Ornamental Horticulture

Light

House plants are normally shade loving plants. Bright, but diffused light in a balcony or near a window also is a shady place and darkish corner on the staircase is also a shady place. What the shade loving plants need is bright-diffused light and not the dark places. Most shade loving plants will thrive if tender direct sunlight is available to them in early mornings or in the evenings. In open spaces too, where bright sunlight is available, the shade loving plants can be grown, but under shade nets or under coloured plastic sheets.

The environment in our homes dictates which plants will grow vigorously and which will suffer. The most important environmental factor in growing plants indoors is adequate light. Light provides the energy source needed for plants to manufacture food. The amount of light is commonly measured in lux. The interior of a well-lighted home is often less than 1000 lux, while outdoor light intensity on a clear sunny day may exceed 1,00,000 lux. Plants differ greatly in their light intensity requirements.

Classification of indoor plants based on light requirements:
Based on the amount of light required for growth, indoor plants are often classified as follows.



S.No.	Category	Light requirement (lux)		Common examples
		Minimum requirement	Requirement for good growth
1.	Low	750	1,000 - 2,000	Peace lily Heart-leaf philodendron Cast-iron plant
2.	Medium	1,000 - 1,500	2,000 - 5,000	African violet Boston fern Dumb cane
3.	High	1,500 - 5,000	5000 - 10000	Weeping fig English ivy Schefflera
4.	Very high	10000	10000+	Hibiscus Rex begonia Geranium


In general, the minimum light availability should be about 1000 lux for 12 hours per day to maintain plant quality in indoor plants.



Positioning / placement of indoor plants to suit light requirements



S.No.	Category	Suitable places
1.	Low	In northern exposures Several feet away from eastern exposures.
2.	Medium	Eastern exposures Within several feet of the light sources
3.	High	Near windows / glass doors with western / southern exposures
4.	Very high	In sunrooms / greenhouses




The amount of light at any given location will vary according to time of year (angle of the sun, day length), outdoor tree shading, window curtains and wall color (light reflection) as well as the location itself.



Artificial lighting:


Artificial lighting is widely used to supplement or replace natural light. Many indoor plants grow well under artificial light provided by fluorescent lamps or special incandescent lights. A large variety of fluorescent lamps are available. Generally, ordinary incandescent lamps are not recommended for plants, as plants placed under them tend to stretch or become “leggy.” It is possible to make up for lack of sufficient light by increasing the time or duration that the plant is exposed to light. Sixteen hours of light and eight hours of darkness are satisfactory for most plants. An electric timer can be used to ensure the correct cycle each day.



Harms of inaccurate lighting of indoor plants:


While lack of sufficient light results in poor plant growth, too much light can also be harmful. Shade plants cannot tolerate excessively high light levels. When a plant receives too much direct light the leaves bleach or scald, finally leading to death of the plant. This often happens after moving a plant outdoors in direct light. Any changes in light intensity should be gradual.



Light requirements of some common indoor plants:
A. Low Light (1000 lux)



Botanical Name	Common Name
Aglaonema commutatum	Silver evergreen
Aglaonema commutatum cv. Silver King	Silver king evergreen
Aglaonema modestum	Chinese evergreen
Aspidistra elatior	Cast-iron plant
Aspidistra elatior cv. Variegata	Variegated cast-iron plant
Chamaedorea elegans	Parlour palm
Epipremnum aureum	Golden pothos
Epipremnum aureum cv. Marble Queen	Marble queen pothos
Monstera deliciosa	Split-leaf philodendron
Sansevieria trifasciata	Snake plant
Sansevieria trifasciata cv. Laurentii	Sansevieria


Medium light (1000 to 1500 lux)


Botanical Name	Common Name
Aechmea fasciata	Silver vase
Asparagus densiflorus cv. Myers	Plume asparagus
Asparagus densiflorus cv. Sprengeri	Sprengeri asparagus
Asparagus setaceus	Fern asparagus
Aucuba japonica cv. Variegata	Gold-dust plant
Brassaia actinophylla	Schefflera
Brassaia arboricola	Dwarf schefflera
Caryota mitis	Fishtail palm
Chamaedorea erumpens	Bamboo plant
Chlorophytum comosum cv. Variegatum	Spider plant
Cissus rhombifolia	Grape ivy
Dieffenbachia amoena	Giant dumbcane
Dieffenbachia maculate	Spotted dumbcane
Dizygotheca elegantissima	False aralia
Dracaena deremensis cv. Warneckii	Striped dracaena
Dracaena fragrans cv. Massangeana	Corn plant
Dracaena godseffiana	Gold-dust dracaena
Dracaena marginata	Red-margined dracaena
Dracaena sanderana	Ribbon plant
Fatsia japonica	Japanese fatsia
Ficus benjamina	Weeping fig
Ficus elastica cv. Decora	India rubber plant
Ficus lyrata	Fiddle-leaf fig
Ficus retusa	Indian laurel
Gynura aurantiaca	Velvet plant
Hedera helix and cultivars	English ivy
Howea forsterana	Kentia palm
Maranta leuconeura cv. Erythroneura	Red-veined prayer plant
Nephrolepsis exatata cv. Bostoniensis	Boston fern
Peperomia caperata	Emerald ripple peperomia
Peperomia obtusifolia	Oval-leaf peperomia
Philodendron bipennifolium	Fiddle-leaf philodendron
Philodendron scandens subsp. oxycardium	Heart-leaf philodendron
Philodendron selloum	Tree philodendron
Pilea cadierei	Aluminum plant
Pilea involucrata	Friendship plant
Plectranthus australis	Swedish ivy
Polyscias balfouriana cv. Marginata	Variegated aralia
Saintpaulia species, hybrids and cultivars	African violet
Spathiphyllum spp	Peace lily
Syngonium podophyllum	Syngonium
Tradescantia fluminensis	Inch plant
Zebrina pendula	Wandering jew


High light (1500 to 10000 lux)


Botanical Name	Common Name
Aloe barbadensis	Aloe vera
Alternanthera ficoidea	Joseph’s coat
Aphelandra squarrosa	Zebra plant
Araucaria heterophylla	Norfolk island pine
Beaucarnea recurvata	Ponytail palm
Cissus antarctica	Kangaroo vine
Citrofortunella mitis	Calamondin orange
Coffea arabica	Coffee
Coleus blumei	Coleus
Cordyline terminalis	Ti plant
Crassula argentea	Jade plant
Hibiscus rosa-sinensis	Chinese hibiscus
Hoya carnosa	Wax plant
Iresine lindenii	Blood leaf iresine
Podocarpus gracilior	Weeping pododarpus
Polyscias fruticosa	Aralia
Rhoeo spathacea	Moses-in-the-cradle
Schlumbergera cv. Bridgesii	Christmas cactus
Sedum morganianum	Sedum