Ask the Master Gardener: Steps to care for tropical and citrus plants in winter
Plants such as hibiscus can survive with the right amount of care.
Dear Master Gardener: I bought a hibiscus at the beginning of the summer and had it on my patio. I just brought it in last week before the weather turned cold (and snowed). How do I take care of it over the winter?
Answer: Here are the steps to take to care for your hibiscus (or any tropical plant or citrus tree) you have brought indoors for the winter:
Check for insects. If the plant has spider mites or aphids spray it with insecticidal soap.
Put a systemic insecticide, labeled for indoor plants, in the potting medium to prevent an insect problem over the winter. Follow the instructions on the label.
Hibiscus, like most tropical plants and citrus trees, like as much sunlight as you can provide. A south-facing window is ideal. The more light these plants receive, the happier they will be. If you need to supplement with artificial light, shop lights work just fine. Tropical plants need to be protected from warm and cold drafts. Bursts of hot or cold air can cause yellow or brown foliage.
Don’t be surprised if your plant drops its leaves or buds -- it just needs time to adjust to its new location. Hibiscus in particular will do this in response to the stress of being grown indoors.
Continue to water thoroughly whenever the top few inches of soil start to dry, which is a general rule for most houseplants. Houseplants typically require less water during the winter.
You can prune and shape your hibiscus if it needs it. Don’t prune it after the end of February or you will delay summer blooming.
Wait until March to start fertilizing with a houseplant fertilizer. This is true for all houseplants.
Continue to watch for pests, and water as needed. Enjoy the added greenery and occasional flower.
Answer: It depends on what type of ornamental pepper plant you have. According to the University of Illinois, Iowa State University, and Colorado State University ornamental peppers are edible, but usually only grown for their beautiful foliage and colorful fruits. They are not known for their flavor and could be quite hot. If your ornamental plant is actually a Jerusalem cherry (which are often sold during the holidays) then it is not edible. All parts of the Jerusalem cherry plant contain a toxic alkaloid and are poisonous to humans, cats and dogs.
Answer: Spider mites are not insects, but more closely related to spiders. They are very tiny. Early detection is key to getting rid of them. First, to see if you have them, place a piece of white paper under the branch or stem of the plant and shake it over the paper. If there are tiny specks moving around, they are probably spider mites. If you crush them across the paper in a streaking motion with your finger and green streaks are produced you have the plant-feeding mites that you will want to eradicate. Most spider mites can be eliminated by spraying the plant with a horticultural oil or insecticidal soap. Apply it to the top and underside of the plant’s leaves. They are also effective for controlling aphids, thrips, and whiteflies.
Answer: Hopefully they were on clearance! You have nothing to lose by waiting a few days to see if the snow melts -- and if it does and the ground isn’t frozen -- you might as well plant them. Follow the instructions provided on the bulb package for planting depth. If there are no instructions, the general rule is to plant them two to three times deeper than their diameter. In light, sandy soil (which is common in the Brainerd lakes area) plant them 1 to 2 inches deeper.
Another option is to force some (or all) for winter bloom -- daffodils are one of the easiest bulbs to force. You will need a lot of pots if you are going to force all one hundred -- I’m estimating 25. Please send me a photo if you do it because 100 blooming daffodils in your home this winter would look quite spectacular! Planting can take place any time from now until December, depending on when you want them to bloom.
To force daffodil bulbs, here is what you do:
Partially fill 6- 8-inch pots with potting soil. Place the bulbs on the soil surface. You should be able to get three to five bulbs in each pot. Adjust the soil level until the tops of the bulbs are slightly below the rim of the pot. Fill soil in around the bulbs allowing the tops to stick well above the potting soil. Water thoroughly.
Daffodils must have a cold treatment at temperatures of 40-45 degrees for 13-15 weeks in order to bloom. Longer cold storage will result in taller flowers. Possible places are a refrigerator, heated garage, or basement. During this time, keep them watered and in complete darkness.
At the end of the cold treatment you should see yellow shoots that have emerged. Place the pots in a warmer location (60 degrees is ideal) in direct sunlight. It takes about three to four weeks to flower. When the flowers begin to open, take the plants out of direct sunlight so the flowers last longer. It is not necessary to fertilize. It is usually advised to throw away bulbs that have been forced, but the American Daffodil Society says that daffodils can be placed outdoors as soon as spring arrives and many of them will flower in one to two years.
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 email@example.com 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.