Caring for Plants in the Home Q. 1-20

1. Q. My "Bird-of-Paradise" finally bloomed and it was beautiful! During the blooming process I cut each bloom (bird) as they wilted. Once it stops putting out birds should the flowering stem be cut or only the pod?

A. After a "Bird-of-Paradise" bloom fades, it is a good idea to cut the bloom stalk at the base to keep the plant looking tidy. It does not hurt to remove the fading bloom at the top of the bloom stalk and then remove the stalk later when it fades. Whether you follow this procedure or remove the entire stalk once the bloom fades does not influence the continued growth or next year's bloom potential of the Bird-of-Paradise plant. It is more important to grow the plant in a suitable size, large container. Good growing conditions will encourage the numerous healthy leaves necessary for good bloom. Bird-of-paradise plants require bright light with at least 4 hours a day of direct sunlight to produce blooms. Normal room temperatures will suffice during active growth periods, but they need a long, cool rest at around 55 deg F day and night during the fall and winter. During active growth water the plant thoroughly, but allow the top inch of soil to dry out between watering. During the resting period, water just enough to keep the soil from drying out entirely. Feed with a liquid fertilizer every two weeks during active growth only. Repot young plants to larger pots as needed each spring, but once a plant begins flowering refrain from repotting it as this may keep it from flowering for a year or two. Instead, topdress the plant with fresh potting mixture each spring.

2. Q. Please tell me what disease looks like small bits of cotton on my African violets and what to do for it.

A. The appearance of what looks like small bits of cotton on African violets is mealy-bugs, a sucking insect pest, not a disease. Mealy-bugs are soft insects that have whitish, cottony or mealy substance around them. They often leave bits of this material on plant or leaf stems when they move around. Mealy-bugs on an African violet can be controlled fairly easily by one of three methods:

  • Use one of the ready made houseplant insect controls that mentions mealy-bug control for African violets. Use the spray, which may be aerosol or finger pump, as recommended. Read all label directions and precautions. Repeat applications are usually suggested.
  • Use a cotton tipped swab dipped in rubbing alcohol to gently dab away the pests. This may be tedious, but it is effective. Repeat treatments like this are usually necessary since this method may not eliminate all of the mealy-bugs.
  • Use a mixture of one cup rubbing alcohol, teaspoon Volck oil, and one quart of water in a plant mister to gently mist the African violet portions where the mealy-bugs are present. The alcohol will dry out the bugs. This should be done when the violets are not in bright light. Alcohol mistings may have to be repeated every 7 to 10 days for complete control. Do not use straight alcohol as that may result in damage to the plant.

Actually, a combination of the second and third methods should work well together to eliminate the mealy-bug infestation on an African violet. Mealy-bugs are one of the insect pests on indoor plants that may reappear in several weeks after an infestation has been eliminated. Thus, it will be important to watch the affected plants carefully in the coming weeks for future problems.

3. Q. I have a fairly large weeping fig plant in my house that has developed a clear, shiny coating on many of the leaves. The plant still looks good. Is this something to worry about?

A. The shiny coating on the weeping fig leaves may be a residue left behind from aphids feeding (sucking) on the newer growth; scale insects can also leave clear secretions. Sap that has been secreted from the leaves may also be the cause of the coating. Look closely at the plant to seek clues.

The aphids that can get on an indoor plant are often a light green color. Since they love to get around the most tender parts of a plant, they may be noticed around the ends of the branches. Also, look on the underside of leaves. Scale insects look like tiny disks and can be either on the leaves or the stems. The actual insect is under the disk.

If you detect aphids on your plant, wash them off using soapy water. Do not use detergent as this may damage plant tissue, and be sure to rinse the plant well. Scale insects are more difficult to eliminate as they can only be killed while in their crawler stage, when they are not protected by their hard scale. Prune off and dispose of any affected leaves and branches. If this in not possible, use one of the ready-made house plant insecticides sold at some garden centers or hardware stores. These materials made for house plants should be safe for indoor use, but be sure to follow all label directions. Repeat either treatment in about 7 days for complete control. Since you mentioned that your fig still looks good, you may not have anything to worry about. However, keep a continued watch for changes in the plant.

4. Q. What are `Persian violets'? Are they related to African violets?

A. Persian violets are not related to African violets, but they do make as nice a houseplant. There are actually two plants commonly known as Persian violets, Cyclamen purpurascens, the florist's cyclamen, and Exacum affine, also known as German or Arabian violets. The florist's cyclamen is usually purchased in bloom. The numerous flowers, varying in color from white to deep red and purple, are held well above the attractive silver marked foliage. The plants will bloom for 2 to 3 months, longer in cooler rooms or when the surrounding humidity is high. Place them in bright light without direct sun and water only after the soil has become moderately dry. Remove faded flowers and leaves. To bring the plant into flower the following year, gradually reduce watering when the blooming period is over. Let the soil dry after all of the leaves fade, and store in a cool place for the summer. As new growth begins in the fall, repot the tuber, bring it into the light, and start watering, keeping the soil barely moist. After the leaves develop, begin feeding every other week with a standard houseplant fertilizer.

Exacum is also generally purchased in bloom. Its lavender flowers with bright yellow centers nearly cover its glossy leaves, making it a very desirable houseplant. Grow it in bright light but not strong direct sunlight, in a room with normally warm temperatures. Place the pots on trays of moist pebbles to provide the high humidity exacum needs. Pinch off fading flowers to encourage more blooms and bushy growth. When the plant becomes straggly, root cuttings to replace the parent plant.

5. Q. How can I tell if my houseplants are getting the right amount of light?

A. One of the most common signs of inadequate light is yellow and dropping leaves. That is also one of the most common signs of too much light. To figure out if either of these situations is your problem, you will have to look more carefully at your plants. Flowering plants that don't flower, any plants with leaves angled toward the light and long, spindly stems, plants such as coleus whose red pigments have faded, or plants whose new leaves are smaller are all showing signs of inadequate light. Either move these plants to a brighter spot or supplement natural light with artificial light. Foliage plants require nothing more than an inexpensive, cool, white flourescent lamp; combine a cool white lamp with a warm red lamp to ensure the best bloom in flowering plants. When your plant's leaves show signs of overall yellowing or have large spots of dry, dead tissue known as leaf scorch or leaf burn, the problem may be too much light. Use a diffuser curtain to reduce the amount of direct sunlight hitting the plant, or move it further away from the window. Even if the light level is correct for a given plant the same symptoms may develop if it was moved straight from a low light intensity to a much brighter spot. Make such moves gradually to allow the plant to adjust to the new light levels.

6 Q. It gets very dry in my house in the winter. Does this hurt my plants? What can I do to help?

A. Most plants prefer a relative humidity of 50-60%. During the winter, most homes have a relative humidity of 10-15%. Low humidities such as these can cause plant leaf edges and tips to brown, flower buds to brown and fall off, and keep the whole plant from thriving. The best solution is to use a humidifier of some sort to raise the relative humidity of the whole house or the room where the plants are located. This will not only help the plants but will make the house more comfortable for human inhabitants. If this is not practical, try growing the plants in the kitchen or bathroom, where the air is naturally humid. Small plants can be grown in a terrarium, where humidity levels are easily kept high. Place plants in groups where the water vapor given off by each plant benefits the others. Even better, group the plants on a tray of moistened pebbles or long-fibered sphagnum moss. This will raise the local humidity to an acceptable level. Misting the plants once or twice a day helps, but is really a very short-term remedy.

7. Q. When should I repot my indoor foliage plants? How do I go about it?

A. Permanent houseplants usually need to be repotted annually until they attain their final size. The best time for this procedure is during a slow growth period, which will be during early spring for most plants. Check the drainage holes of the pots to see if any roots are showing. If so, the plant is probably potbound and needs repotting. For best growth, the plant should be moved to a pot that has a diameter 1 to 1 1/2 inches larger than the one it is presently growing in.

Cover your work area with newspapers. Prepare the new pot with a layer of potting soil at the bottom that is deep enough to hold the plant at the desired height. Place your hand over the old pot with the plant extending between your fingers. Turn it over and gently knock the root ball out of the pot. Place the plant in the larger pot then pour potting soil around the root ball. Tamp or firm the soil gently with your finger tips as you fill the pot. Cover the root ball to the same depth it was previously. Leave 1 to 1 1/2 inches of pot rim above the soil to facilitate watering. Water thoroughly. Place the plant in a low-light area for a few days, then return it to its normal location. Do not apply any houseplant food for several weeks as the new potting soil will meet the plants needs.

8. Q. I have enjoyed impatiens in my garden all summer. How an I grow them in my house during the winter?

A. Impatiens, Impatiens wallerana, can easily be enjoyed as a houseplant. Cuttings taken from plants growing in the garden can be rooted in water and potted up for winter enjoyment. The plant may also be purchased already growing as a houseplant. Any soil will do for impatiens plants, as long as it is not highly fertile. Too rich a potting mix will discourage blooming and encourage leggy growth. When grown indoors the plant requires some sun to bloom; an east or west window would provide enough light for good growth and blooming. The New Guinea hybrids require more sun and require a south facing window. The plants will do well in rooms of average temperatures. As the conditions get warmer the plants will need more water. Impatiens have a tendency to get leggy as they grow. When this happens, simply take new cuttings and start over.

9. Q. I have been given a streptocarpus as a gift. How do I care for it?

A. Streptocarpus species, also known as cape primrose, are very attractive flowering plants with their trumpet-shaped flowers and long primroselike leaves. They are related to African violets and require similar care.

Equal parts of good garden soil, granulated peat and sand are a satisfactory soil mixture. They thrive in bright light but not direct sun. Set the pot on a layer of pebbles, and water the pebbles whenever the plant is watered to provide high humidity around the plant.

Water the plant liberally to encourage more flowers while the plant is actively growing, but as blooming diminishes, so should watering. When the plant ceases to bloom, allow the soil to dry almost completely between waterings. Ferilize with a liquid fertilizer every two weeks while the plant is blooming.

10. Q. I have always considered caladiums as outdoor plants but recently saw them for sale as interior pot plants. How useful are they this way? Can I start them from bulbs?

A. No matter what exposure you have, indoors or out, a caladium will be successful. Caladiums have the unique ability of bringing color to areas of sun or deep shade in the garden, but can also thrive in bright indirect light of the home or office. Outdoor colors are strongest when grown in shade. They become bleached in full sun.

Caladiums can be started at anytime of year and will last from seven to eight months. It is usually best to start the tubers at 6 month intervals to insure that the color of mature plants can be maintained year round. To start individual bulbs, place them 1 inch deep in a 6 inch pot filled with a commercial potting mix. An efficient way of starting a large group of tubers is to place them closely in a shallow container from which they will be transplanted to permanent locations in the border. Many varieties require heat to break tuber dormancy prior to planting and growing. Warmth is essential to leaf development; therefore, temperatures around 70 degrees should be maintained in the early growth stages. Once the tubers are up, temperatures may range from the low 60's at night to the mid 80's during the day. Typically, caladium foliage begins to wither after 6-8 months. At this time, withhold watering and allow the foliage to die completely. Tubers can then be dug and the soil removed from them for storing. Place uprooted bulbs in dry peat moss at 55 to 60 degrees for four to five month rest, then start them again as before.

Tubers are generally not available year round and mail order shipping in winter is risky since the tubers are very cold sensitive. Therefore plan ahead and order your tubers for winter use in the fall prior to cold weather.

11. Q. What kinds of fruit trees can I grow indoors?

A. Calamondins, lemons, limes, kumquats, and pomegranates are good choices for indoor gardening and will often bear successions of perfumed flowers and fruit. Citrus and other fruit trees should be given sunny southern or eastern exposure and their soil kept evenly moist. A well-balanced fertilizer should be applied every four to six weeks. Pomegranates, calamondins, and kumquats are the easiest species to grow.

Calamondins (X Citrofortunella mitis). Dark green, dense leathery leaves on dwarf trees. White, sweetly perfumed blossoms. Sour, deep orange-yellow fruits 1 to 2 inches in diameter. Fruiting season late fall through early summer; occasionally, trees are everbearing. Fruits often used for making marmalade. Excellent pot plant.

Dwarf pomegranate (Punica granatum nana). Bright green, delicate narrow leaves. Flowers scarlet, trumpet shaped. Continuous crops of small, orange-red fruits with juicy, edible pulp; slightly more sour than commercial pomegranates. Very easy culture. Nagami kumquat (Fortunella margarita). Small bushy tree. Long, pointed shiny, dark-green leaves. Fragrant white flowers. Prolific yields of sweet fruit, good for preserves or eating fresh. Fruiting season early fall through winter, often longer. I know nothing about plants but would like to have some reliable plants for my light conditions indoors. Can you tell me about plants that I can't kill?

Some people are literally `in the dark' when it comes to plants. If you enjoy the greenery in your home, but have limited sunlight, you might consider growing the following foliage or flowering plants:

  • Cast Iron Plant, (Aspidistra elatior) gets its name from its ability to withstand abuse. However, its long, leathery leaves will be more attractive with good care. Requires moderate temperatures (70 Degrees F by day 50 to 55 degrees at night). Keep soil moderately moist, but not wet, at all times.
  • Chinese Evergreen, (Aglaonema commutatum). The leaves have beautiful silver markings on a dark green background. Although slow growing it is one of the most tolerant plants of adverse conditions. All Aglaonema species prefer warm temperatures (80 to 85 degrees F by day and 62 to 65 at night) and moderately moist soil. They will, however, grow in moderately dry soils.
  • Victoria Table Fern or Silver Leaf Table Fern, (Pteris ensiformis), has irregular forking, silver fronds with wavy green margins. This dwarf is often used in terrariums or in hanging baskets. It requires moderate to warm temperatures and moderately moist soils.
  • Flamingo Flower, (Anthurium x ferrierense). The main attraction is its colorful spathe (flower bract or sheath). The plant will bloom during any season, but more often from February to July. Other Anthruium species are available with red, white or pink spathes. Requires warm temperature and soils should be kept very moist, except in winter when soil should be kept moderately moist.
  • Peace Lily (Spathiphyllum 'Clevelandii'), likes soil with high organic content. Its leaves are sent out from the base of the plant and its spathes or `flowers' resemble a flattened Calla Lily. Normally blooming in the summer and fall, the Peace Lily makes an excellent potted plant for the home. It requires warm temperatures and soil should be very moist at all times.

12. Q. When and how do I make leaf cuttings?

A. Leaf cuttings are used almost exclusively for a few indoor plants. Leaves of most plants will either produce a few roots but no plant, or just decay.

There are several different ways of making leaf cuttings.

  • Whole leaf with petiole (ex. African violet): Detach the leaf and 1/2 inch to 1 1/2 inches of petiole. Insert the lower end of the petiole into the medium. One or more new plants will form at the base of the petiole. The leaf may be severed from the new plants when they have their own roots, and the petiole reused.
  • Whole leaf without petiole (ex. Most Succulents): This is used for plants with sessile leaves, in other words leaves without a petiole. Insert the cutting vertically into the medium. A new plant will form from the axillary bud. The leaf may be removed when the new plant has its own roots.

13. Q. What will 24 hours of light do to my indoor plants?

A. Many plants are grown in office buildings that are lighted for 24 hours. Different plants react differently to this condition. Most foliage plants grow along the equator, where plants get about 12 hours of high intensity light year-round. Many of these plants grow better under 24 hour light than under 12 hour light as the longer light periods enable plants to compensate for the low intensity of artificial light, by absorbing light over a long period. Certain annual bedding plants may receive enough light order to bloom indoors under continuous lighting. Some plants that do particularly well under 24 hour lighting are Swiss cheese plant (Monstera deliciosa), coleus, cissus, schefflera and cacti. Continuous light also speeds up growth of many slow growing, flowering plants like orchids and cacti. In this way, they can be brought to maturity much quicker.

Some plants do well either both 12 and 24 hour days, including philodendrons, Engligh ivy, pothos and dieffenbachia. Under continuous lighting, they tend to keep their lower leaves longer. Spider plant (Chlorophytum spp) grows best with 12 hours of light. Leaf sections (ex. Snake plant): Cut snake plant leaves into two inch sections. Consistently make the lower cut slanted and the upper cut straight so you can tell which is the top. Insert the cutting vertically. Roots will form fairly soon, and eventually a new plant will appear at the base of the cutting. These and other succulent cuttings will rot if kept too moist.

14. Q. Should the pH of potting soil be adjusted? The mix I use contains a lot of peat moss.

A. Many potting mixes are quite acidic (pH 3.5-5.5) because acidic peat is a major component of these mixes. To raise the pH to a level suitable for most plants, dolomite (limestone containing magnesium), calcium carbonate (lime), or calcium hydroxide (hydrated lime) are generally used. A rule of thumb that can be used is the following: add about 8 pounds of dolomite per cubic yard of potting mix to raise the pH by one unit. Twice as much dolomite will not raise the pH by two units as the pH scale is not arithmetic.

Lime is slightly more efficient than dolomite in raising pH. Hydrated lime can be substituted as follows: one teaspoon per gallon of water added to the potting mix sufficiently for thorough moistening will raise the pH by a little more than half a unit. If necessary, you can do this again after two weeks to raise the pH higher. Do not use more than one teaspoon per gallon each time, and be careful to rinse off any of the solution that gets on the plant as it may burn leaves.

Occasionally, the pH of potting mixes can be too high. If the pH is 7.5 or above, you can add about one half of a teaspoon of sulfur to each 6" pot. Sulfur can be applied as a drench or in granular form. Small amounts are available at the drug store.

15. Q. Does the color of light make any difference in how plants grow?

A. Light quality refers to the color or wavelength reaching the plant surface. Sunlight can be broken up by a prism into respective colors of red, orange, yellow, green, blue, indigo, and violet. On a rainy day, raindrops act as tiny prisms and break the sunlight into these colors, producing a rainbow. Red and blue light have the greatest effect on plant growth. Green light is least effective to plants as they reflect green light and absorb none. It is this reflected light that makes them appear green to us. Blue light is primarily responsible for vegetative growth or leaf growth. Red light, when combined with blue light, encourages flowering in plants. Fluorescent light or cool white is high in the blue range of light quality and is used to encourage leafy growth. Such light would be excellent for starting seedlings. Incandescent light is high in the red or orange range, but generally produces too much heat to be a valuable light source. Fluorescent grow lights have a mixture of red and blue colors that attempts to imitate sunlight as closely as possible, but they are costly and generally not of any greater value than regular fluorescent lights.

16. Q. I bought a pothos plant two months ago and am now having a problem with the tips of the leaves turning black. Please let me know how I can stop this.

A. Pothos are sturdy indoor plants for areas of moderate to low light, rarely suffering from insect or disease problems. Therefore, the tips of the leaves turning black is probably due to watering or fertilization problems. Let's look at the possibilities. Pothos need to be grown in a well drained soil mix that is allowed to dry to the touch before watering. Blackening of the leaf margins or tips is a very common response to over watering. Determine the frequency of watering by the feel of the soil rather than the day of the week.

Leaf tip or margin discoloration also occurs if a pothos is grown under severe stress of very dry soil with inadequate watering. In either case, the discoloration may be accompanied by leaves becoming yellow.

If the leaf color is good, except for the blackening of the tips, over fertilization may be the cause. As with other foliage plants grown in containers, pothos can benefit from the application of a liquid fertilizer mixed and applied according to package directions during periods of new growth. Do not fertilize during the winter when the pothos is not actively growing. Excess fertilizer could cause leaf tip discoloration due to the buildup of salts, which are fertilizer residues, in the soil.

If you have fertilized more often than necessary, the first thing to do, of course, is to cut back on the frequency or the amount of fertilization. Leach the excess fertilizer out of the soil so that no further damage will be done. To do this, place the plant in the sink or tub and water it until water flows copiously through the holes in the bottom of the pot. Repeat this watering five or six times over the next few hours. This heavy watering should not cause overwatering problems since the soil is then allowed to dry to the touch before the next regular watering.

17. Q. I have a two year old prayer plant. The oldest leaves have become dry and brown on the edges. What causes this?

A. Prayer plant leaves tend to become brown on the edge as they age, especially when grown in the dry conditions of the typical home. They do well in large terrariums because of the increased humidity in the enclosed area. When grown outside of a terrarium, they will benefit from being placed on a tray of dampened gravel, which will increase the humidity in the surrounding area. In addition to high humidity, prayer plants need filtered sunlight. The leaves will fold at night and open during the day if they are provided proper growing conditions. Remove the older leaves that have become unattractive. This will not harm the plant.

18. Q. I have a large rubber plant that has recently started dropping some lower leaves. The leaves turn yellow with streaks of green before they drop. How can I stop this? Will new leaves come out on the bare lower stem?

A change in location or heavy fertilization can cause the lower leaves of a rubber plant to drop. Rubber plants are sensitive to moves even within a house and will usually drop some leaves when relocated. When the plant becomes accustomed to new light and temperature levels the condition resolves itself. Leaves also drop when the plant is over fertilized. Carefully follow the directions on the label of a water soluble foliage house plant fertilizer. Unless the plant is in full light, discontinue fertilization during winter months when growth is slow.

New leaves will not grow from the bare lower stem. If the plant is unacceptable leggy, you can air layer it by wounding the trunk, wedging the cut open with a toothpick, wrapping it with damp sphagnum moss, and covering the moss with plastic wrap tied firmly in place. When roots appear, cut off the plant below the layer, remove the plastic, and pot it up as a new plant.

An alternative to air layering the plant is to take tip cuttings from the plant and stick them into the same pot to root and fill in the empty space. You can also train pothos or philodendron up the bare trunk to balance the full top.

19. Q: Request for plant recommendations for low light.

A: Spathyphyllum, Dracaena, Aglaonema, Devil's Ivy, Cast Iron Plant, Chinese Evergreen, Heartleaf Philodendron.

20. Q: Can you use mineral oil to polish leaves of house plants?

A: No. It prevents leaves ability to breathe. Wash leaves with warm water and mild soap if you wish. Be sure to cover the pot to prevent soap from entering the soil.

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