Category Archives: Master Gardener News Release

Caring for Poinsettas

I could have used this information a few years ago.

I could have used this information a few years ago.


AMES, Iowa – The poinsettia is one of the most popular potted flowers in the United States. These colorful plants can be found in nearly every household or business during the December holiday season. However, taking care of this festive flower can sometimes be tricky.

Iowa State University Extension and Outreach horticulturists give tips on how to care for poinsettias for a perfect holiday display. To have additional questions answered, contact ISU Hortline at 515-294-3108 or at

Why is my poinsettia dropping some of its leaves? 

The leaf drop is likely due to some type of environmental stress. Improper watering is the most common reason for leaf drop on the poinsettia. Over-watering will cause the lower leaves to turn yellow and drop. Plants that are allowed to get too dry will wilt and also drop leaves. 

The water needs of a poinsettia can be determined with your finger. Check the potting soil daily.  When the soil becomes dry to the touch, water the plant until water begins to flow out of the bottom of the pot.

The pots of most poinsettias are set inside decorative pot covers. When watering these plants, carefully remove the poinsettia from the pot covering, water the plant in the sink, then drop the poinsettia back into its pot cover. 

Also, make sure the poinsettia is not located near a heat source or cold draft. Warm, dry air blowing across the plant from a furnace register or rapid temperature fluctuations, such as near a door, can also cause leaf drop. 

My poinsettia suddenly wilted and died. Why? 

The sudden death of the poinsettia was likely due to a root rot. Pythium and Rhizoctonia root rots typically occur when plants are watered too frequently and the potting soil is kept saturated. Allow the surface of the potting soil to dry to the touch before watering poinsettias. Also, don’t allow the poinsettia pots to sit in water. Discard excess water which drains into pot coverings or saucers. 

Small, white insects flutter about my poinsettia when I water the plant. What are they and how do I control them? 

The small, white insects are likely whiteflies. Whiteflies are common insect pests of poinsettia, hibiscus, chrysanthemum and a number of other indoor plants. They are most often noticed when watering or handling a plant. When disturbed, whiteflies flutter about the plant for a short time before returning to the plant. 

Whitefly adults are small, white, moth-like insects. Female adults lay eggs on the undersides of the plant’s foliage. After five to seven days, the eggs hatch into small, pale green, immature insects called nymphs. The nymphs crawl a short distance before settling down to feed for two to three weeks.  After feeding for two to three weeks, the nymphs progress to a nonfeeding stage and then finally to the adult stage. 

The nymph and adult stages of whiteflies feed by inserting their short, needle-like beaks into foliage and sucking out plant sap. Heavy whitefly infestations may cause stunting or yellowing of leaves, leaf drop, and a decline in plant health. 

Whiteflies on poinsettias and other indoor plants are extremely difficult to control. Prevention is the best management strategy. When purchasing plants, carefully check for whiteflies and other insects. Avoid purchasing insect-infested plants.  Insecticides are not a good control option as they are not very effective. It’s often best to tolerate the presence of a small infestation of whiteflies on a poinsettia and then promptly discard the plant after the holidays.


Magnolia Medicine

magnolia-grandiflora-flowerThe leaves of the Magnolia grandiflora and Magnolia virginiana ( southern varieties of magnolias with evergreen leaves) have long  been used by indigenous populations in the Southeast for medicine.

Modern research has confirmed this practice.   M. grandiflora contains phenolic constituents shown to possess significant antimicrobial activity, several of which exhibit significant action against Gram-positive and acid-fast bacteria and fungi. The leaves of  M.grandiflora contain coumarins and the sesquiterpene lactones: costunolide, parthenolide, costunolide diepoxide, santamarine and reynosin. M. virginiana has been shown to have two additional sesquiterpenes: ostunolact-12β-ol and its acetal dimer.

I have heard many herbalists say that medicinally speaking all magnolias species and dogwood are interchangeable, but I question if that extends to the varieties that grow locally.

I’ve never been lucky enough to be in Nashville to see my husband’s grandmother’s trees bloom, but I have had a chance to munch on some spring leaves. Given that it is the the sesquiterpene lactones in the leaves which account for the plants actions, I really don’t believe after having smelled and tasted the grandiflora leaves that our local variety have nearly the same chemical make-up.

04b8f9f9bb2fd86f4b3c1b8658a8b31cOur trees are pretty but the leaves are very different, they are  deciduous and not nearly so aromatic. The taste, what little there is, seems entirely different. Steve tells me if I ever get to smell a blossom from Grandma’s tree, I will be sure of it.
Whether this is due to variety or growing in a different climate, the plants of the magnolia species that are hardy enough to make in Iowa are such a different creature that I don’t understand how they could possibly have the same energetics and actions and I haven’t been able to find much on their sesquiterpene content.  My guess is that the northern deciduous varieties are not nearly so potent,  although there has been some interesting work done in identifying  the acetylcholinesterase inhibiting chemical taspine in the Magnolia x soulangiana species, which will grow here in Iowa.

This seems to be supported by  its  traditional  by various indigenous groups.   It has been mentioned that various groups utilized the bark of Magnolia acuminata L for stomach ailments and toothaches.   The active constituents in M acuminata bark may be the lignans present in the bark and root. While that variety is hardy in this area, it is not necessarily native to Iowa.

That being said I do have a nice press release from the ISU archives on which magnolias grow well here.

Magnolias for Iowa Gardens

By Cindy Haynes
Extension horticulturist
Iowa State University Extension

One of the most beautiful groups of flowering trees is the magnolia. The regal flowers of southern magnolia (Magnolia grandiflora) grace landscapes throughout the southeastern United States. They have even appeared on a postage stamp. However, this southern beauty is just that… southern. Southern magnolia will not tolerate Iowa’s harsh winters. However, there are several other magnolia species with equally attractive flowers that perform well in Iowa. Their elegant flowers appear from early April through May.

Magnolias are a diverse group of plants with pink, purple, white and even yellow flowering types. Flowers on most are fragrant, varying slightly with species. Plant size can vary greatly as well. Many are medium to large trees with some reaching more than 50 feet tall. Others are considered large shrubs only reaching 8 to 12 feet tall. Because of their diversity, there is a magnolia for virtually every site in the landscape.

Cucumbertree magnolia (Magnolia acuminata) is native to the United States from Louisiana to New York. It is hardy to Minnesota. This tree is “large” in many respects. The leaves can be up to ten inches long and the tree often reaches 50 feet or more in height. However, the flowers are relatively small — only 2 to 3 inches long and greenish yellow in color. While the flowers are quite attractive, they are not readily seen since they are often hidden by the foliage. Flowering begins in late spring and is rarely affected by frosts. The fruit, appearing in late summer, is worth searching for since it resembles a cucumber, hence the common name.

While the flowers on the cucumbertree magnolia often go unnoticed, the blooms of some of its offspring are quite showy. Because of their unusual greenish yellow flowers, the cucumbertree magnolia has been crossed with other magnolia species to develop yellow-flowering selections. ‘Elizabeth’ was the first yellow-flowering magnolia sold and is still one of the best available on the market today. Recently, several other yellow magnolias have been introduced. Competitors such as ‘Butterflies,’ ‘Yellow Bird,’ ‘Yellow Fever,’ ‘Yellow Garland,’ ‘Sundance’ and ‘Miss Honeybee’ reportedly offer more vibrant yellow flowers. Only time will tell if they can surpass the elegance of ‘Elizabeth.’ ‘Elizabeth’ will reach 30 feet tall with a 15 to 20 foot spread. Unlike the cucumbertree, the yellow magnolia hybrids flower before the leaves emerge fully in spring, making the show much more spectacular. Since the yellow-flowering hybrids bloom later than most magnolias, they are rarely damaged by frosts.

Another large magnolia with showy flowers is the saucer magnolia (Magnolia x soulangiana). Sometimes called the tulip tree, this magnolia puts on a spectacular show producing large, pinkish purple flowers in early spring. When this tree is in full bloom it can stop traffic. The flowers are lightly fragrant. Unfortunately, our fickle weather in early spring can be a problem. Freezing temperature can turn beautiful flowers into dead, brown masses. Give this species plenty of room, since saucer magnolia normally reaches 30 feet tall with a spread of 20 feet.

In locations where smaller trees are needed, the loebner magnolias (Magnolia x loebneri) are excellent choices. With heights from 15 to 25 feet, they are suitable for sites near the home. ‘Merrill’ is one of the hardiest of the loebner magnolias surviving beautifully at the Minnesota Landscape Arboretum (USDA Hardiness Zone 4a). The white flowers are smaller than the saucer magnolia but contain more petals (tepals, technically). They also flower a couple of weeks later than the star and saucer magnolias, oftentimes escaping injury from late frosts. ‘Leonard Messel,’ another lobener magnolia cultivar, is noted for its pale pink flowers.

Coming down in size once again is the star magnolia (Magnolia stellata). Star magnolia is the first magnolia to bloom. As a result, the flowers are occasionally zapped by late spring frosts. Don’t cross the star magnolia off your list because its white flowers are occasionally destroyed. In 3 or 4 years out of 5, it’s fantastic! Flowers are smaller than those of saucer magnolia but the petal count is much greater. Mature heights range from 12 to 20 feet with spreads around 12 feet. It is also one of the hardiest magnolias.

For plants with smaller statures but equally impressive floral displays there is the Little Girl series of magnolias. This series of hybrids was developed at the National Arboretum in the 1950s for shrub-like form and colorful flowers. Each of eight different cultivars, aptly named ‘Jane,’ ‘Judy,’ ‘Betty,’ ‘Ann,’ ‘Ricki,’ ‘Susan,’ ‘Randy’ and ‘Pinkie,’ are large shrubs ranging in height from 8 to 15 feet. Flowers vary slightly between cultivars but are generally challis-shaped and usually pink or purple in color. Flowers appear later in the spring season thus avoiding destruction by late spring frosts. Flowers usually appear just prior to or with the emerging leaves. The habit varies slightly between cultivars with ‘Ricki’ being rather upright and ‘Betty’ more spreading or rounded.

Planting and Maintenance

Magnolias prefer a full sun location with well-drained soils. They are adaptable to soil types, even tolerating clay soils, but they insist on good drainage. Waterlogged soils often lead to an early demise. Spring planting of larger specimens is best as most root growth occurs in spring.

Magnolias are relatively pest and disease free. On occasion, magnolia scale or mildew will attack a tree. These problems only warrant treatment in severe cases as they tend to be cyclic in nature. Contact your county extension office for treatment options if problems arise. As one magnolia aficionado once said, “Their biggest problem is not pests, it is that they don’t flower long enough.”

Magnolias are considered one of the oldest families of flowering plants. They have survived on earth for thousands of years. Thankfully they are still around to add a little elegance to our landscape every spring.

Alice Clark et al., “Antimicrobial activity of phenolic constituents of magnolia grandiflora
L,” Journal of Pharmaceutical Sciences 70 (1981) 951–952.

Blunden Yang et al., “Coumarins and sesquiterpene lactones from Magnolia grandiflora leaves,” Planta medica,60 (1994): 390-390.

J. Rollinger et al., “Taspine:  Bioactivity-Guided Isolation and Molecular Ligand−Target Insight of a Potent Acetylcholinesterase Inhibitor from Magnolia x soulangiana,” Journal of Natural Products 69 (2006): 1341-1346.   

S. Farouk et al., “Isolation and characterization of the sesquiterpene lactones costunolide, parthenolide, costunolide diepoxide, santamarine, and reynosin from Magnolia grandiflora L.” Journal of Pharmaceutical Sciences 67 (1978) 347–350.

Q.Song et al., “Sequiterpenes from southern Magnolia virginiana,” Phytochemistry 47 (1998): 221-226.

Buying and Caring for a Real Christmas Tree

For Immediate Release  from Iowa State Extension


AMES, Iowa — Buying local often times means buying locally grown food, but in December, it also can mean buying a Christmas tree from a local grower. Christmas trees are grown in Iowa and all 50 states. There are approximately 100 choose and harvest farms in Iowa, where the top selling Christmas trees are Scotch pine and white pine. Iowa State University Extension and Outreach horticulturists provide tips on fresh Christmas trees. To have additional questions answered, contact Hortline at 515-294-3108 or

Carrying the tree on your own- a rite of passage.

Carrying the tree on your own- a rite of passage.

What factors should be considered when purchasing a Christmas tree for the holidays?

A few decisions should be made before going out to buy a Christmas tree. Decide where you are going to place the tree in the home. Be sure to choose a location away from heat sources, such as a fireplace or radiator. Also, decide on the size (height and width) of the tree you want.
Christmas trees may be purchased from cut-your-own tree farms or as cut trees in commercial lots. A list of tree farms in your area can be found at the Iowa Christmas Tree Growers Association website at Carefully check trees at commercial tree lots to ensure the freshness of previously cut trees.

Tree species commonly available at tree farms and commercial lots in Iowa include Scotch pine, white pine, red pine, Fraser fir, balsam fir, Canaan fir, Douglas fir, white spruce and Colorado spruce.

When looking for a tree, select one that has a straight trunk. A tree with a straight trunk will be much easier to set upright in the stand. Check the diameter of the trunk to make sure it will fit in your stand. A tree with a bare side may be fine if you intend to place it in a corner or against a wall.195353666859
How can I determine the freshness of a cut Christmas tree?
The freshness of cut Christmas trees can be determined with a few simple tests. Gently run your hand over a branch. The needles on a fresh tree will be pliable. Those on a dry tree will be brittle. Another test is to lift the tree by the trunk and lightly bounce the butt on the ground. Heavy needle drop indicates a dry tree. A fresh tree will drop only a few needles.
What is the best way to store a cut Christmas tree?
If you don’t intend to set up the Christmas tree immediately, place the tree in a cool, sheltered location. An unheated garage or shed is often a suitable storage site. (The sun and wind dries out trees stored outdoors.) Put the butt of the tree in a bucket of water. Cut off the bottom 1 inch of the tree’s trunk before bringing the tree in the house. A fresh cut facilitates water uptake.
Should I add any material to the water to prolong the freshness of my Christmas tree?
Do not add molasses, sugar, soft drinks, aspirin or commercial products to the water. Additives provide no real benefit. The keys to keeping a Christmas tree fresh are to place the tree away from any heat source (fireplace, heater, radiator, etc.) and keep the tree reservoir full of water. Check the tree reservoir at least once or twice a day. Fresh trees absorb large quantities of water (especially in the first few days). If the water level drops below the bottom of the trunk, water uptake will be drastically reduced or cease when the reservoir is refilled.
How long can a cut Christmas tree remain in the house?
The length of time a cut Christmas tree can remain in the home is determined by the tree species, the freshness of the tree at purchase, and its placement and care in the home. In general, a fresh, well-cared-for Christmas tree should be able to remain in the home for three to four weeks. Remove the tree from the house when its needles become dry and brittle.
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