems rarely branch but rather grow annually from the tip of the last growth. The mature plant can reach a width of 12 feet. Each stem has 12 to 20 inch high ribs that bear dark brown to black spines that turn gray as it matures. It takes 150 years to reach maturity.
The older plants produce three-inch funnel-shaped white flowers annually which are open at night and close by the morning and have a purple or pink tint to them. These usually grow during April, May, and June. The organpipe cactus is usually pollinated by bats.
The plant also produces fruit about the size of a tennis ball. Beneath the fruit's spiny exterior is red flesh that has been described as tasting better than watermelon. This fruit has traditionally been harvested by the Seris, who call the plant ool, and is used as a medicine.
IP290 Bishops Cap ( Astrophytum myriostigma )
A. myriostigma is a spineless cactus defined by the presence of three to seven (usually five) pronounced vertical ribs which define the cactus' shape when young. Very easy to grow and care free, it is commonly grown as an ornamental plant in cactus collections.
D8497 Peruvian Torch Cacti ( Trichocereus pervianus )
Stout 6-12 ft. columnar cacti with bluish-green color. An easy to grow,
fast growing cacti that features large 10" sweet scented flowers that bloom
at night. Cold hardy to 25 degrees when mature.
Image:Imartin6, CC BY 3.0 , via Wikimedia Commons
LET733 Elephant Cactus ( Pachycereus pringlei )
Pachycereus pringlei (also known as Mexican giant cardon or elephant cactus) is a species of large cactus native to northwestern Mexico, in the states of Baja California, Baja California Sur, and Sonora. It is commonly known as cardón, a name derived from the Spanish word cardo, meaning "thistle"; additionally, it is often referred to as sabueso (or "bloodhound"), which is possibly an early Spanish interpretation of the native Seri term for the plant.
Large stands of this cactus still exist, but many have been destroyed as land has been cleared for cultivation in Sonora.
The cactus fruits were always an important food for the Seri people, in Sonora; the dried cactus columns themselves could be used for construction purposes, as well as for firewood.
A symbiotic relationship with bacterial and fungal colonies, on its roots, allows P. pringlei to grow on bare rock, even where no soil is available at all; the cactus has the distinction of being lithophytic as needed. The root’s bacterial colonies can fix nitrogen from the air and break down the rock to expose hidden sources of nutrients. The cactus even evolved to maintain this symbiotic bacteria within its seeds, serving to benefit by taking it on as part of its very physical biology.
Morphology
A cardon specimen is the tallest living cactus in the world, with a maximum recorded height of 63 feet with a stout trunk up to 3 ft 3 inches in diameter bearing several erect branches. In overall appearance, it resembles the related saguaro (Carnegiea gigantea), but differs in being more heavily branched and having branching nearer the base of the stem, fewer ribs on the stems, blossoms located lower along the stem, differences in areoles and spination, and spinier fruit.
Its flowers are white, large, nocturnal, and appear along the ribs as opposed to only apices of the stems.
An average mature cardon may reach a height of 30 feet, but individuals as tall as 60 feet are known. It is a slow-growing plant with a lifespan measured in hundreds of years. Most adult cardon have several side branches that may be as massive as the trunk. The resulting tree may attain a weight of 25 tons.
Image: Davepape, Public domain, via Wikimedia Commons
LET734 Argentine Toothpick ( Stetsonia coryne )
Stetsonia coryne grows to a height of 15 to 25 feet tall. It has white flowers. The genus was named to honor Francis Lynde Stetson, a New York attorney and plant lover.
The plant is large, arborescent habit , tree-like reaches a growth height of 15-20 feet up to 35 feet. The trunk is thick and short, with numerous erect or somewhat bent branches form from a trunk. The blue-green shoots, turn greenish-gray with age, usually not jointed and have a diameter of 9 to 10 centimeters. There are 8 to 9 blunt-edged, somewhat notched ribs that are 1 to 1.5 centimeters high. The yellow spines, which later turn black, are straight and stiff. The central spine grows to 2-5 cm long and are thickened at the base., the 7 to 9 spreading marginal spines to 3 centimeters long. There is a single central spine, straight and more robust, which can measure up to 8 cm in length. All are black or yellowish-brown in color, although they eventually turn white with a dark tip.
It flowers from October to April with funnel-shaped flowers that are white and grow up to 15 centimeters in diameter. They open at night and often remain open until the next day. The pericarp is covered with numerous, roof-tile-like, the long corolla tube with scattered scales.
The plant fruits from January to May and its fruit is a fleshy berry 4 cm in diameter ovoid, scaled, edible fruits are green to reddish and have a drooping floral remnant. The broadly oval, shiny blackish-brown seeds are 1.7 millimeters long and 1 millimeter wide. They are humped with a fine wrinkled pattern.
Full sun. Heat tolerant. Little to moderate water, summer. Hardy to 18 F. Branching cactus to 20 feet tall. Origin: Low deserts of Argentina, Bolivia. USDA: 9-11. Good container cacti for many years.
Image:cultivar413, CC BY 2.0 , via Wikimedia Commons
LET735 Octopus Cactus ( Stenocereus alamosensis )
Stenocereus alamosensis consists of many slender, arching stems branched at the base of the cactus that often form an impenetrable thickets that reach up to 30 feet wide. These green, fleshy stems measure about four inches in diameter, and have five to eight spines with either gray or white radial spines running the entire length of the stem. Throughout the spring, the octopus cactus blooms scarlet tubular flowers.
The young plant is a tangle of prostrate, slender stems that root profusely on the lower side. The octopus cactus requires no additional water, as it thrives off of rain fall. It is considered a hardy plant, but S. alamosensis is frost-tender and needs protection in such conditions. For the best growth, the octopus cactus must live in full sun exposure.
USDA: 9b-10. Full sun. Little water. Hardy to 28°F. Thicket of bending stems, up to 10 ft tall. Tubular pinkish red flowers, attracts hummingbirds. Origin: Mexico (Chihuahua and Sonora)
IP286 Blue Candle ( Myrtillocactus geometrizans )
Grows to 12' tall outside, or will remain small in containers, branching; 8" diameter. Edible purple berries. For zones 9b-11 outside. Full sun. Heat tolerant. Moderate water. Origin: Northern central Mexico.
SF148 Texas Prickly Pear ( Opuntia engelmanni )
A shrubby cactus that can reach to about 3 feet tall with much branched, flat, grayish or pale green shoots and yellow flowers, native to the southwestern USA and northern Mexico at higher elevations.
It can take severe drought and hard freezes and is suitable to USDA Zones 6 and above. The fruits are edible and popular for making jelly and jam.
Good container cacti.
D8418 Golden Barrel ( echinocactus )
A striking plant from Mexico Spherical when young becoming
elongegated with age. The green body is covered with heavy
gold-yellow spines. The flowers are a striking color of deep
gold.
3307 Old Man of the Andes ( Oreocereus )
This is a large cacti that can be used as a centerpiece or as a patio plant. It is a stout, upright cactus that covers itself with attractive, long, white woolly hairs. This also makes a great rock garden plant. Will normally stay small in containers, they can reach up to 10 feet tall outside after many years.
Jim's Note: Oreocereus need a minimum temperature of 45° F. Grow them in rich, porous, sandy soil and let their soil dry out between waterings. Repot in the spring, when their roots become cramped. Generally, they should be repotted every other year in order to provide fresh soil. However, this doesn't necessarily mean they'll need larger pots. Fill about a quarter of the pot with broken crocks, gravel, etc. to promote good drainage. Firm the potting soil. After repotting, do not water for a week or more.
D8430 Hedgehog ( echinocereus )
A must for every collection. Small and globular in shape and covered with short curving spines. Flowers profusely, flowers vary in color. It is a very tolerant plant and is a good selection for beginners. Great in small pots and containers.
FB102 Melocactus
Similar to barrel cacti when young but from their crown a large tuft of bristles will emerge. Produces small pink flowers and edible fruits. Excellent inside plant.
CACTUS CARE TIPS FOR SEEDS/PLANTS
PLANTING YOUR SEEDS
With a little patience and
effort, you should have no problem raising beautiful cacti from
the seeds you receive from us. Please remember that the seeds
will sprout over a period of time, so don't be disappointed when
only a few first start to sprout. The others will arrive given
time. Usually most of the seeds will sprout between 3-10
weeks.
Bottom heat will give faster results, but is not an absolute
necessity. If you can provide bottom heat, then by all means do
so. If you cannot, then use shallow containers that can be
covered with glass or plastic. The containers should be large
enough to allow for 2 inches of crushed gravel or sharp sand
(aquarium sand will do fine) to facilitate drainage. On top of
the sand or gravel, you will need to place about 2 inches of
sterilized soil. I recommend a mixture of 1 part sharp sand and 1
part peat humus. It is very important that the soil is
sterilized. Heating soil in an oven at 200 degrees for 15 minutes
is a good way to assure it is properly sterlized.
Soak the soil with water mixed with fungicide. This will prevent
damping off later on. Allow excess water to drain off. Press
seeds lightly into soil and cover with about 1/8 inch of soil.
Cover with glass or plastic and place in warm location. Keep soil
damp but not wet. I suggest misting the surface regularly.
After the seeds have begun to sprout, leave the glass or plastic
in place. Leave on for about two weeks. In the meantime make sure
the container does not receive direct sunlight as this may kill
the plants. When the cover is removed, make sure that the plants
do not receive any strong drafts or sudden temperature changes.
It will take a couple of days for the seedlings to become
hardy.
CARING FOR YOUR PLANTS.
A few tips on caring for
your new plants:
Never use tap water or alkaline water. Rainwater is best but tap
water that has set in an open container for 2 days will be
fine.
Cacti cannot tolerate high alkaline soil. Check your soil for ph
if you have problems with cacti.
Use fungicide mixed in with your water often when watering.
Use very weak solutions of plant food when feeding. Too much
fertilize will distort your plants.
Never expose young seedlings to direct sunlight. They need
bright, diffused sunlight.
The quickest way to kill a cacti is overwatering it. Let soil dry
out before rewatering.
Cacti are succeptable to aphids, mealy bugs, white flies and
spider mites. Treat soil with systemic insecticides and add
paradichlorobenzene crystals to soil if possible.
If a plant show signs of rot due to overwatering, cut out the
affected part immediately. If the top of the plant is cut off,
let it air dry for a few days then repot. Often it will reroot
itself.
Brown scarring is often a sign of too much sunlight. Move plants
to a more protected location.
If possible, let plants spend first winter in original planter
the seeds were sowed in. If overcrowding will not allow this, try
to disturb the roots as little as possible.