Ask the Master Gardener: Castor bean plants can be a dramatic addition to a garden

Collecting and planting the seeds from the castor bean plant will allow you to grow additional plants quickly.

Castor bean plant, or castor oil plant, (Ricinus communis) is native to Africa and occasionally grown for medicinal and ornamental purposes in Minnesota. The seeds contain ricin, an incredibly toxic compound which can be deadly if ingested.

Dear Master Gardener: I was given a small plant as a gift last spring. It grew into a gigantic plant with striking leaves and spiky pink seed pods. I've learned it is a castor bean plant. I'd like to collect its seeds and grow more of them next spring. Any suggestions as to how best to do this?

Answer: The castor bean plant with its large, tropical-looking leaves and unusual spiky seed pods is a dramatic addition to the garden. To collect castor bean seeds, clip the dried seed pods from the plant. They are prickly, so gloves are highly suggested. You can either store the seeds in the pod or remove them. To remove them, break open the seed pod and take out the shiny, bean-like, mottled seeds. Store them in an envelope. Don’t bother saving any castor bean pods or seeds that are small -- just keep the larger ones. The seeds remain viable for two to three years. The seeds are extremely poisonous. The toxin in castor bean seeds is ricin -- four seeds can kill an adult. As an aside, the toxin doesn’t occur in pure castor oil, which is sometimes used for medicinal purposes

You can either directly plant the seeds in your garden at the end of May next year, or start them indoors six to eight weeks before the last frost (early to mid-April) then transplant them outdoors. Before you plant the seeds either nick (scarify) or soak them overnight for better germination. Sow the seeds about an inch deep. They should start emerging in one to three weeks. The plants grow quickly, so you may need to repot them into larger pots before transplanting them outside. Grow them in full sun in a protected spot (their huge leaves can get damaged in wind). If you are planting several, plant them about 4 feet apart.

Related: Ask the Master Gardener: Prepare your garden for the coming winter

Dear Master Gardener: I heard that you can grow an avocado tree from an avocado you buy at the grocery store. Is this an easy thing to do?


Answer: Yes, it is easy to grow an avocado tree from an avocado purchased at your local grocery store. If your purpose in growing an avocado tree is to eat the fruit, you will have a long wait, and it may never bear fruit. However, you will have a pretty houseplant.

To turn your grocery store avocado into a houseplant, remove the seed and wash it. Suspend it over a glass or jar filled with water by inserting three or four toothpicks into the avocado seed, making sure the wider end of the seed is in the water, covered about one inch. Keep it in a warm place away from sunlight and keep adding water as needed. You may want to change the water every few weeks. The roots and stem should sprout in two to six weeks. If it doesn’t try another seed. When the stem is 6 to 7 inches tall, cut it back to 3 inches. When the roots are thick and the stem has leaves, plant it in an 8-12-inch diameter pot with good quality potting soil, leaving half the seed exposed. Place the avocado tree in a sunny location and water it lightly and frequently, being careful not to over-water it. If the leaves turn yellow, you may be over-watering the plant; let it dry out for a few days. When the stem is 12 inches tall, cut it back to 6 inches to encourage new shoots to grow.

Related: Ask the Master Gardener: Add a splash of fall color to your yard with shrubberies The Brainerd area supports numerous colorful shrubs that show off the splendor of autumn.

Dear Master Gardener: I saw a Japanese maple tree in a gardening magazine and they look beautiful. Can they be grown here (I live in Pequot Lakes)?

Answer: Some maple species grow very well in this area, but unfortunately the beautiful Japanese maple isn’t one of them. It is hardy to zone 5 (low temperatures of 10 degrees below zero to 20 degrees below zero). Crow Wing County is in USDA hardiness zone 3b, which means plants need to survive cold temperatures to 35 degrees below zero. Black Lace elderberry (Sambucus nigra) could be an alternative to a Japanese maple. Although they are hardier than a Japanese maple, they are a zone 4 (20 degrees below zero to 30 degrees below zero) plant. I have tried growing a Black Lace elderberry twice, trying to get the look of a Japanese maple in my garden, but didn’t have success. I planted them in two different areas, but neither one made it through the winter. If you have a microclimate and/or sheltered location, you could try growing an elderberry. Those who live in town in Brainerd often have better luck with zone 4 plants because it tends to be a little warmer and more sheltered there. Black Lace elderberry is a gorgeous shrub with finely cut deep purple-black foliage and soft pink flower clusters that bloom in early summer. The berries are edible and sometimes used to make syrup or wine. It might be worth a try!

Related: Ask the Master Gardener: The keys to successful planting in shaded areas Gardening in full shade can be a little challenging, but planting perennials can thrive in such conditions.

November Gardening Tips

  • Start new amaryllis bulbs in order to have flowers by holiday time. They take about six to eight weeks to bloom – more if they’re in a cool place. Pot bulbs in containers just a little wider than their diameter. Water thoroughly and set them in a sunny window. When the buds open, move them out of direct sunlight so they last longer.

  • Even though we have snow already, if you didn’t get protection on your fruit or other thin-barked trees, try to get tree guards on or encircle them with hardware cloth, to prevent mice or rabbits from girdling them (killing them) over the winter.

  • Clean and sharpen gardening tools, then wipe them with a light coating of oil to prevent rust. Drain water from hoses and coil them loosely so they don’t kink and crack. Seal bags of fertilizer and keep them off the garage floor so they don’t get damp and hard over winter.

  • Potted chrysanthemums in rich, autumn colors are often sold for Thanksgiving. Choose plants now with some buds just opening, rather than in full bloom. They should last for three to four weeks if kept in a bright location. Most florist mums are not hardy in Minnesota, so enjoy them while they are blooming, then throw them away.

You may get your garden questions answered by calling the new Master Gardener Help Line at 218-824-1068 and leaving a message. A Master Gardener will return your call. Or, emailing me at and I will answer you in the column if space allows.
University of Minnesota Extension Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. Information given in this column is based on university research.
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