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INDOOR PLANTS: CONTAINERS

  MG Manual Reference
Ch. 9, pp. 13 - 18


There are many types of containers from which to choose. A good container should be large enough to provide room for soil and roots, have sufficient head room for proper watering, provide bottom drainage, and be attractive without competing with the plant it holds. Headroom is the space between the soil level and the top of the pot that allows for watering a plant. Containers may be fabricated of ceramics, plastic, fiberglass, wood, aluminum, copper, brass, and many other materials.
Clay and Ceramic Containers
Unglazed and glazed porous clay pots with drainage holes are widely used. Ornate containers are often nothing but an outer shell to cover the plain clay pot. Clay pots absorb and lose moisture through their walls. Frequently the greatest accumulation of roots is next to the walls of the clay pot, because moisture and nutrients accumulate in the clay pores. Although easily broken, clay pots provide excellent aeration for plant roots and are considered by some to be the healthiest type of container for a plant.
Ceramic pots are usually glazed on the outside, some-times also on the inside. They are frequently designed without drainage holes. This necessitates careful watering practices and does not allow for leaching. Small novelty containers have little room for soil and roots and are largely ornamental. They should be avoided. It should be noted that putting pot chips, clay pot shards or gravel in the bottom of a pot does not improve soil drainage; they only provide a small space beneath the soil where some excess water can drain inside the pot.
Plastic and Fiberglass Containers
Plastic and fiberglass containers are usually quite light and easy to handle. They have become popular in recent years because they are relatively inexpensive and often quite attractive in shape and color. Plastic pots are easy to sterilize or clean for reuse, and because they are not porous, they need less frequent watering and tend to accumulate fewer salts.
Roots
REPOTTINGTop

Actively growing indoor plants need repotting from time to time. This occurs very rarely with some slower-growing plants, more frequently with others. Foliage plants require repotting when their roots have filled the pot and are growing out the bottom of the pot.
Hold Upside Down
When repotting becomes necessary, it should be done without delay. The pot selected for repotting should be no more than 2 inches larger in diameter than the pot the plant is currently growing in; should have at least one drainage hole; may be either clay, ceramic, or plastic; and must be clean. Wash soluble salts from clay pots with water and a scrub brush, and wash all pots in a solution of 1 part liquid bleach to 9 parts water.
Cut and Unwind Roots
Don't Pack Soil
Potting media should be coarse enough to allow good drainage, yet have sufficient water retention capabilities. Most plants are removed easily from their pot if the pot is held upside-down while knocking the lip of the container sharply upon the edge of a table. Hold your hand over the soil, straddling the plant between the fore and middle fingers while knocking it out of its present container.
Potting media should be moistened before repotting begins. To repot, place drainage material in the bottom of the pot with some new soil. If the plant has become root-bound it will be necessary to cut and unwind any roots that circle the plant, otherwise the roots will never develop normally. If the old soil surface has accumulated salts, the top inch should be removed. Set the rootball in the middle of the new soil. Fill soil around the sides between the rootball and pot. Do not add soil above the original level on the rootball, unless the roots are exposed or it has been necessary to remove some of the surface soil. Do not pack the soil; to firm or settle it, tap the pot on a level surface or gently press the soil with your fingers.
Leave Room
Grow Bushier
Leggy plant needs to grow bushier, keep more compact form.

Pinch
Pinch out growing tip of tallest stem, removing it close to the leaf point.

Bushy
New growth forms just below pinched-out tip, makes plant bushy.
After watering and settling, the soil level should be sufficiently below the level of the pot to leave head-room. A properly potted plant has enough headroom to allow water to wash through the soil to thoroughly moisten it.
TRAINING AND GROOMINGTop

This includes a number of minor care activities that distinguish the beginner from the more experienced indoor plant grower. Pinching is one of them. Pinching is the removal of 1 inch or less of new stem and leaf growth, just above a node. This leaves the plant attractive and stimulates new growth. It can be a one-time or continuous activity, depending on the need and the desires of the plant owner. If a plant should be kept compact, but well-filled out, frequent pinching will achieve this.
Pruning is a similar activity. Pruning includes removal of other than terminal shoot tips. Sometimes an entire branch or section of a plant should be removed for the sake of appearance.
Disbudding is another related care activity. Certain flower buds are removed either to obtain larger blooms from a few choice buds or to prevent flowering of a very young plant (or recently rooted cutting) that should not bear the physical drain of flowering early.
Ivies and hoya, as well as philodendron and syngonium, are frequently grown in a formal pattern. This can be easily achieved by training them on trellises. It is important to keep plants clean and neat. It not only improves the appearance of plants but reduces the incidence of insects and disease problems. Remove all spent flowers, dying leaves, and dead branches. Keep leaves dust-free by washing plants with warm water and mild soap (cover pot to prevent soap from entering the soil). If tips of leaves become brown and dry, trim them off neatly with sharp scissors. Removal of alkali deposits at the soil surface and replacement with clean soil does more for appearance than for the plant itself.
CARE OF SPECIAL POTTED PLANTSTop

Too little light, excessive heat, and improper watering are the usual causes of failure in caring for gift plants. These plants are grown in a greenhouse, where the night temperatures are usually cool, there is ample light, and the air is moist. When they are brought into a dry home, where the light is poor and the temperatures are maintained for human comfort, results are frequently disappointing. Do not expect to keep a gift plant from year to year. Enjoy them while they are attractive and in-season and then discard.
Poinsettia
The poinsettia requires bright light and should be kept away from drafts. A temperature between 65 and 70º F. is ideal. Avoid temperatures below 60º and above 75º. Keep plants well- watered but do not overwater. Some of the newer, long-lasting varieties can be kept attractive all winter.
Gardeners frequently ask whether they can carry their poinsettias over to bloom again next year. It is question-able whether the results are worth the effort, as the quality of home-grown plants seldom equals that of commercially grown plants. However, for those who wish to try, the following procedure can be followed.
After the bracts fade or fall, set the plants where they will receive indirect light and temperatures around 55 to 60º. Water sparingly during this time, just enough to keep the stems from shriveling. Cut the plants back to within 5 inches of the ground and re-pot in fresh soil. As soon as new growth begins, place in a well-lighted window. After danger of frost, place the pot outdoors in a partially shaded spot. Pinch the new growth back to get a plant with several stems. Do not pinch after September 1st. About Labor Day, or as soon as the nights are cool, bring the plant indoors. Continue to grow in a sunny room with a night temperature of about 65º.
Since the poinsettia blooms only during short days, exclude artificial light, either by covering with a light-proof box each evening or placing in an unlighted room or closet for a minimum of 12 hours of darkness. Plants require full light in the daytime, so be sure to return them to a sunny window. Start the short-day treatment in mid-September to have blooms between December 1 and Christmas.
Azaleas
Azaleas require direct sunlight to remain healthy. A night temperature of 60º will prolong bloom. Keep the soil constantly moist. If the leaves should turn yellow, the soil is not acid enough. Use an acid fertilizer sold especially for azaleas. Do not use softened water. When repotting, use a mixture high in acid peat moss.
Azaleas can be planted, pot and all, in a shady spot in the garden during the summer months. Examine them frequently and keep them watered during dry periods. Greenhouse azaleas are not hardy, and need to be brought indoors before freezing weather.
Azaleas need a cool, rest treatment before they are forced into bloom. Place the plants in a room with filtered light and a temperature between 35-50º F. During this rest period, flower buds will develop. Then place in a well-lighted, warm (65º F.) room around January 1 to bring them into bloom. Unless you have the proper growing conditions for the azalea, you should not attempt to carry the plants over.
Gardenia
Gardenias grown indoors need special care. They demand an acid soil and should receive the same nutritional care as azaleas. The night temperature should be near 60º and the humidity around the plant should be kept high. High temperature and low light intensity will result in flower bud drop.
Amaryllis
The secret of growing amaryllis is to keep the plants actively growing after they finish blooming. Keep the plants in full sun, with a night temperature above 60º. As soon as danger of frost has passed, set the plants in the garden in a semi-shaded spot. In the fall, before danger of frost, bring them in, stop watering them to allow old growth to die back, and store them in a cool, dark place to rest. They will be ready to force again about November 1. Bring them into a warm light room and water moderately to begin new growth.
Christmas Cactus
The Christmas cactus has become increasingly popular with the development of several new varieties. At least three related species are sold in addition to a number of cultivars. All have similar cultural requirements.
The secret of good bloom seems to be one of temperature and photoperiod control. They will develop buds and bloom if given bright light, short days, and night temperatures between 55 and 65º F. Christmas cacti bloom best when somewhat pot-bound, repotting is necessary only during midwinter, but bright sun during summer months can make plants look pale and yellow.
Christmas cacti require less water from October to March than they do when growth is active from April to September. A rest period is very important if plants are to bloom abundantly. Dormancy should be started about the middle of September and continued for 8 weeks. Care should be taken that soil never becomes water-logged during the dark days of winter.
Cyclamen
Cyclamen require full sunlight and a night temperature of between 50 and 60º. They are heavy users of water and must be watered whenever the surface of the soil is dry. Flower buds will fail to develop if night temperature is too high or if light is poor. Cyclamen can be carried over, but as with the poinsettia, homegrown plants are seldom equal to those grown by a commercial grower. Let the plants die down after they finish flowering. Repot the fleshy corm in June with the top of the corm above the soil line. Allow resting bulbs to dry, but not to become shrivelled.



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