Cactus Care


The ferocactus, barrel-shaped cacti with prominent ribs, are named for their long, heavy, hooked spines. See more pictures of cacti.

Almost everyone knows that a cactus can go a long time between drinks, but there are a number of plants in other families -- crassula, euphorbia, and lily -- that can do the same thing. But, what is a cactus and how do you care for it?

Cactus Image Gallery

Cacti are a type of plant called succulents. They've learned how to compete for survival all over the world.

Cacti from desert areas, like the Mammillaria and Echinocactus, are plump and spiny while those that originally grew in jungle areas are flat or thin and spineless like the Rhipsalis and Schlumbergera.

There are even cacti with leaves. For instance, the Pereskia, when full grown, looks a bit like an orange or grapefruit tree. Other succulents come from a number of families.

The agave, milkweed, lily, and crassula have many members. These plants, with or without spines, all have compact growth habits and lots of character.

This character has caused us to bring them into our homes. In this article, we'll talk about how to care for cactus plants.

Light Requirements of Cactus Plants will help you break the myth that cacti need lots of sunlight. Learn which cactus plants require hours of natural light and which ones can thrive indoors.

Water and Humidity Requirements of Cactus Plants is a great resource to find out just how wet your plants need to be.

Temperature Requirements of Cactus Plants will teach you everything you need to know about the tolerance level of cacti.

Fertilizing Cacti will help you determine whether or not you should fertilize your cactus plants.

Preventing Cacti Pests and Diseases will alert you to what pests and diseases are most harmful to your plant and how to deal with them.

Potting Cactus Plants will teach you how to correctly pot your plant, how to remove a stuck plant from its pot, and how to handle spiny plants.

Propagating Cacti will explain how to successfully propagate, divide, cut, graft, and grow your plant from seeds.

Arranging Cactus Plants is a great resource for learning how to arrange different types of cactus plants.

Putting a cactus near the sunny window is a no-brainer, but what if your view is of a sunless brick wall? Learn about the light requirements of cactus plants in the next section.

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Light Requirements of Cactus Plants

The melocactus is a large ribbed, ball-shaped plant that develops a cap on the top of the plant at maturity.
The melocactus is a large ribbed, ball-shaped plant that develops a cap on the top of the plant at maturity.

Light is essential for cactus plants, as you probably know. Tremendous differences occur in plants, based on their type.

Look at the plant to get an indication as to its origin and its light preferences.

Succulents that have spines need bright light to grow well but they will exist with less. Confined in pots next to a window they may sunburn.

Protect them from concentrated rays of the sun. Succulents without spines do well in bright to filtered light with protection from the very hot sun.

Light and Day Length

Cacti and other succulents do well in 16 hours of fluorescent light mixed with incandescent light in a ratio of 10 watts of fluorescent to one watt of incandescent light.

If you want flowers, you will have to do a little studying on your plants' individual requirements. Some need to be kept cool for a while and others need a good rest with plenty of darkness before they will flower.

Christmas cactus, Schlumbergera bridgesii, for example, should be kept rather dry -- below 60 degrees Fahrenheit and given eight hour days (16 hour nights) to encourage blooming. Set your timer or cover the plant each night with an opaque, black cloth.

When we refer to types of light, we generally refer to "bright," "filtered," and "shady." Here's what those definitions mean:

Bright. This means bright light or full sun with no curtains or blinds between the plant and the window. On the other side of the window, there is no tree, sign, or building to obstruct the light from the outside. In bright light, when you hold your hand a foot over a sheet of paper, you get a clear, sharp shadow.

Filtered. This means sunlight which is diffused by a glass curtain in the window. In filtered light, your hand makes a fuzzy, but distinguishable shadow when held a foot above a sheet of typing paper.

Shady. This means no direct sun or other light, and your hand held a foot over a sheet of paper will produce nothing more than a blob. All plants that tolerate shade need high humidity.

Although cacti are known for surviving in the dry, desert heat, they also need water to flourish. In the next section, learn about the water and humidity requirements of cactus plants.

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Water and Humidity Requirements of Cactus Plants

Although cacti are known for surviving in the dry, desert heat, they also need water to flourish. However, not all cacti and succulents need the same amount of water.

It is important to research the amount of water and humidity your cactus or succulent will need in order for it to have a long, healthy life.

Do a thorough job when watering cacti and other succulents. Think of a cloudburst in the desert. Then let them go a long time until the next drink.

In the winter, many cacti become dormant and watering should be restricted. African succulents often go into dormancy in the summertime; when they are in this state, hold back on the water. Water combined with cold or dormancy spells disaster.

When the plants are actively growing, water them quite frequently and keep them moderately moist. Water and warmth while the plants are growing spells growth.

Cacti and other succulents can tolerate the dry air very well, even though the air in most houses and apartments in winter is drier than that in the deserts.

When we refer to types of watering, we generally refer to "drench and let dry," "moist," and "wet." Here's what those definitions mean:

Drench and Let Dry. Soak the plant thoroughly by submerging the pot in a bucket or sink filled with tepid water. Wait until all the bubbles have stopped coming out. The plant can then dry until its next soaking, which should take place when the surface of the soil is dry to the touch. Most of the plants that prefer drenching and drying have thick roots.

Moist. Keep the soil evenly moist but never soggy or too dry.

Wet. Keep the soil wet at all times.

Although cacti are known for surviving in the dry, desert heat, there are a variety of cacti that can survive outside all year long in Canada and Alaska. In the next section, learn about the temperature requirements of cacti and succulents.

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Temperature Requirements of Cactus Plants

The stapelia can sunburn in the hot summer sun.
The stapelia can sunburn in the hot summer sun.

An environment with the correct temperature and amount of air circulation is essential for cactus and succulent plants to survive, as you probably know. Tremendous differences occur in plants, based on their type.

The plant’s origin will usually give you a good indication of the plant’s temperature and air circulation preferences.

As long as they are dry, most succulents are very tolerant. They can take temperatures from 45°F to 85°F without complaint as long as they are dry.

There are even cacti that survive outside all year long in Canada and Alaska. Succulents don't care for stuffy environments, especially when they are wet.

Keep plants well separated and give them plenty of air. Night temperatures below 65°F and less than 12 hours of light are required to encourage most succulents into bloom.

Most plants prefer a distinct difference between their night and day temperatures; with the night temperature being more important to a plant's growth.

When we refer to types of temperature and air, we generally refer to "cold," "cool," "house," "dry," and "circulating." Here's what those definitions mean:

Cold. Night temperatures of 40° to 45°F.

Cool. Night temperatures of 50° to 55°F. A good many of the old-fashioned favorites are in this category. When these plants look listless and not quite bright, they probably had a bad night.

House. Night temperatures of 60° to 65°F. These are what used to be called stovehouse or hothouse plants.

Dry. The typical modern house, apartment, or office contains half the percentage of moisture that's found in the Sahara.

Circulating. Plants which need fresh air and good ventilation.

Actively growing plants can benefit occasionally from a fertilizer treatment, and cacti and succulents are no exception. In the next section, learn about fertilizing requirements of cactus and succulent plants.

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Fertilizing Cactus Plants

Rebutias are good indoor bloomers that prefer heavy soil with excellent drainage.
Rebutias are good indoor bloomers that prefer heavy soil with excellent drainage.

Old and well-established plants that are actively growing can benefit occasionally from a dilute liquid fertilizer -- cactus and succulent plants are no exception.

Since each plant is different, research should be done before fertilizing your plant. The plant’s origin will usually give you a good indication of its fertilizing requirements.

For example, succulents are accustomed to having it tough. If you aren't sure they can use help, don't fertilize.

If you are growing your succulents warm and wet, they will need more fertilizer, but use restraint.

Occasionally, cacti and succulents may become afflicted by a variety of pests or diseases. In the next section, learn about what types of pests and diseases can attack your plant and how to deal with these problems.

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Preventing Cacti Pests and Diseases

Rot is a serious disease that can infect succulent plants such as the echeveria.
Rot is a serious disease that can infect succulent plants such as the echeveria.

Occasionally, cacti and succulents may become afflicted by a variety of pests or diseases.

This section will help you learn about what types of pests and diseases can attack your plant and how to deal with these problems.

After people, the most frequent pests are mealybugs, nematodes and scale. If you get nematodes, remove all the soil from the roots and repot using pasteurized soil or mix. For mealybugs and scale, depending on the number of spines the plant has, a good scrub with an old toothbrush and warm soapy water can do wonders.

If you are using chemical sprays, read the label very carefully since some popular sprays, such as malathion, can injure succulents as much as the pest.

The most serious diseases are rots. Rots can be aggravated by improper watering, forcing growth during periods of dormancy, and wounding plants when repotting.

Sometimes the plant can be saved by cutting out and removing material one-half inch beyond the area that looks decayed. The wound should be washed with a solution of one part household bleach and nine parts water.

The plant should be kept in intensive care in an area of low humidity until it recovers. Unless it is special, get rid of it.

Choosing the correct size pot and type of soil are essential for the survival of your cactus or succulent plant. The next section will teach you everything you need to know about correctly potting your cactus or succulent plant.

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Potting Cactus Plants

Pot cacti and other succulents in containers that are as small as possible.
Pot cacti and other succulents in containers that are as small as possible.

Choosing the correct size pot and type of soil are essential for the survival of your cactus or succulent plant.

This section will teach you everything you need to know about correctly potting your cactus or succulent plant including choosing the correct pot size and soil type, how to pot or repot your plant, how to knock out a plant, and how to handle spiny plants.

Cacti and other succulents can be kept in a dish garden when small. The clay trays often used for bonsai are very good for a start.

When the plants get too big they can be transplanted into their own pots. If you keep the plants dry they will stay the same size whether the temperature is 45°F or 85°F. If you water the plants when the temperature is low or while they are dormant they will rot.

Don't overpot. Overpotting often leads to rotting of roots. If the plant is top heavy, put the smaller pot inside a larger pot and fill the space between the two with gravel. This will give the plant a heavy enough base without running the risk of rot.

Pot Size

Pot cacti and other succulents in containers that are as small as possible. For cacti, use a pot just large enough to fit the plant. For other succulents, use a pot just slightly larger than the root ball.

For some plants, the holes in the bottom of the pot do not provide enough drainage. Use a hammer and a screwdriver to make the hole larger in a clay pot. Use a hot knife or a hot ice pick for a plastic pot.

In either case, be careful not to break the pot or burn yourself. If you do break the clay pot, don't throw it away -- you can use the pieces for your next planting project.

Soil

Excellent drainage is more important than the potting material. The soil should be porous and should be spread over a deep layer of gravel or broken bricks. The spineless succulents appreciate more humus (organic matter) in their potting mix.

When we refer to types of soil, we generally refer to "heavy," "organic," and "light." Here's what those definitions mean:

Heavy. This is made of good garden soil, clay, or loam with about one-third humus. When good drainage is required, it should contain about one-third washed builder's sand or perlite.

Organic. This is soil rich in humus, leaf mold (disintegrated leaves), or some other organic material. Coarse builder's sand or perlite will improve the drainage.

Light. This means open-textured material with excellent drainage that can be kept moist but never wet. It is good for plants that in nature spend their time in trees.

How to Pot

1. Select a pot that is not too large.

2. Put sufficient drainage material in the bottom.

3. Fill it about one-third full with your potting material.

4. Test the plant for size (make sure that the plant won't be too far down in the pot nor too high above the top of the pot). Center the plant unless it's the kind that likes to travel in a horizontal direction, in which case it should be put at one edge.

5. Now, gently holding the plant where you would like it to stay, fill all the spaces between the plant and the pot with your potting medium.

6. Press the soil gently down around the roots and shake the pot so the soil will settle. If there isn't enough soil or if the soil packs down, add some more. You pack the soil more tightly around old plants than around seedlings. Leave space between the top of the medium and the top of the pot so you will have room for water.

7. Water the plant.

Repotting

With a plant that is already in a pot, the procedure is pretty much the same except that you have to start by removing the plant from pot number one.

Sometimes the plant will slip out easily; but other times it's more of a problem. If the plant will not come out of the pot easily, do not yank on it. It may be better to break the container than to bruise the plant or break off its top.

How to Knock Out a Plant

If the plant is stuck in its pot, first tap the pot gently on a hard surface such as wood or concrete, and see if you can wriggle the plant out.

If that doesn't work, take a knife and gently slip it around the inside of the pot to see if the plant will now come out.

If that doesn't work, and the pot is clay, take your hammer and give the pot several sharp, controlled blows to break the pot without damaging the plant.

If the pot is plastic, use a sharp knife to cut away the pot.

When the plant is out of the pot, remove some of the soil around the root ball. If the roots look overgrown, prune some of them away.

In some plants where the roots get very, very thick, you can take a knife and just cut off the outside of the root ball including the roots. This root pruning can also be used if you want to keep your plant in the same size pot.

By pruning away some of the roots and then taking off some of the top you can keep your plant "growing on" in the same pot for years.

How to Handle Spiny Plants

Use a newspaper folded into a narrow band to handle spiny plants. Wrap the band around the plant like a belt or harness. Use a fresh band for every plant.

Gloves are not satisfactory since the large spines stab right through and the small spines break off in the glove, making the gloves uncomfortable to handle.

Cacti and other succulents are actually rather easy to propagate. In the next section, learn everything you need to know in order to propagate your plants successfully.

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Propagating Cactus Plants

There are several stages in propagating succulents.
There are several stages in propagating succulents.

You can easily reproduce your cacti and succulent collection through the process of propagation.

There are a variety of ways to propagate your plant, including division, cutting, starting from seeds, and grafting.

The best method of propagating depends on your plant type. This section will explain the different types of propagation.

Cacti and other succulents are easy to propagate. Any encouragement you can give them will start new growth. Remember that they are accustomed to growing on the dry side and too much water or humidity will cause them to rot.

For successful propagation of any kind you will need to:

  • Develop mechanical and technical skills. Train the hand and eye. Many times the head will know how, but the hand can't do it. Skills improve with practice, and fortunately these plants are quite tolerant.
  • Know the plants' structures and how they grow. You can learn this by working with plants -- let them teach you -- or you can read, take formal courses, or a combination of these. If you understand how plants grow, you will have an easier time propagating them and be better able to cope with the unexpected.
  • Know the different kinds of plants and the methods by which they can be propagated. The form of propagation used depends on the plant and your circumstances.

Division

Division is the easiest form of multiplication. It is not only easy on you but also on the plant. Division is ideal when you want only a few plants, or you can use it when the plant starts crowding in on itself.

Preparing the root ball for division. Preparing the root ball for division.
Preparing the root ball for division.

Division is not an extreme form of reproduction. Done gently, it's an operation that is only slightly more traumatic than transplanting.

There is trauma, since the root ball is being separated and a part rather than the whole plant is being potted up; but you have roots, a stem, and leaves (if not the leaves, at least the shoots to produce them). All you need to do is encourage each part to keep on growing and protect it until it gets over the effects of the separation.

Some plants divide easily while others require the eye of a diamond cutter to make the most of the possibilities.

Division of indoor plants can take place at any time, but it is especially successful from the plant's point of view if done during the winter when the plant is resting -- indoor gardeners are less busy then, too.

Dividing plants in the winter is frustrating from the indoor gardener's point of view because the plants will just sit there and do nothing until it is time for them to come out of their dormancy and start growing with enthusiasm.

Many succulents, especially those with thick mats of sprawling growth, can be divided very easily. They do very well, particularly if the division takes place at the beginning of their growing season.

What You Will Need

Before beginning to divide a plant, collect everything you will need:

  • The plant to be operated on.
  • Newspapers.
  • Bucket of warm water.
  • Clean pots.
  • Fresh, clean soil.
  • Drainage aids.
  • Sterile knife.
  • Plenty of time.

How to Divide Plants

1. Spread the newspapers out carefully. Often the hardest part of dividing a plant is cleaning up the mess afterwards.

2. Remove the plant from its pot. Do this gently: break the pot if necessary.

3. Decide how many plants the division is to produce.

4. Separate the root ball gently. If the roots are damaged or torn off, you will have a large cutting rather than a plant division and growth will be slowed. At times, a clean sharp knife or a hatchet is necessary to divide the root ball with the least amount of bruising.

A clean cut is better than a torn and mangled mess caused by pulling and yanking. If you are not sure how the plant is structured under the soil line, put the root ball into a bucket of warm water and gently tease the parts of the plant apart.

There will be some damage to some of the roots, but you will be able to see where the main divisions are. If you are gentle and repot carefully this can be a useful method, especially when working with plants that have become extremely rootbound.

5. Be sure that each division has roots, a stem, and leaves (or shoots), and pot it in a clean, proper-sized pot with good drainage.

Good drainage is very important because the roots have been disturbed and damaged roots are more susceptible to rot.

6. Use fresh, sterile, or at least uninhabited soil. Unless there is a good reason for doing otherwise, place the division in the center of the pot.

7. Plant each division as deep as it was growing before. Press the soil firmly around the plant and water with warm water. Roll up all the debris in the newspaper and clean the operating area.

Put the separated plants in a protected location (out of full sun and drafts) for a few days. In a relatively short time the plants will have adjusted themselves to their new conditions and they will be full-fledged members of your collection or ready to join someone else's indoor garden.

Cuttings

Most succulents root easily from a piece of the plant or from leaves. It is important to let the piece dry out a bit before planting.

Removing leaves to prepare for repotting Removing leaves to prepare for repotting
Removing leaves to prepare for repotting

Fleshy leaves taken off of succulents can be put where they are warm and dry, and they will start sending out roots. That is the time to pot them up. High humidity is not necessary and possibly harmful, but bottom heat is a big help.

In propagating plants by cuttings, a piece of root, stem, or leaf is taken from the plant, kept under favorable conditions, and encouraged to grow. This produces a new plant which is usually, but not always, identical to the original (a variegated Sansevieria cutting will grow plain green).

Stages of growth from leaf to plant Stages of growth from leaf to plant
Stages of growth from leaf to plant

For plants that can be easily propagated this way, there are a number of advantages. It is inexpensive, relatively fast, and doesn't require a lot of know-how except on the part of the plant.

Home is not always the ideal place to propagate plants, but with some plants the percentage of success is so great that one keeps wanting to start more.

For succulent leaf cuttings such as hens and chickens, burro tails, etc., choose mature leaves that are not in the process of dying. If you remove them with a sideways pull there is less chance of damage to the plant and a better chance that there will be a tiny piece of stem attached (having a bit of stem attached often means that you will get a new plant and not just a well-rooted leaf).

Once the leaf has been removed, you can lay it on some potting soil or mix, or put it in a cardboard box on top of the refrigerator or any other convenient place. In either case, don't water until the roots appear.

After the roots and young plant start showing, the mix can be kept moist. (Pot up the ones you had in the box over the refrigerator when the roots and new plant appear.) The leaves may rot if you water them before this. When the new plantlets start growing, put them in a brighter light.

New plants from old leaves New plants from old leaves
New plants from old leaves

For Sansevieria cuttings, take a leaf and cut it into sections three to four inches long. Mark the top of each section by cutting a small notch out of the top. Plant the notch side up.

From Seed

Starting plants from seeds can be especially gratifying. The greatest satisfaction comes from growing plants from seed you have hybridized yourself.

Each seed is a combination of the heredity characteristics of its parents. For this reason plants grown from seeds can vary tremendously. Many succulents grow very easily from seed if the seed is fresh, but they may take a long time to germinate.

Also, since succulents are very cautious plants, they may germinate only a few seeds at a time. Some seeds start germinating in two days and others may take two years.

Stages in propagating cacti from seeds Stages in propagating cacti from seeds
Stages in propagating cacti from seeds

Seeds vary considerably in terms of their longevity and viability; many may not have enough vitality to survive beyond germination.

Start seeds in a well drained, sterile mix. Water sparingly but do not allow the seedlings to dry out. Seeds can not germinate until moisture has penetrated the hard seed coat. The taking up of moisture and swelling is a physical thing that may happen even with dead seed.

Because of the problems of seeds dying in the soil or seedlings dying just after they germinate, it is usually best to start seedlings in an artificial mix.

Grafting

Grafting is used:

  • To speed up the propagation of known varieties.
  • To provide plants with a stronger root system. Many attractive plants grow faster or do not rot as easily if they are grown on plain but sturdy roots.
  • To maintain "sports" or monsters that would not be able to survive on their own, such as a brightly colored cactus that contains no chlorophyll and is unable to feed itself.

Grafting can also be used to produce a shape or effect that would not have been possible with one plant alone. Dwarfed plants can be produced by using a dwarfing root stock or by inserting a dwarfing section in a stem.

Weeping, tree-like effects can be produced by grafting vining or sprawling plants on top of a tall, upright base.

The principles are simple but success takes a keen eye, a steady hand, and lots of practice. Failure is reduced by working quickly and keeping the plant parts, tools (knives or razor blades), and hands as aseptic (clean) as possible.

Grafting is done with compatible plants. Compatibility generally, but not always, means plants in the same species, genus, or family -- plants that are somewhat similar in structure.

Since the plants are the final judge of compatibility, grafting is very often a trial and error process -- with the possibilities of some exciting surprises.

If the diameter of one piece to be grafted is larger than the other, you will have to move the two pieces around so that as many of their actively growing cells as possible are in contact.

The easiest graft to make is a flat graft where both the stock (the part with the roots) and the scion (the part to be added) are the same size and their vascular bundles (tubes that provide support and conduct water and nutrients) match.

A cleft or wedge graft is used when the scion is very narrow or flat. A one-inch slit or wedge is cut into the top of the stock, the scion is trimmed on both sides, and is inserted into the split.

A side graft is sometimes used. In a side graft, a slanting or diagonal cut is made on both the stock and scion. This cut often produces more surface area and a better chance for the graft to take.

When grafting cacti and other succulents, lightweight rubber bands can be used to keep the pieces together, or large spines can be used to pin them on.

Grafting is more successful when the plants are in their active growing period -- usually in the spring through the fall. It is important that the stock plant is in good health and not neglected while the graft is taking.

After grafting, keep the plants in a shaded spot for a while to keep the cuts from drying too quickly.

Keep water off the cuts to help guard against disease.

Keep the contact firm between the stock and scion, and do not remove the rubber bands or spines until a month after the graft appears to have taken.

In grafting, practice makes perfect. For greater success, as well as better looking results, keep your plants, tools, and fingers hospital clean.

As your indoor cacti or succulent garden grows, you might want to think about how to arrange your plants so they flourish. In the next section, learn everything you need to know about how to successfully arrange your plants.

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Arranging Cacti

Torch cacti (cereus peruvianus) can grow quite large -- arrange them in an area with plenty of space.
Torch cacti (cereus peruvianus) can grow quite large -- arrange them in an area with plenty of space.

As your cactus or succulent collection grows, you'll have to give some thought to arranging your plants. Since light is important, window space should be evaluated carefully and used to its best potential.

Many people find that it's easier to take care of plants if they are all kept in one location rather than spread all about; they also complement each other if they are placed together.

In a small window, one or two large cactus plants or a number of small ones neatly arranged look better than several large ones stuck together.

If you have windows coming together at the corner of a room, or if you have windows on one side of a corner and can put a mirror on the other side, you will be able to arrange a space that can display an even greater number of smaller plants.

Place small tables next to the windowsill to create a desert scene while keeping plants out from underfoot. For example, a well-grown century plant is very attractive but quite dangerous unless it is completely out of traffic lanes.

For additional cactus spaces, one-fourth-inch plate-glass shelves, attached across the front of the windows, can be both attractive and efficient.

Glass shelves work well for plants that are not top-heavy and are stable. If the plants have a tendency to tip or vine, then a solution might be to put them in an indoor window box.

Another option for arranging cacti is to hang the plants. Make sure that the hook or bracket, and the way in which it is attached will support not only the pot but also the weight of the plant, the soil, and the water.

Think about the hangers, as well. Hangers of cord or leather may not last as long as wire or nylon. To avoid a messy accident, reinforce cord and leather hangers with transparent nylon filament or lightweight chain.

When deciding on a height, be sure you don't hang the pot so high that the cactus does not get enough window light or becomes difficult to water.

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