Choosing and Caring for Your Poinsettia By Olivia Tracy

Poinsettia Plants (Euphorbia pulcherrima) Photo courtesy of Olivia Tracy

In the first weeks of December, many people buy poinsettia plants (Euphorbia pulcherrima) to decorate their homes for the holiday season. While the vibrant red and pink leaves of the poinsettia are often referred to as “flowers,” they are actually called bracts; the true poinsettia flower sits at the center of those bracts. 

Here are a few tips for selecting healthy poinsettia plants and caring for them in your home. 

• Choose plants with dark green leaves; if the cultivar has lighter or mottled bracts, then the foliage may be lighter as well. Avoid plants with pale green and yellow leaves; this often indicates that the plant has been given too little or too much water. 

• If it’s cold outside (around or below 35 degrees Farenheit), be sure your poinsettia is carefully wrapped before you transport it. Once it’s in your home, remove the plastic sleeve immediately; leaving the plant in the sleeve can damage the bracts. 

• Be sure your poinsettias receive indirect sunlight for at least six hours a day; avoid direct sunlight, which can fade the bracts, and protect your poinsettia from extreme temperatures by not placing it near drafts or heating vents. 

• Water the poinsettia whenever the top of the soil feels dry to the touch. When watering, be sure to either remove foil wrapping or cut a hole in the bottom of the wrapping so that water can drain out of the pot; too much water can suffocate the root system.

For more information about poinsettias, including how to fertilize your plant after the holidays and help your poinsettia re-flower next year, please see the CSU Fact Sheet 7.412, “Poinsettias” http://extension.colostate.edu/topic-areas/yard-garden/poinsettias-7-412/  

Houseplants for Low Light by Olivia Tracy

Snake plant (Sansevieria trifasciata) from http://www.hort.cornell.edu/4hplants/Flowers/SnakePlant.html

As the days shorten in the fall, you might find that your home doesn’t get the same quality of interior light that it gets during the summer months. You may also have a room in your home, or at your workplace, where you’d like to have some greenery, but don’t get a lot of natural sunlight. Not to worry- there are a few houseplant varieties that generally adapt well to low-light conditions and can bring color to those spaces as we head into winter. 

Summer Mystery: Powdery Mildews by Olivia Tracy

Photo courtesy of M. Grabowski, UMN Extension

If you’ve gone out to your peonies and found that they look like someone dusted them with talcum powder, you likely have a case of powdery mildew. Varieties of powdery mildew can affect almost every type of plant (although particular infections are host-specific), and the leafy portions of the plant are typically most affected. The original whitish-gray, powder-like growth will eventually turn brown, and then black, and can ultimately cause leaves or buds to drop off the plant.

Variegated Tulips: Beauty From a Virus By Olivia Tracy

Variegated Tulip (Tulipa), likely “Tulip Yellow Spring Green.” Photo courtesy of Olivia Tracy.

Have you ever seen tulips like these, tulips that look like they’ve been ‘painted’ with multiple colors? Many people love the look of these variegated tulips, and they’ve been popular since the 1600s, when Holland went mad for variegated tulip varieties and tulip speculation (and tulip prices) skyrocketed.¹ While we don’t have this mania today, we can still buy varieties like Rembrandt, Princess Irene, Kaufmanniana and many others that promise beautifully variegated tulips. 

Rosemary “for Remembrance” By Olivia Tracy

Rosemary (Rosmarinus officinalis); photo courtesy of PlantTalk Colorado

During Shakespeare’s time, rosemary (Rosmarinus officinalis) was often associated with memory or remembering; it was given as a sign of friendship, and the early Herballs believed that the scent could “quicken the senses and memorie” (John Gerard, The Herball, Or Generall Historie of Plantes, 1597). These herbals may have been on to something-- recently, scientists have found possible relationships between the scent of rosemary and improved cognition.⁴

Today, rosemary is a welcome presence (and scent) in an indoor winter herb-garden. A Mediterranean plant, rosemary doesn’t tolerate low temperatures well; however, when planted in a container, you can keep it indoors during the winter, and move it outdoors during the warm summer months.² You can buy rosemary plants from a store, or you can start them from seed. (You can also propagate rosemary through cuttings; however, it is best to take cuttings from rosemary in the spring or summer.)³ 

• Plant your rosemary plant in soilless mix (potting soil),² and be sure to allow the soil to dry between watering (rosemary is a fairly drought-tolerant herb).¹ 
• Apply water-soluble fertilizer every few weeks to help the plant thrive in the indoor space.² 
• Like most herbs, rosemary loves sunlight, so be sure to place your rosemary plant in an area that will receive the largest amount of possible sunlight (in a south- or west-facing window).² 

If you’d like more information about rosemary, other herbs, and herb gardening, the following webpages were sources for this post, and are excellent sources to explore: 

¹CMG GardenNotes #731, Herb Gardening http://www.ext.colostate.edu/mg/Gardennotes/731.pdf , 

² PlantTalk 1056- Indoor Herb Garden http://planttalk.colostate.edu/topics/annuals-perennials/1056-indoor-herb-garden/

³If you hope to propagate rosemary or other herbs by cuttings, you may find useful advice in this article by the Missouri State Extension: https://extension2.missouri.edu/g6470 

⁴Recent study exploring the relationship between the scent of rosemary and cognition in schoolchildren: http://www.scirp.org/journal/PaperInformation.aspx?paperID=79934 

Brighten Your Space with Indoor Citrus By Olivia Tracy

Etrog Citron (Citrus medica); photo courtesy of Olivia Tracy

This winter, if you’re hoping to cheer up your indoor space, why not incorporate the bright color and invigorating scent of a citrus tree? While some citrus varieties are too large to grow indoors, there are dwarf cultivars of lime, lemon, orange and tangerine that can grow in containers, including the ancient Etrog Citron (Citrus medica; pictured); sour citrus does particularly well, as it requires less heat to ripen.³ While many nurseries are now closed for the season, you can still mail-order dwarf citrus trees from reputable seed and plant distributors. 

Some Indoor Citrus Varieties Include:^1,2,3 

LIMES: 

Bearss Lime (Citrus latifolia)

Kaffir Lime (Citrus hystrix), grown mostly for the leaves

LEMONS:

Meyer lemon (Citrus x meyeri)

Variegated Pink Lemon (Citrus x limon)

TANGERINES AND ORANGES: 

Mandarin/Satsuma Oranges (Citrus reticulata); actually a tangerine, with fragrant flowers and the familiar ‘orange.’

Calamondin Orange (Citrofortunella mitis), a small, sour orange; often grown as an ornamental.