Seasonal & Indoor Plants
Please Note: All recommendations are for central Maryland. Time frames shift two weeks earlier in Southern Maryland and the Eastern Shore and two weeks later for Western Maryland. Check publications for further information.
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JANUARY
- Did you receive an amaryllis for the holidays? Keep it in a sunny window. After it is done flowering, the plant will produce leaves. It can be taken outside during the summer and then brought back inside by mid-summer.
Read more about the care of amaryllis in the Winter 2010 issue of the HGIC newsletter.
- You may notice leaf yellowing and leaf drop on some of your houseplants. This is usually a result of low light conditions or over-watering. Most houseplants should be watered only when the top of the growing medium begins to dry out. Cut back or stop fertilizing houseplants unless they are grown under supplemental lighting. Plants that are out-growing their containers can be re-potted into clean containers. Be sure to wash out any fertilizer salt residues from the containers. Use lightweight, well-drained soil less potting mixes containing peat moss, vermiculite and perlite. These mixes contain fertilizers that will meet a houseplant’s nutritional requirements for 2-3 months.
- A variety of pests may attack houseplants. Fungus gnats are small, harmless, black flies that hover around the growing media. They breed in and feed on moist media and can be controlled by allowing the media to dry out between waterings (Read more...). Brown soft scale (photo) is a common insect pest of weeping fig, orchids, scheffeleria, bay laurel and other plants. Spray plants outside on a mild day with registered house plant insecticide, or wipe down affected stems with rubbing alcohol. Always read and follow the label instructions. You may notice pests like aphids (photo), spider mites (photo) and whitefly on plants that you brought in this past fall. Often times it’s best to simply cut off and discard infested parts, rather than attempt to kill pests with an insecticide. See HG 60 IPM Series: Houseplants for more information.
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FEBRUARY
- We have now passed through the darkest part of winter, the days are now longer and the sun is brighter. This is all very good for houseplants. If you notice leaf yellowing and leaf drop on some of your houseplants it is usually a result of the low light conditions combined with over-watering. Most houseplants should be watered only when the top of the growing medium begins to dry out. It is always safer to slightly under-water than to over water houseplants. HG 60
- A variety of pests may attack houseplants. You may notice honeydew, which is a sticky plant sap product secreted by sucking insects such as aphids, brown soft scale and mealy bugs. Plants commonly affected are ficus, schefflera and jade plants. The honeydew is often first noticed as a sticky floor or carpeting under a plant.
- Mealy bugs, appear as white fluffy masses on infested plants (photo.) They can be controlled by swabbing them with rubbing alcohol or taking plants outside and spraying with a labeled houseplant insecticide. However, don’t do this on a very cold day, or your plants will be damaged.
- Mealy bugs and scales often become an overwhelming problem and it is best to discard extremely infested plants before the pests spread to your other plants.
- Several species of soft scale insects appear as brown bumps on leaves (photo) and stems and can be controlled with a light horticultural oil labeled for houseplants.
- Raising humidity levels around plants and reducing dust levels can control spider mites. Repeated washing of the leaves with water will help in reducing a spider mite problem. (Learn more...)
- Fungus gnats are small, harmless black flies that hover around many houseplants. They breed in and feed in overly wet growing media. Severe infestations result in root rots and size reduction. They can be prevented by being careful not to over-water houseplants. Growing media should be allowed to dry out (but do not allow media to shrink away from the sides of the pot) before watering again. (HG 26)
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MARCH
- Now that the days are getting longer and brighter, it is a good time to begin re-potting and dividing houseplants that are outgrowing their containers. Don’t jump pot sizes from a small pot to a very large pot. Move up to the next size pot. Moving to a too large sized pot will make the plant much more prone to over watering damage. Do not use garden soil, use lightweight soilless potting mixes containing peat moss, vermiculite and perlite. Many of these mixes also contain fertilizers that will meet a houseplant’s nutritional requirements for 2-3 months. If you are not repotting, as new growth appears, resume fertilizing houseplants on a monthly basis.
- If a houseplant is already in a very large container and you cannot move it up to a larger one, you can remove the plant and prune its roots. Fill the outside with fresh potting medium. Pruning some of the roots may set the plant back a little but it will recover and it will have more space for the roots and improve pot drainage.
- A variety of pests may attack houseplants. (HG 60) You may notice honeydew, a sticky substance secreted by sucking insects, feeding most commonly on ficus, scheffelera and jade plants. Mealy bugs (photo) which appear as white fluffy masses are perhaps the most common houseplant insect pest. Other common houseplant insect pests that produce honeydew are the soft scales (photo.) These can be controlled with a light horticultural oil labeled for houseplants.
- Most houseplant insect pests are tenacious and repeated applications of control products are usually needed to get good control. In extreme infestations it is best to simply dispose of the plant.
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APRIL
- This is a good time to re-pot and divide houseplants. Use lightweight, well-drained soil less potting mixes containing peat moss, vermiculite and perlite. These mixes usually contain fertilizers that will meet a houseplant’s nutritional requirements for 2-3 months. When new growth appears with the coming of spring, it’s a good idea to resume fertilizing houseplants on a monthly basis.
- Many gardeners like to move their houseplants outdoors for the summer. Most tropical plants do very well outdoors. But, don’t move your plants directly from indoors out into the direct hot sun. The hot sun will damage the foliage and may even kill the entire plant. Instead, move them into a semi shaded location. April is still a little early to leave them out overnight because many parts of Maryland still get frost in April. Very often pest problems like scale and spider mites are controlled when the plants are moved outdoors. The native predators and parasites will move in and help manage them for you.
- A variety of insects may attack houseplants. You may notice honeydew, which is plant sap secreted by sucking insects feeding on ficus, scheffelera and jade plants. This may be caused by mealy bugs which appear as white fluffy masses on infested plants. They can be controlled by swabbing the mealy bugs with rubbing alcohol or taking plants outside and spraying with a labeled horticultural oil. (HG 60)
- Soft scales may also produce noticeable honeydew and can be controlled with a light horticultural oil labeled for houseplants. Spider mites can be controlled by raising humidity levels around plants and reducing dust levels. There are also labeled house plant sprays that will help kill the mites.
- Fungus gnats are small, harmless black flies that hover around, breed in and feed on moist growing media. They can be controlled by being careful not to over-water houseplants. Growing media should be allowed to dry out before watering again. Learn more...
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MAY
- Most houseplants benefit from being moved outdoors for the summer. Do not move them directly into the sun or they will be badly burned or killed. Move them to a shady location to help acclimate them to outdoor conditions. After a few weeks outdoors those that can tolerate full sun such as palms and banana plants may be moved to the sun. For a uniquely pleasing combination combine houseplants with flowering annuals in container plantings.
- This is a good time to take and root stem and leaf cuttings and to re-pot plants that are out-growing their containers. Be careful not to over-water houseplants. Growing media should be allowed to dry out between watering. Begin fertilizing houseplants again once you notice them putting on new growth.
- When repotting plants, avoid overly large containers. Plants roots often drown because of the large amount of water held by the greater volume of growing medium. High quality artificial mixes contain peat moss, vermiculite and perlite and should be used for re-potting. Do not use soil from the garden for your houseplants. It will not drain properly.
- Fungus gnats are small, black insects that hover around plants. They breed in and feed on moist media and can be controlled by allowing the growing media to dry out between waterings. Placing an inch of sand on the surface of the potting media will discourage fungus gnats. Monitor houseplants for mealy bug, spider mites, aphids, whitefly and thrips. If spider mites are a problem consider spraying with a labeled horticultural oil or soap and pyrethrum mix. If the plants are large do your spraying outdoors.
- Low light is a common cause of houseplant failure indoors. Some recommended plants for low-light conditions include Chinese evergreen, peace lily, snake plant and various types of dracaena.
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JUNE
- This is a good time to root stem and leaf cuttings and to re-pot plants that are out-growing their containers. Re-pot into clean containers and be sure to wash out any fertilizer salt residues. Use lightweight, well-drained soil less potting mixes that contain peat moss and perlite.
- Begin fertilizing houseplants now that they are actively growing again.
- Monitor houseplants that are outside for insect problems. Hose them down regularly if you notice spider mite feeding.
- Fungus gnats are small, black insects that hover around plants. Prevent this problem by allowing your growing media to dry out between watering.
- If you want to take your houseplants outdoors, keep houseplants out of full-sun locations until they are fully acclimated to outdoor conditions.
- Houseplants can be combined with flowering annuals in container plantings.
- Most houseplants should be watered only when the top of the growing medium begins to dry out.
- Badly diseased or infested plants should simply be cut back and the damaged portions thrown out.
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JULY
- This is a good time to take and root stem and leaf cuttings from vigorously growing house plants. The bright days of summer provide ideal conditions for rapid plant growth and rooting of cuttings.
- It is also a good time to re-pot and divide houseplants. Be sure to wash out any fertilizer salt residues from the pots. Use lightweight, well-drained soil less potting mixes containing peat moss, and perlite. These ready-made mixes contain fertilizers that will meet a houseplant’s nutritional requirements for 2-3 months.
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AUGUST
- Now is still a good time to repot houseplants that are potbound. Cut the pot bound root ball with a sharp knife at 2-4 inch intervals and remove any brown, dead roots. Repot into larger containers that have been cleaned of any fertilizer salt residues (white crust on pots). Use lightweight, well-drained soil less potting mixes. Tamp down the potting soil and water frequently. Continue fertilizing houseplants indoors and outdoors.
- If houseplants are outdoors keep them well watered to avoid heat and dryness damage to the roots. Plants kept indoors do not require as much watering.
- Continue to monitor houseplants kept indoors for mealy bug, spider mites, aphids, whitefly and scale. If spider mites are a problem consider spraying with a labeled horticultural oil or soap and pyrethrum mix. If the plants are large do your spraying outdoors. Houseplants kept outdoors usually have few pest problem because they are growing so well and the predators and parasites outdoors keep the pests under control.
SEPTEMBER
- Gradually start to get your houseplants ready to bring back into the house by inspecting for disease and insect problems. If the plants have out- grown their pots repot them into the next size pot or remove them, trim back the roots and repot in the same container. Some houseplants such as ficus, once brought indoors will drop some leaves and slow their growth, as they become adjusted to low light conditions indoors. Be careful not to over water them indoors during this adjustment period which can take several weeks.
- Use lightweight, well-drained soil- less potting mixes. Contrary to old established practice, pebbles, stones, and shards from clay pots do not need to be added to the bottom of planting containers. This actually creates a higher water table and may reduce plant growth. When repotting, cut the root ball with a sharp knife at 2-4 inch intervals and remove brown, dead roots.
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OCTOBER
- If you have not already done so, it is time to bring houseplants back into the house. Check plants for ants, earwigs (photo), pillbugs (photo) and other nuisance insects. Wash off insect pests or apply a labeled houseplant insecticide to control any plant pests such as aphids, scales, spider mites and mealybugs.
- To reduce shock from the change of light, place newly moved plants indoors in a bright location and keep them on the dry side until they have fully acclimated to the lower light intensities of the indoors. It usually takes a few weeks to get a plant reacclimated to being back indoors.
- This is a good time to take and root, stem and leaf cuttings from vigorously growing houseplants. Place the cuttings in a soilless mix such as peat moss and perlite. Keep the cuttings moist but not soaking wet and place them in a brightly lit location or under florescent lights.
- If your African violet has become leggy cut the rosette off near the soil, leaving a 2-3 inch stem. Repot into clean, moist potting soil, cover with a plastic bag sealed at the top and place the pot in diffused light. In about six weeks, new roots will form.
- Potted begonias and geraniums can be cut back and brought indoors.
- Monitor houseplants for mealy bug, spider mites, aphids and whiteflies.
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NOVEMBER
- Be careful not to over-water houseplants. Potting soil should be allowed to dry out between watering. Unless your indoor plants are growing under optimum, high light conditions do not fertilize them during the winter months.
- If your African violet has become leggy cut the rosette off, leaving a 2-3 inch stem. Repot into clean, moist potting soil, cover with a plastic bag sealed at the top and place the pot in diffused light. In about six weeks, new roots will form. A fluorescent shop light with ‘cool white’ tubes is excellent for growing African violets if you do not have good natural light. Call us for more information.
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DECEMBER
- Winter is a challenging time for most houseplants because of the lower natural light and susceptibility to over watering. Be careful not to over-water houseplants. Growing media should be allowed to dry out between watering.
- Unless your indoor plants are growing under optimum, high light conditions do not fertilize them during the winter months.
- To keep holiday plants looking good longer, keep them away from dry, drafty locations. Do not place near heat vents, doorways or drafty windows. Increase humidity around plants by placing them on a tray lined with pebbles, shallowly filled with water. Make sure the water does not enter the drainage holes. For information on caring for Poinsettias, go to HG 30.
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