Gardenias and Spider Mites, Yikes!

 Photo by Rebecca (Used with Permission)

Photo by Rebecca (Used with Permission)

This week I got an email from Rebecca.  She was trying to help her mother take care of a plant she got as a mother’s day gift from her brother.  Her particular problem would’ve been a brain teaser for me had it not been for her excellent description and the photo she included.  Remember, anytime you need gardening advice feel free to contact us at ask@bobsmarket.com.

From Rebecca:

I am trying to help my mother with a plant she received from my brother.  It has been losing its leaves.  I am not sure if you can see in the attached photo, but there are little webs and light tannish colored gnats or something similar, crawling in the web.   My brother wasn't sure of the plant name so I did not want to spray it until I knew what to use.  The leaves resemble a bay leaf and the plant had small white flowers when he gave it to her.
Would you please advise what the plant name is and/or how to treat its condition?

I’ve seen this firsthand in my own home.  The plant is a gardenia.  It is grown for its white, fragrant flowers and the pests are spider mites.  To fight them we first need to identify the cause of the infestation, and then take a look at some techniques to get rid of the little buggers.

Many people wonder why they receive a gardenia plant full of blooms and buds and within weeks, the plant drops its flowers, loses it buds, and starts to die. The answer lies in the conditions in which you're growing the gardenia.

Light

Gardenias need bright, indirect light. Inside the home, this means near a sunny window but not necessarily sitting on the windowsill itself. A southern-facing room is ideal, with the plant placed somewhere inside the room but not sitting under the burning rays of the sun all day. Most indoor plant lights provide the right amount of light but you may need to experiment with how close the gardenia remains to the light source, moving it closer or further away as need be.

During the spring, summer and early fall, a southern window may provide all the light your gardenia needs. In the winter months, many gardenia lovers supplement the natural light in their homes with artificial plant lights to keep their gardenias happy. The lower angle of the sun and shorter days makes even southern-facing natural light limited for the gardenia, and adding another light source helps provide the bright conditions the plant needs to remain healthy.

Humidity

The hardest part of gardenia indoor care is keeping the humidity high enough, especially in the wintertime. Those who live in homes with hot air heating know the awful drying effects such a heating system has on the skin and hair of people. On plants, it's even worse. You can buy a hygrometer or a combination thermometer and hygrometer and keep it by your indoor plants to measure the relative humidity and adjust it accordingly. Hygrometers measure humidity, while thermometers measure temperature. Gardenias prefer the relative humidity around 50 to 60 percent. To increase the humidity near your plants, you have several options. First, you can purchase an inexpensive spray bottle and mist plants daily. If that seems like too much work, you can also place the plant on a dish or saucer filled with gravel or pebbles. Add water daily to the pebble tray. As the water evaporates, it will increase the humidity near the plant. A humidifier for your home can increase humidity to comfortable levels throughout the house or room by room, depending on your needs.

Water

While gardenias don't like to be saturated with water, a constant supply of moisture ensures the plant retains it blossoms and remains healthy. To tell if your gardenia needs water, stick your finger into the soil. If it feels dry, water it. If the soil is so soggy it feels squishy, you're watering it too much.

 

 

Soil

Speaking of soil, your gardenia will need rich, well-drained soil. Try an organic potting soil for the healthiest plants. The soil needs to be a bit acidic for best results. Get a soil tester kit and check it. The best soil for gardenias should have a pH between 5 and 6.If the soil is lacking in acidity, there are a few things you can do. Some gardeners swear by adding pickle juice to their gardenia soil. Vinegar may work just as well, just be sure it is diluted in water because vinegar can kill plants and is often used as a natural herbicide to get rid of weeds. Dilute at a ratio of one cup vinegar or pickle juice to one gallon of water and use it to water your gardenias once a month. You can also use a product called Miracid to keep the soil at the right acidity for your acid-loving houseplants.

One thing to keep in mind if you have just purchased your gardenia is that is probably in the correct soil already. It isn't a good idea to repot a new gardenia because it will probably go into shock and drop all its buds. Gardenias do best if they are slightly root-bound so there is really no need to repot it unless you see roots coming out of the top of the plant. If you don't like the pot it is in, just place it inside a slightly larger, decorative pot.

Fertilizer

Indoor gardenias need the same or similar fertilizer as their outdoor cousins. Use a fertilizer specially formulated for gardenias. Any fertilizer used for plants that like acidic soil also works well. Use fertilizer according to the label directions.

Pruning

Deadhead or remove spent blossoms. Don't be afraid to prune your gardenia as necessary. Pruning encourages healthy new growth and blossoms. For most gardenia varieties, pruning should be done right after the plant is done blooming. If you wait too long to prune, it will not bloom the next year.

Don't Give Up On Gardenias

Don't give up on gardenias if your first plants fail to thrive or die. Gardenias can be tricky. For some people, growing the perfect gardenia becomes an all-consuming passion. The quest for the perfect scented creamy-white blossom makes growing gardenias a rewarding hobby for the amateur horticulturist.

OK Onto Spider Mites

If your gardenia isn’t provided the best environment, it can weaken the plant and make it an easy target for spider mites. These small creatures suck nutrients and juices from the leaves of plants, causing discoloration and yellow blotches. They can form a spider-like silk web on the underside of leaves for purposes of protection and, if left unchecked, a web over the entire plant, severely stunting growth or killing it. Spider mites can float along with summer wind currents or be carried by garden visitors such as raccoons, pets, or infected plant material. To spot these mites, first look at the plant leaves and if they appear to have a rash of tiny yellow pinpricks all over the surface, any discoloration coupled with unexpected leaf drop, suspect this pest as the cause. The tiny mites will be visible to anyone with good eyesight, but using a magnifying glass also helps. These are some nasty bugs whose populations can increase dramatically if not thwarted! These insects are the true survivors of the insect world.

 Photo by:  Gilles San Martin

The adults are very small, about 1/60 of an inch long, are oval in shape, and range in color from green to brownish orange, light yellow or sometimes simply clear. Depending upon the ambient temperature, adult spider mites, who are not flyers and have no wings, live from one to four weeks. A complete life cycle requires two to three weeks, but if the weather is very hot, it can be as short as one week. Mites can over-winter as mated females in protected areas and garden debris, so good garden hygiene in fall is helpful in reducing their numbers. Adult females have the ability to go dormant when daylight hours shorten, then re-emerge to lay more eggs a few weeks later, which is why the pest keeps reappearing crop after crop, especially on indoor house plants.

In good conditions, spider mite eggs can develop into adults in just one week. Inspecting leaves for mites you will commonly see both eggs and adults all together. Spider mite eggs are all perfectly round, the same size, ranging from amber to clear in color. Females can lay 100 or more eggs in their short lifetime!

You can use an insecticidal soap, malathion, neem oil or a miticide product containing dicofol (Kelthane) to kill mites. You must apply these using a higher pressure spray so as to force the spray into the mites themselves, and you must re-spray about two days later, to kill the new mites that hatched from eggs, which are not affected by the spray. Mites are survivors and don’t kill easily.

When hosing off a plant, make sure to spray the entire plant, bottom to top, as well as the undersides of the leaves using a hard spray of water, remembering that they can’t crawl back once knocked off.

Natural enemies include lady beetles, predatory mites, minute pirate bugs, big-eyed bugs and predatory thrips. Using carbaryl (Sevin) kills some mites, but mostly mite predators, which can cause an explosion of mite populations later on.