Air Plants
   Offers growing and care advice for tillandsias: watering, lighting, fertilizing, mounting, propagation and FAQ.
   http://plants.web-indexes.com/

All About Houseplants
   Collection of articles, tips, and links on basic houseplant care.
   http://www.all-about-houseplants.com/

AllExperts House Plants
   Offers answers to reader-submitted questions. Includes reader's ratings and comments.
   http://www.allexperts.com/browse.cgi?catLvl=3&catID=721

Avflower.com
   Grower of gesneriads and succulents in Belarus offers personal articles and photo galleries of African violets, streptocarpus, and adeniums. Site in Russian/English/French.
   http://avflower.com/

Caring for Flowering and Foliage House Plants - The Garden Helper
   Offers information on topics including dish gardens, terrariums, indoor topiaries, repotting, pests and toxic plants. Includes a glossary, botanical names and guides to individual species.
   http://www.thegardenhelper.com/houseplants.html

Fia's Pelargoniums
   Offers information on raising pelargoniums in an apartment. Includes photographs.
   http://hem.bredband.net/pelargonsidan/

Garden Web House Plants Forum
   Offers a discussion forum. Topics include care, selection and sources.
   http://forums2.gardenweb.com/forums/houseplt/

Gardenline House Plants
   Offers growing and care advice from the University of Saskatchewan. Includes growing from seeds, humidity, using pure water as well as detailed information for several specific plants.
   http://gardenline.usask.ca/plants/index.html

Guide to Selecting Houseplants - NebGuide
   Provides information for selecting plants based on environmental conditions. Includes a list of plants and their general requirements.
   http://www.ianrpubs.unl.edu/epublic/pages/index.jsp?what=publicationD&publicationId=236

HPlants.com
   Personal website offers care information and photos on a handful of commonly grown houseplants.
   http://www.hplants.com

House Plants
   Offers information on air-cleaning and poisonous plants. Includes details toxicity and risks.
   http://www.blankees.com/house/plants/

House Plants: Proper Care and Problem Solving
   Offers information about cultural considerations. Includes trouble signs and common infectious diseases.
   http://www.ag.ndsu.edu/pubs/plantsci/landscap/pp744w.htm

Houseplant Hydroculture
   Guide to growing houseplants without the use of soil: materials, nutrients, plant care, and FAQs.
   http://www.hydro-culture.net/

Houseplants - University of Illinois Extension
   Offers information on topics including needs, selection, care, health and propagation. Includes types by botanical and common name and by light requirements.
   http://www.urbanext.uiuc.edu/houseplants/

I Can Garden Houseplants
   Offers feature articles. Topics include repotting, seasonal tips, checking seeds and non-toxic pesticides.
   http://www.icangarden.com/document.cfm?task=viewcategory&categoryid=37

Indoor Gardening - Insects/Diseases
   Offers articles, news and briefs from the University of Minnesota Extension Service. Topics include bacterial leaf diseases, powdery mildew and root rot.
   http://www3.extension.umn.edu/topics.html?topic=5&subtopic=163

Indoor Jungle
   Offers techniques and feature articles on topics such as moss poles, winter problems and life spans. Includes FAQ, a photo gallery and a discussion forum.
   http://www.wayswriter.com/indoorjungle/

Indoor Plants - Terrariums
   Offers tips on growing in transparent glass or plastic. Topics include containers, soil, placement and care.
   http://hgic.clemson.edu/factsheets/HGIC1457.htm

Interior Plantscaping with Large Houseplants
   Offers instructions for massing green foliage indoors. Includes selections by lighting and problem diagnostics.
   http://www.ag.ndsu.edu/pubs/plantsci/landscap/h1123w.htm

Misc-Houseplant-Exchange
   Offers a discussion board for trading house plants. Includes some issue discussions.
   http://groups.yahoo.com/group/misc-houseplant-exchange/

Muttart Conservatory: Passionflower Factsheet
   Brief information and care instructions for these tropical vining plants, with emphasis on their use as houseplants. [PDF]
   http://www.edmonton.ca/ArtCultAttr/Passionflower.pdf

My Hoyas
   Includes photographs and descriptions of the author's hoya collection. [English, Swedish]
   http://www.myhoyas.com

PlantCare.com
   Offers a database of over 2,000 species and genera of indoor plants. Includes common pests, photographs and a bulletin board. Paid subscription required for some information.
   http://www.plantcare.com

PlantOasis.com
   Guide to houseplants, featuring a directory of common species with basic information and a photo for each, articles about care and culture, and Q&A.
   http://plantoasis.com/

PlantSpecs
   Offers planting, light, temperature and propagation information. Includes search by photo, scientific or common name.
   http://www.plantspecs.com

Poinsettia Care in the Home - Ohio State University Extension
   Offers information on watering, light, temperature and reflowering.
   http://ohioline.osu.edu/hyg-fact/1000/1248.html

Potted Plants
   Offers information on identification and care. Includes articles on indoor bulb gardens, bonsai and safety. From Virginia Cooperative Extension.
   http://www.ext.vt.edu/cgi-bin/WebObjects/Docs.woa/wa/getcat?cat=ir-ln-ig-pp

Spaths.com
   Offers information about growing the Peace Lilly indoors. Includes care, varieties and FAQ.
   http://www.spaths.com/

University of Illinois Extension: Poinsettia Pages
   Poinsettia history, facts, and care, including instructions for reflowering.
   http://www.urbanext.uiuc.edu/poinsettia/index.html