Ricinus

( RISS - in - uss )

At-A-Glance Information

Commonly known as Castor Bean, this genus of evergreen shrubs includes just one species, Ricinus communis, which needs full sun and little to moderate water to perform well in the garden. These plants are known for their bold foliage and are native to tropical East Africa (Eritrea, Ethiopia), the southeastern Mediterranean, and India. They can quickly reach 6 to 15 feet tall and wide in a single growing season, and become woody and tree-like in mild-winter areas over the years. Summertime flowers are inconspicuous and white, blooming on stalks in clusters and followed by prickly seed pods. Grow these plants as striking architectural accents or focal points or as a quick-growing privacy screen. They can also be used in large-scale mass plantings for high visual impact. Take care when planting this species in your yard, as the seeds are extremely toxic to humans and animals if ingested and plant parts can cause skin irritation if touched. Ensure that children and pets have no access to this plant or any of its parts.

Ricinus Species and Varietals

Ricinus is a genus in the plant family Euphorbiaceae and includes just one species. The plants in this genus are related to those in Manihot (Cassava), Euphorbia, and Acalypha (Copperleaf). Castor Bean grows well in USDA hardiness zones 9-11 as a perennial, or in any zone as an annual. To find your zone, click here: Zone Map. Ricinus communis is considered invasive in mild, tropical and subtropical regions around the world, including the southern and central United States, Mexico, Hawai'i, South Africa, and Australia. The following plants are all cultivars of Ricinus communis, bred for their size, flower color, leaf characteristics, or resiliencies.

'Carmencita Bright Red'
Dark bronze foliage with red stems and bright red seed pods to 5-6 feet tall.

'Carmencita Pink'
Pink-red stems and dusty pink seed pods.

'Carmencita Rose'
Blue-green leaves, soft peach colored seed pods.

'Gibsonii'
Compact to 4-5 feet tall, with dark red-tinged leaves and pinkish pods.

'Impala'
To 4 feet tall with rich red-purple foliage and stems.

'New Zealand Purple'
Deep red-purple foliage on a little-branching upright plant.

'Red Spire'
7-10 feet tall with red stems, bronze leaves, red pods.

'Zanzibarensis'
To 7-10 feet tall with massive green leaves with white midribs.

Caring for Ricinus

Take care when planting this species in your yard, as the seeds are extremely toxic to humans and animals if ingested and plant parts can cause skin irritation if touched. Ensure that children and pets have no access to this plant or any of its parts. Wear protective gear when pruning and handling seeds and foliage. Plant your Ricinus plant in full sun (at least 6-8 hours of sun per day). Ensure that soil is well-draining, rich in nutrients, and has a pH of between 6.0 and 7.3 (slightly acidic to neutral). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. When mature, provide regular moisture, keeping soil consistently moist but not waterlogged.

Fertilize Ricinus plants yearly in early springtime with an application of 2 inches of compost. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. Pruning is simple; remove any damaged, diseased, or dead foliage at any time during the growing season, and remove spent flower spikes to neaten up the appearance of plants and encourage more flowers to form. Prune early on to maintain shape and encourage a bushy growth; when left to their own devices, these shrubs can grow to be quite tall and leggy. Provide protection from frost conditions by either digging up roots before cool weather arrives or growing Ricinus in containers that can be brought into a sheltered location over winter. These perennial plants can be expected to survive for 2 to 5 or more years in the garden before needing to be replaced.

Caring for Ricinus in Containers
Ricinus plants can be grown in containers, which allows gardeners in cooler growing zones to cultivate these tropical plants. Choose a container that is at least a few inches wider and deeper than the nursery pot or root ball. At full size, Ricinus appreciate a container that is at least 15 to 20 gallons (18 to 24 inches in diameter). Choose a heavy material for the container, as these plants can grow to be very tall and tend to be top-heavy in windy conditions. Ensure that the pot has adequate drainage holes on the bottom to allow for excess water to flow away. Fill with a well-draining potting mix amended with organic material and perlite, and top with a layer of mulch to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water regularly as the plant establishes itself in its new home. Once established, waterings can be lessened. Berberis plants grown in containers will need more frequent irrigation than those grown in the ground. As a general rule of thumb, water whenever the top few inches of soil feels dry to the touch. Prune to remove dead, damaged, or diseased foliage at any time during the growing season. Every few years, check the bottom of the pot to ensure that the plant is not outgrowing its root space. If roots are growing through the drainage holes in the bottom of the container, it is a good indication that it needs to be potted up; choose a slightly larger container and repot.

Propagation

Ricinus can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your shrub, follow the instructions below:

Propagating Ricinus by Cutting

Gather your materials. You'll need protective gear, a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Ricinus by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need protective gear, a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed pods contain the seeds, and are left behind after flowers have faded. Remove them from the shrub and place them in a paper bag. Once you've collected all of your seeds, you'll need to scarify them by rubbing them against an abrasive surface or nicking them with a knife. Place your seeds in cold water, and leave them there overnight. In the morning, lay them out to dry.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Problems and Pests

Ricinus communis plants are considered invasive in some regions; see the species descriptions above for more information. Check with local authorities before planting. Castor Bean shrubs are susceptible to the following issues, but they are known to be generally hardy, disease-resistant shrubs.