Day length is increasing and the sunlight is more intense. Houseplants will begin to show signs of new growth. It is time to start fertilizing your indoor plants.
Leaf yellowing and leaf drop from houseplants can be a result of low light conditions combined with overwatering. Spider mites are another possible cause.
Spring bulbs can still be planted if the ground is not frozen. Inspect the bulbs and plant only the solid, healthy ones as bulbs can deteriorate when stored. They may still bloom this year but will not be as vigorous. Do not cut back the green foliage that emerges, let it die back naturally.
Keep garden beds covered with shredded leaves, straw, or bark mulch to minimize the risk of soil erosion and nutrient run-off.
The Maryland Lawn Fertilizer Law prohibits anyone from using fertilizer products to melt ice and snow on steps, sidewalks or driveways.
Helenium autumnale. Photo: Beverly Turner, Jackson Minnesota, Bugwood.org
Helen’s flower is an underdog when it comes to native plants. It is not as well known or as popular as butterfly milkweed, bee balm, or black-eyed Susans — but perhaps it’s time for its day in the sun. It makes a nice addition to a pollinator garden.
Helenium autumnale is the species name of this North American native perennial plant. It goes by the (somewhat unfortunate) name of “common sneezeweed” because dried parts of the plant were formerly used for making snuff to induce sneezing. As an ornamental garden plant, it is not known to prompt sneezes from pollen dispersal (it relies on insects for pollination) and I prefer to address it by its lovelier common name, Helen’s flower… or just plain Helenium.
Wild Helenium autumnale boasts cheerful yellow button-like flowers tended by a skirt of turned-down petals in late summer to fall. Its natural habitat in Maryland includes swamps and moist riverbanks, so in your garden, it will like a location where it has some regular soil moisture. It can grow in full sun or partial shade and stretches in height from 2 to 5 feet tall. The flowers support a variety of pollinators such as bees, wasps, syrphid flies, butterflies, and beetles.
A wide variety of cultivars of Helenium are now available. They range in color from bright canary yellow to orange and crimson and various combinations in between. Many of the cultivars tolerate drier soil and have a more compact habit.
Mt. Cuba Center in Delaware conducted field trials of 44 Helenium species and cultivars from 2017 to 2019. They evaluated plants for their habit, vigor, disease resistance, floral display, and pollinator visits.
Helenium flowers in a garden, “The warm glow of early Autumn” by hehaden, Flickr
Given the high interest in pollinator gardens right now, I was curious about their observations of pollinator visits in particular.
The native Helenium autumnale had the most observed pollinator visits (162), while the cultivar H. ‘Zimbelstern’ came in second (151). Both of these had excellent powdery mildew resistance as well. Other cultivars such as Helenium autumnale ‘Can Can’ and H. ‘Tijuana Brass’ also had excellent ratings for these two characteristics. The best performers in the study overall (considering all the characteristics evaluated) were ‘Kanaria’, ‘Zimbelstern’, and ‘Can Can.’
The native Helenium autumnale had the most observed pollinator visits (162), while the cultivar H. ‘Zimbelstern’ came in second (151).
If you plan to start (or add to) a pollinator garden this spring, do consider adding Helen’s flower if you have a moist site in full sun or partial shade. Mt. Cuba’s report provides good information on plant care, including staking and pruning tips and recommendations for managing the two most common diseases — powdery mildew and aster yellows.
Visit the Home & Garden Information Center website for additional resources on native plants and gardening for pollinators.
By Christa K. Carignan, Coordinator, Digital Horticulture Education, University of Maryland Extension Home & Garden Information Center. Read additional posts by Christa.
Q: Many years ago, I purchased a Kaffir Lily (Clivia miniata) at the Philadelphia Flower Show and it has special meaning to me. Recently, the bottom leaves are turning yellow. What is causing this and what should I do? Also, sometimes it does not bloom well. Is it true that they need a rest period?
Answer: It is normal for the older leaves to turn yellow and eventually shrivel as the plant ages. Prune off the affected leaves. The rest of the leaves should be green, strappy, and healthy. Yellowing of younger leaves can indicate overwatering: a more-serious symptom. The potting mixture should dry out slightly between waterings when it is actively growing and completely dry out during the rest period.
Clivias do need a dormant period to help with blooming. Starting in late fall or early winter, withhold water and fertilizer and move the plant to a cooler area where temperatures are in the 40–50° F range. Keep it there for about 6–8 weeks, then move it back to a sunny location and begin to water again. You will soon see some
new growth and a flower stalk. At this point, begin to fertilize it every two weeks with a water-soluble houseplant fertilizer at half-strength. They bloom best when pot bound. Repot your Clivia every three to five years in the spring, after the flowers fade, when necessary.
By Debra Ricigliano, Lead Horticulturalist, University of Maryland Extension Home and Garden Information Center. This article was published originally in the December 2019 issue of Washington Gardener magazine. Read more posts by Debra.
Have a plant or insect question? University of Maryland Extension’s experts have answers! Send your questions and photos to Ask an Expert.
Late-winter through mid-spring and early through mid-fall are the best times to plant woody ornamentals, so this is a good time of year to start planning your process if you are interested in adding shrubs or trees to your landscape this year.
Take a look at this video showing you how to plant your container-grown tree, and for more information, view the HGIC page on the planting process.
This is a good time of year for cleaning up tools, getting containers ready for starting plants, and maybe even building a Salad Table! The first University of Maryland salad tables were constructed at the Home & Garden Information Center in 2006. The idea for a waist-high raised container garden was based on a row of metal frames on legs I had seen at the edge of a woods at the Accokeek Foundation’s Ecosystem Farm. It was August and the shallow frames were filled with beautiful salad greens. I adapted the design to make it relatively easy and inexpensive to build.
The “University of Maryland Salad Table” carries a State of Maryland trademark for name recognition but was always intended to be an open-source gardening tool. It was popularized in a New York Times article by Anne Raver (a former UME master Gardener!), and by an appearance on the Martha Stewart Show. It has been built and used by gardeners of all ages and circumstances. Videos and building and growing instructions for Salad Tables and Salad Boxes are on the HGIC website. Continue reading →
Q: This spring I plan to buy treated lumber to build raised vegetable beds. Please give me a heads-up on treatment options for lumber. I know CCA is out. ACQ is supposed to be somewhat safe.
Answer: CCA-treated wood (containing copper, chromium, and arsenic) is no longer available for residential use as of 2004. The relatively new chemical treatment ACQ (alkaline copper quaternary) is safe to use in food gardens. Some of the copper may leach over time from the lumber, but the risk to human health is considered to be low. From research we have seen, a toxic level of copper would kill the plants before the edible fruit, roots, or plants would be harvested. If you have doubts, select a different material such as brick, stone, and untreated or plastic lumber. You can forego any enclosure by mounding soil 4-6 inches above grade, leveling the top and sloping the sides.
By Ellen Nibali, Horticulturist, University of Maryland Extension Home and Garden Information Center. Ellen writes the Garden Q&A for The Baltimore Sun.
Have a plant or insect question? University of Maryland Extension’s experts have answers! Send your questions and photos to Ask an Expert.
Happy New Year! At the beginning of January we typically think through what we plan to do better in the coming twelve months in all aspects of our lives, whether that’s reading more books or committing to a fitness program or eating healthy. Of course we don’t always follow through, but it’s still worth considering what might make our lives better–including our gardening lives! Here’s just a snippet of what I’m focusing on in 2020. Continue reading →
