Growing Succulent Plants
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Our staff is often asked about plants available for landscaping -- in particular Australian landscape plants. Director of Horticulture Steve Carter suggests the following two links below should be helpful for anyone seeing Australian landscape plants (the first link), and also landscape plants in general.
Soil For Succulent Plants
Soil should be loose and friable. It should drain well. Bacterial and other microorganisms thrive in water-logged soil. When infection begins in a root, the plant may or may not be able to wall off the rot and infection.
Roots need oxygen in air to live, green plants can produce sugar from air and water. This process, termed photosynthesis, requires sunlight or at least some light source. Plant sugars, thus formed, are the food, not only for fueling plant growth, but for sustaining animal life as well.e. You may actually drown roots of succulents by putting them into clay or other compactable soil which can become water-logged. A standard mixture of 1/3 loam, 1/3 sand and 1/3 peat-moss is alright for most succulents. The addition of horticultural perlite (heat-expanded), as another equal part, allows better drainage and aeration. Expanded perlite is shot through with tiny holes which hold air. Commercial vermiculite may also be used as a soil additive. It traps soil moisture, minerals and air in acceptable proportions for succulents.Expensive Soil Mix for Young or Difficult Plants
- 1 part loam or good black soil
- 1part sand (not from salt-water beach)
- 1 part peat-moss or composted bark
- 1 part perlite
- 1 part vermiculite
- + liquid nutrients as needed
A quite acceptable substitute for peat-moss can be made by mixing compost, sawmill shavings and horse-manure. A substitute for loam soil can be made by mixing two parts of silt to one part desert soil and one part vermiculite. Use a cement-mixer.Cheaper Soil Mix for Outdoor Beds
- 2 parts river silt
- 1 part desert soil (may contain clay)
- 1 part vermiculite
- 4 parts sand
- 1 part homemade compost
- 1 part commercial Arizona Composted Bark
- 1 part sawmill shavings
- 1 part horse-manure
Succulents should always be placed in Pots should be chosen carefully to fit the plants. Never over-pot. Over-potting refers to placing a small plant in a large pot. The large pot tends to dry out slower than a small one. This may allow the plant to become infected by organisms that breed in moist soil. Soil in a container dries out partly because the plant uses the water.the smallest container that is consistent with their needs. Ideally, the soil should completely dry out in about a week's time. Clay pots dry out quicker than plastic ones. They also allow fresh air to diffuse into the root zone. Soil remains somewhat cooler in clay pots due both to insulation and evaporation through the clay.
More rapid growth of succulents can occur in plastic pots due to the root temperature differential. Better aeration can be achieved by adding perlite to plastic pots than by using clay pots alone. Plastic pots require much less labor in the form of watering. Some succulents which are difficult to grow do best in clay pots with abundant perlite and sterilized soil.Watering
Most cacti and other succulents thrive with ample intermittent watering. The top one-half inch of soil should be completely dry before rewatering.
Although succulents will tolerate periodic drought, most need ample periodic rain or artificial watering. Most cacti in Arizona grow in microhabitats that receive periodic but ample seepage or run-off following rains. Cacti are more abundant in areas of Arizona having 18 inches of rain per year than in areas having 8 inches! Many cacti of Mexico grow in areas having 50 inches of rainfall annually but which also have periodic drought.
You will find that you can control the growth of succulents by varying their water supply.Shade or Sunlight?
Many cacti or other succulents ordinarily grow in shade. If these are placed in the sun, the epidermis (skin) may actually sunburn. Infection and rot may then set in, resulting in death of the plant.
The giant Saguaro cactus of Arizona requires a nurse-plant when young. Many cacti will tolerate direct sun if broken into it gradually. Cacti tolerate direct sun better when their cells are turgid due to ample water. Plants under glass or in a window are less apt to sunburn because glass absorbs ultraviolet radiation. Fiberglass, on the other hand, used in modern greenhouses, allows ultraviolet radiation to pass through. Colorful pigmentation in leaves or stems of succulents is often enhanced by this radiation.Temperature
Most cacti grow well at 80-100 degrees F. Man leaf-succulents, particularly those in the Crassulaceae do better at 65-85 degrees F. The majority of cacti and succulents can tolerate little or no frost in the winter. Some Species, however, resist freezing because high concentrations of sugar in cell-sap act as antifreeze.Growth
Growth occurs in response to favorable temperature, sunlight or shade, water and nutrients. New growth at the top of a stem is usually different in color and is often shiny or new looking. A real reward can come from observing changes in growth which come as a response to changes a person may make in the habitat of the plant. Application of a fertilizer that is high in nitrogen usually results in vegetative growth in contrast to flowering.Fertilization
Dry chemical field fertilizers may be added to soil in small quantities before planting. It is usually better, however, to add a small amount of liquid fertilizer to the water given succulents in normal watering. Liquid 13-6-6 mixtures sold for house plants are suitable for most succulents.Flowering and Dormancy in the Life Cycle
Most succulents flower once a year when mature. The exact date is determined by photo-period (daylength). Plants given high amounts of nitrogen fail to flower. Vitamin B1 and fertilizers high in phosphorous and potassium stimulate flowering.
Many succulents go dormant once a year. Stapelia is dormant in the winter, while ice-plants are dormant in the summer. Truly tropical succulents may never become dormant if the temperature remains favorable.Propagation
Most succulents grow readily from seeds, but fungicides must be used to prevent damping-off. The really thrilling methods of propagation are vegetative. Space here allows reciting only a few commoner types.
Many leaf-succculents with semi-succulent stems (Kalanchoe, Sedum, Ide-plants, etc.) can be clipped a few internodes down from the stem apex; the resulting cutting can be thrust directly into soil which is on the dry side. Roots will usually grow in about two weeks; the new plant will be vigorous if it has been occasionally watered.
Cuttings from highly succulent stems such as cacti or Stapelia should be set aside for two weeks so that the cut surface can callous over before planting. Callousing and rooting in difficult material is enhanced by painting the cut surface with a wet mixture of equal parts of sulphur, rooting hormone powder and powdered fungicide such as Captan. Difficult cuttings to root should be given sterilized soil mixed with 1/2 perlite. Such cuttings can be given light watering while rooting if they were properly calloused. Some cacti will root in absolutely dry soil.
Cuttings of Euphorbiaceae root best under intermittent mist created by misting nozzles controlled by a time clock.
Many members of Crassulaceae form new plants from margins of leaf cuttings.Grafting
Most succulents can be grafted onto plants of their same family. Cactus mutants which lack chlorophyll are preserved by grafting onto normal cacti.Re-Potting
Re-pot when roots form a ball filling the pot. Check by holding the pot upside down (with fingers on either side of the plant to avoid spills) and tapping it against the side of a table. The pot should lift off of the root-ball. Re-pot to only a slightly larger pot. Make certain that the soil level remains the same in the new pot.Insects
Most insects can be controlled by spraying with malathion which has been mixed with a spreader-activator. This can be rubbed with an old toothbrush onto scale or mealy bugs. Malathion is injurious to Crassula.
The Desert Legume Program (DELEP)
The Taylor Family Desert Legume Demonstration Garden at the Arboretum is just one of DELEP's significant accomplishments. Read more about the DELEP program