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Bromeliad, Greenhouse

Solutions to Common Winter Houseplant Issues

The natural beauty of houseplants can really boost our moods and take the bitterness out of a cold winter. Creating an oasis with flowering or bright foliage plants can really chase away the winter blues. But the dry, heated indoor air and limited natural light at this time of year can create a difficult environment for our foliaged and flowering friends. With a little extra knowledge, you can keep your plants healthy throughout the season and resolve many of the issues that houseplants commonly experience.

Too Much or Too Little Water

Seasonal changes in plant activity and the environment in which they are placed can impact the amount of water that your plant needs during the winter months. If your plant is yellowing or wilting, it is trying to tell you that it is under stress. Most often, the main cause of stress in houseplants has to do with watering too much or watering too little. 

Plant roots need oxygen to live and grow. If the soil remains saturated for an extended time, the roots will drown and lead to the loss of the plant. Make sure that the container you’re using has drainage holes and that nothing is obstructing the holes. This will allow excess water to drain out of the container.

The best way to check whether your plant is too wet or too dry is to feel the soil. On smaller plants, you can use a pencil, chopstick or your fingers. On larger plants, you can use a moisture meter. Plants have different preferences when it comes to their soil moisture, but most often, you will want to wait until the soil feels slightly dry before watering again. When you do water, water thoroughly until the it’s draining from the hole of your pot. 

In general:

  • Winter-flowering plants typically need more water. Some plants, like zygocactus and Christmas cactus, need more water during the winter when they go through their flowering stage.
  • Plants that are not blooming during the winter use less water. However, you will need to check the soil as the environmental conditions in your home will have a large impact on the amount of water your plants need.

Leggy Plants

Leggy plants are easy to recognize as they have a stretched out and spindly look. Often, the stems and shoots will flop over since this type of growth is not structurally sustainable. Fortunately, you can easily make some adjustments to prevent leggy plant growth. 

Too little light: A plant that is happy in a sunny spot during the summer may struggle to get enough light in the same spot during the winter months depending on the changing angle and duration of light. Give your plant more light by moving it to a brighter location or supplementing the natural light with a light bulb designed for plants.

Too much nitrogen: Plants that are fertilized too often will develop leggy growth as a reaction to the overabundance of nitrogen. Many plants are less active in the winter months and need to be fertilized less. If you see leggy growth out of a plant that is regularly fed,try dialing back the frequency and amount of fertilizer the plant receives. 

Repotting in a Container That’s Too Large

Oftentimes when plants are struggling our first instinct is to repot the plant to give it more space. However, in the winter this may not be the best solution. Many houseplants actually like to have roots that are a little snug in their pots and only need to be sized up every couple years. The best time to repot is in the early spring when sunlight is increasing, but even then you should only increase the size of the planter by 10 to 20% at a time or you risk harming the plant.

Pests

Pests can be an issue particularly for houseplants that spend time outdoors during the summer months. The pests that are controlled by natural predators and the environment outdoors can get out of control when brought inside for the winter. To prevent pests before they start, spray plants that go outdoors for the summer before they come back inside with a neem oil or insecticidal soap. You can gather all of your plants that are coming inside in a group, then spray them with a hose end horticultural oil. Focus on the interior of the plant and the undersides of the leaves, then allow them to dry for an hour before bringing them inside.

Keep an eye on your plants during the winter and know how to identify honeydew and other early signs of pests to help eliminate potential problems before they get out of hand.

Mealybug and Scale

To the untrained eye these insects may appear to be fungus, lumps, disease, or some unknown substance. Mealybugs and scales are small, sometimes microscopic, insects that make a home for themselves out of waxy or cottony structures for protection while they feed on your plant. 

Catch mealybugs and scale early by checking your plants regularly for “honeydew,” a sticky liquid that may appear before the insects are visible. This is a sure sign of an early infestation, and means you should begin spraying your plants with mineral oils or insecticides whenever there is an opportunity to do so. Spray plants outdoors on days when the weather is around 50 degrees or warmer, or in a ventilated area inside that is free of belongings that could be ruined by oil based sprays. If you do not have a convenient area to spray your plant, try a systemic insecticide, which can be applied directly to the soil or used to sanitize pots that held infected plants.

Spider Mites

Spider mites are almost entirely invisible to the naked eye, so their presence is usually identified by microscope. However, you can detect the presence of these pests by looking for leaf stippling, which makes the leaf look spotted and is caused by the repeated puncturing of the leaf when these pests feed on the plant. Spider mites will also make web-like structures underneath the leaf and inside the plant for protection against predators. 

Insecticide soaps can be a gentle and useful way to control these unwanted critters. Horticultural oils are also very useful to eradicate both active adults and eggs, but need to be sprayed outdoors or in areas where they can’t stain valuable furniture or belongings. You will need to spray multiple times to eliminate both the eggs and the mites.

Gnats and Whiteflies

Whiteflies on foliage.

Some plant pests primarily create a nuisance in the home. Fungus gnat larvae, for example, thrive in damp soil mediums while the adults fly around our homes and annoy us to no end. To prevent fungus gnats, select high quality potting soils labeled for indoor use and place plants in containers with good drainage. If the problem is already out of control, try using sticky traps to eliminate adults while treating the soil with an insect control like Bt or Eight to deal with the larvae.

Whitefly adults and larvae pose a more serious issue as they feed on our plants. Sticky traps are also a great way to control whitefly adults and spray insecticides can be used to control the larval population, as with the fungal gnats. Insecticidal soaps and mineral oils are great control options for this purpose.

Visit Our Plant Clinic for Additional Assistance

If you have questions about your plants, we encourage you to bring them into the plant clinic. During the winter, bring them in on a mild day, or be sure to wrap them up and protect them from the cold weather in transit. You can also bring plant samples if you are unable to bring in the whole plant. If you’re bringing in photos, please bring an image of the entire plant and a close up of the areas of concern.

Managing Grubs in Your Lawn and Garden

Have you been noticing large patches of dead grass in your lawn that peels up like a carpet? If so, you may have a problem with grubs. Don’t fret! These pesky critters are one of the most common pests in our gardens and luckily, they can be managed. However, before you can get rid of these menaces, you must understand them! Check out our information below and if you find yourself with any lingering questions, call one of our three locations or come by the Plant Clinic to speak with a plant specialist.

What are Grubs?

Grubs are the larval stage of any beetle or scarab. There are many varieties of scarabs in our area that can cause serious damage to turf grass. Beetles like masked chafer, green June beetle, and may beetle are native beetles that can sometimes cause damage to the lawn. More serious pests like the invasive Japanese and Asiatic beetles will frequently cause damage in the lawn.

Japanese Beetles  (Popillia japonica)

Japanese Beetle

Japanese beetles were unintentionally introduced to the United States in 1916 and today they can be identified in over half of all U.S. states. Adult beetles have a copper elytra (wing covering) with metallic-green coloration and actively feed throughout the summer. Adults are active during the daytime and may be found on a large variety of ornamental and agricultural plants, in particular on roses or pear, apple, plum and cherry trees.

Asiatic Beetles  (Maladera castanea)

https://grubid.cals.cornell.edu/node/1

Asiatic beetles were also first detected in New Jersey in 1922. The adult beetle is 3/8” long and cinnamon-brown. The adult actively feeds and lays eggs during the night time. Shine a flashlight on the ground to identify active beetles in your garden beds. Asiatic beetles also feed on a wide range of plant material.

Grub Damage and the Grub Life Cycle

https://cues.cfans.umn.edu/old/extpubs/7664japanese/7664f08.jpg

Understanding the life cycle of these beetles can mean the difference between success and failure in working to effectively control them. Both Asiatic and Japanese Beetles have a single generation each year, with adults feeding through the summer and grubs overwintering in the soil, then becoming active as the soil warms up and they begin to eat root material. In late May or early June adults emerge from the ground to breed and continue feeding.  Females will typically burrow into the soil of the lawn to lay eggs in mid-July. Grub stage sod damage may become evident during August and September when grubs are aggressively feeding in order to store energy for the winter. 

Adults Japanese and Asiatic beetles eat the tissue between leaf veins on ornamental and agricultural plants, giving the appearance that the leaves have been ‘skeletonized.’ They also frequently go after ripening fruit and will even eat the flowers of roses and other members of the Rosaceae family. However, what makes these invasive beetles such a serious pest is that not only do the adults cause extensive damage to plants; the larvae are also voracious eaters, particularly of sod roots. In cases of heavy grub infestation it is very common that this will result in large dead patches of grass that quickly turn yellow or brown.

Via Michigan State University - https://www.canr.msu.edu/news/how_to_choose_and_when_to_apply_grub_control_products_for_your_lawn

Upon inspection, this damaged turf will peel right up from the ground with very little effort.Often you will also see many of the culprits still lurking below the surface as you investigate. This makes grubs very easy to identify; however, it is best to identify grubs as they are just becoming active, before they become a detriment to our landscapes. This is usually sometime in early to mid-May and middle to late August. To identify a grub infestation, cut three sides of a square-foot section of grass and carefully lift the sod up to avoid damaging the sod. If you see more than five or six grubs in that small space, it is time to get moving on grub control. 

Conventional and Organic Control Options

Conventional

Season Long Control: With proper timing, season long control products such as BioAdvance Season Long Grub Control are the most effective methods to treat and prevent a grub infestation The ideal time to apply is before adult beetles emerge. For the Northern Virginia area, we recommend application of these products during the last week of May. If you are not sure whether adult beetles have emerged or not, you should call the garden center to speak with a plant clinic representative.

24-Hour Grub Killers: Should you miss the window for effective application of season long products,24-hour grub killers can be effective at wiping out a population of feeding grubs overnight. These products usually contain strong pesticides such as Dylox, which kill many other lawn pests such as ticks. 

When applying these products, remember to always read the label instructions and follow them exactly to ensure safe application. Also, while products like those listed above can help us to control unwanted garden pests, they can also have an impact on ‘beneficial’ insects as well. Many chemicals listed for control of grubs have shown to impact fireflies, solitary bees, ladybugs and other desirable garden insects. For this reason application of these chemicals is only recommended to control serious infestations.

Organic

Organic alternatives to conventional pesticides have been used to control Japanese beetle grubs for decades.  These alternatives are more selective in their control and less likely to impact beneficial insects.

Milky Spore: Paenibacillus popilliae is a spore-forming bacterium which is pathogenic to grubs. The commercially available milky spore is exclusively pathogenic to Japanese beetle larvae. In order to be effective the spores must be ingested by the grubs. Once the grub is infected, it has a white appearance which contributed to the name of this product. For milky spore to be effective, there must be a significant grub population where it is applied to the soil. 

Milky spore can be hand applied in its powder form in one application, or there is a granular form that can be spread using a lawn spreader more easily, but requiring more applications over a longer time frame.

Beneficial Nematodes: Beneficial Nematodes can be used to control various garden insects such as moths, ants, and most importantly grubs. As with milky spore, the denser the grub population is the more effective the nematodes are at spreading and infecting the grubs.The best time to apply them is during August, when young grubs are feeding on root material. Nematodes will work quickly to control grubs but they can be very sensitive to environmental conditions. Bright sunlight in particular can kill nematodes, so it is recommended to apply them at dusk or during a rainy day for best results.

Controlling Adult Populations

Other methods of effectively controlling beetle grubs involve going after the adults. There are many insecticides that can be used to control adult populations on garden plants. Furthermore, many extension services and universities recommend using pheromone-baited beetle traps to control adult beetles as well as removing and destroying adult Japanese and Asiatic beetles when discovered in the landscape. If you have questions about these options or any others, please give us a call or visit the plant clinic at one of our stores.