Plants don’t occur naturally indoors; but a large proportion of plants can be grown inside a building, if provided with the right conditions.

To be successful with indoor plants, you need to be able firstly, to identify correctly, the plants you are dealing with; and then secondly, understand the conditions required for the specific plant variety concerned.

Click for details on our Indoor Plant Course 
 
Indoor plants are simply plants which we have found to be adaptable to an indoor environment.

Usually an inside environment will differ from an outside one in the following ways:

  • It has lower light intensities
  • It is warmer in winter and cooler in summer
  • In some rooms (e.g. kitchen, bathroom, laundry), humidity can get high
  • The balance of gases in the air is different:  (particularly damaging with gas heaters or air conditioning).
  • While many indoor plants originate in tropical areas, this by no means the case for all.  The natural environment for tropical plants is usually wet, humid and hot.  If those plants are placed in an indoor environment which is cooler and less humid then wetness must also be reduced. 

Over-watering is a common problem with tropical indoor plants being grown in temperate regions.

The best rule is:  use a freely draining soil, water thoroughly once and then do not water again until the soil is absolutely bone dry.  In some situations this might mean watering once very three months, in other situations once a day.  The rate of watering is influenced by factors such as temperature, soil type, humidity and cannot be put down to a regular timetable.  YOU CANNOT SAY "WATER ONCE A WEEK"!

Check Indoor Plant Books at www.acsbookshop.com

 

 

APHELANDRA

Shrubs or clump forming herbs with attractive flowers with large velvety dark green foliage. Long lasting flowers in terminal spikes with large, often very attractive bracts.

Needs ample moisture is important. Fertile deep soils preferred but can be adaptable. Protect from strong winds. Prefers tropical climates and part shade.

A general complete plant fertilisers should be applied every 3 months maximise growth and flowering. Prune after flowering period to encourage vigorous new growth and improved shape. Propagated by semi-hardwood or tip cuttings, or seeds when available.

Pest & Disease: Prone to Chinese rose beetles - use Carbaryl; and thrips - use diazinon or malathion.

Species & Varieties:

Approximately 80 species, including:

  • sinclairiana (Coral Aphelandra) -Tall shrub to 5m with upright coral coloured bracts (pink and orange) borne from summer to autumn. Moderately fast growth rate.
  • squarrosa (Zebra plant) -Striking clumping foliage plant with deep green veins surrounded by white. Bright yellow floral bracts. Requires sunlight in order to flower well. Different named varieties exist with variations in leaf markings.
  • deppeana -Medium shrub with yellow, orange and red flowers.
  • aurantiaca (syn. A. nitens) -Small shrub with yellow and orange flowers, and coloured veined leaves.

 

Genus: ARALIA

Variable including herbs, shrubs & trees. Highly divided delicate leaves. Flowers are small, often insignificant, white or green, arranged in very large heads (umbels).

The Aralia flower heads are generally larger and more spectacular than the closely related Fatsias.

Features: Mainly grown for their ornamental foliage, rhizomes of some species are aromatic and may be used in medicines or cookery.

Requirements fertile moist soils preferred. Best in part sun although they may tolerate full sun.

Prune to control height. Mulching is generally beneficial. Propagate by ripe fresh seed, or cuttings. Variegated plants may be grafted on to green forms.

Pest & Disease: Scale, mealy bug, sooty mould - control when detected only.

Species & Varieties:

Over 30 species, including:

  • chinensis -To 6m tall, spiny foliage
  • cordata (syn. A. edulis) -To 2m tall, white flowers, young shoots are edible if blanched.
  • elata -The most commonly grown species, to 2.5m tall,
  • elata 'Variegata' -Cream margins to the leaves.
  • elata 'Aureo variegata' -Pale yellow leaf variegation.
  • racemosa -A tall, tree like with extremely long serrated leaves, used for architectural contrast in a garden.
  • spinosa (Devil's Walking Stick) -Thorny trunk, clumping shrub or small tree to 10m or more. Stems mostly unbranched with strong prickles. Pinnate leaves 60cm - 1.8m long. Flowers in umbels in very long panicles.

 

 

CALADIUM

Can be difficult in cool or dry climates, but easy to grow in hot humid places. Form spreading clumps, heart shaped leaves on long stalks, foliage colour very variable, Prefers fertile, moist but drained soil, best in protected semi to half shade (not dark), lift tubers and store dry when it dies down over cooler weather Propagate by division of tubers. Most cultivated plants are hybrids or varieties of C. hortulanum which grow in clumps to 0.6m tall varying in leaf colour.

 

CALATHEA

Generally easy in temperate or tropical areas, Clump forming or ground covers, grown for attractive foliage, leaves often shades of purple or red underneath and striped patterns on top, hardy and easy to grow in pots or the open. They need some shade and moist soil, prefer mulching, propagate by division or cuttings.

  • insignis (Rattlesnake Plant) To 1.8m tall, leaves to 0.4m long green with brown markings
  • makoyana (Peacok Plant) To 0.7m tall, Leaves white & green stripes on top
  • ornata To 1m tall, Green leaves with pale pink stripes
  • zebrina (Zebra Plant) To 0.8m tall (often lower), velvet green leaves with darker stripes

 

CODIAEUM (syn. Croton) Family: Euphorbiaceae


Crotons are shrubs with highly coloured plants with upright woody stems. Insignificant flowers borne in summer.

Moist need a fertile soil required. Prefer filtered sun or light shade (too much shade causes loss of leaf colour), keep soil moist in warmer months, leaf drop can result if air or soil becomes too dry (or if exposed to wind), propagate by semi hardwood cuttings.

Will not tolerate extended dry periods.

Pest & Disease: scale, thrips, mealy bugs - use white oil or malathion; Spider mites - use wettable sulphur or miticide.

Species & Varieties:

6 species. Most cultivated plants are from the species variegatum

  • aucubaefolium -Foliage bright green with yellow blotches, from Polynesia.
  • bogoriense -Foliage with yellow variegation on green leaves, from Java.
  • spirale -Twisted leaves with red, yellow and green markings, from Malaysia.
  • variegatum (syn C. pictum) -Variable species in terms of colour and leaf shapes.

To 1.8 metres, many different varieties each having different foliage colours, foliage is more colourful in full sun.

 

COLEUS

Most do best in filtered sunlight, but tolerate full sun or more shade, chewing insects sometimes a problem with non-scented varieties, propagate by cuttings.

  • amboinicus Hardy ground cover, leaves with thyme like scent often used in cooking
  • X blumei Most popularly grown coloured leaved varieties are hybrids of this species, need water, generally upright bushes 0.3-1m tall.
  • carnosus (syn. C. repens) tolerate dry, pungent scented grey-green foliage, repels some dogs & cats
  • spicatus Tolerates dry, minty scented blue green foliage, better in filtered sun, blue flowers

 

 

CORDYLINE

Strap like green or coloured foliage. Cut top out of plants to encourage side shoots and more dense clumping growth habit. Generally hardy and adaptable, some tolerate drought or heavy shade. Propagate seed or cuttings. Varieties:

  • australis -To 5m with bronze and green leaf forms.
  • indivisa To 8 metres, Large clumping plant or "tree"
  • stricta -Dark green foliage plant to 4m.
  • terminalis -Can grow to 4m but usually kept to 2m or less. Dwarf forms are available. highly coloured foliage - pinks, red, purple, yellows, white, etc. Colour tends to improve as the cooler months approach.

Varieties:

Hawaiian Flag -Red stripes on yellow leaves.

Juno -Broad leaves, pale yellow in the centre and pink tipped.

Kiwi -Compact grower, narrow yellow, green and red striped leaves.

Negri -Large leaves, almost black green.

Pink Diamond -Long green leaves with pink leaf stalks, white margin and red edge.

Red Ribbon -Long strap like deep red leaves with light red margin

Red Sister -New growth is bright pinkish red, older leaves are a deep red green.

Tricolor -Distinctive cream, pink and green leaves.

Note: Cordylines are frequently confused with Dracaena. The difference being Cordylines have ovaries with three cells, each with 6-15 ovules. Dracaena have only a solitary ovule in each cell.

 

 

DIEFFENBACHIA

There are many different hybrid varieties with attractive, coloured foliage, needs moist but drained soil, half shade (too much light can reduce colour in foliage), poisonous sap, bruised foliage has an unpleasant scent, needs humidity, stem rots, scale & red spider sometimes, Propagate by cuttings or aerial layers. Commonly grown varieties include: D. X picta Exotica, D. X picta Superba, D. X picta Rudolph Roehrs.

 

 

DRACAENA

Includes both large & small clumping plants/shrubs (over 500 varieties), most tolerate shade. Prune out top to stimulate branching which makes it bushier...but side shoots which develop can become heavy & often break off in storms. Propagate by cuttings or aerial layering. Sometimes damaged by beetles or other insects, excess watering can sometimes cause rot (in cooler weather). Most need high humidity (D. draco and D. godseffiana do well in dry air).

Varieties:

  • deremensis -Upright shrub to 5m tall with green and white stripped 5cm wide leaves.
  • fragrans -To 7m tall but usually pruned to a bushy plant. Green and whitish stripped 10cm wide leaves.
  • surculosa (syn. godseffiana) -To 2m tall with green and white spotted elliptical leaves.
  • marginata -Slender tree to 4m with strap like green pointed leaves with red-purple margins. May be mistaken for D. cincta and concinna.
  • sanderiana -Clump forming plant, to around 0.8m tall, twisted leaves, dense, variegated forms often cultivated.
  • reflexa (syn. Pleomele reflexa) -Branched shrub up to 10m tall with linear leaves. Colour variations are green with cream stripes or yellow stripes.
  • draco -Tall shrub similar in appearance to the succulent Yucca.

 

 

IRESINE

Grown for leaf colour (best in full sun), tolerates shade, prune to control size and keep dense, grow to 0.6m or higher, propagate by cuttings, scale a problem

  • herbstii red leaves
  • herbstii aureoreticulata variegated leaves
  • lindenii red pointed leaves

 

 

PHILODENDRON

There are two types of Philodendron -climbing/sprawling plants; also non climbers, some tolerate lower temperatures but generally best to avoid below 12 degrees celsius, avoid direct sunlight, prefer moist, mulched soil, water freely in lot weather, propagate by cuttings or layers.

Variety

Foliage

 bipinnatifidum

Dark green, divided, very large to 1m

 evansii

Crinkled, to 1m long, light green (NB: P. evansii is

actually a hybrid of P. selloum and P. speciosum)

 selloum

Deeply divided, dark green, wavy edge

 wendlandii

Elongated lanceolate, dark green

 

 

SANSEVIERIA

Good drainage, full to half sun, tolerates some dry periods but not extended drought, propagate by division or leaf cutting, scale insects

Variety

Leaves

Height

 trifasciata

Marbled dark green & grey-green

0.6-1.2m

 trifasciata "Laurentii"

Yellow margin, green centre

to 1m

 

 

 

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