Arbor Day is celebrated each year on the last Friday in April. Arbor Day is a national observance that promotes the planting and care of trees. Go ahead and plant a tree!

• Passover — Passover is an eight day Jewish holiday that celebrates the delivery of the Jews from bondage in Egypt. This year Passover is celebrated from sunset on April 18 to nightfall on April 25
• Easter — This Christian holiday celebrates the resurrection of Jesus Christ, and this year falls on April 24.

Patriots Day — Patriots Day is a state holiday in Massachusetts and Maine, marking the anniversary of the battles of Lexington and Concord on April 19, 1775. Patriot’ Day is celebrated on the third Monday in April. The day is celebrated with historical re-enactments and the running of the Boston Marathon.

April 10-16 is National Library Week!

“National Library Week is a national observance sponsored by the American Library Association (ALA) and libraries across the country each April. It is a time to celebrate the contributions of our nation’s libraries and librarians and to promote library use and support.” During National Library Week, libraries across Massachusetts will be celebrating with various events, including Massachusetts Library Snap Shot Day on April 13th. On Library Snap Shot Day, libraries will visually document one day in the life of their library. Images from participating libraries will be compiled and shared to provide a wide-ranging look at public, academic and school libraries in Massachusetts. If you have not visited your library lately, stop in and see what it has to offer. If you love your library, support it in any way that you can.

American Public Library Project — A photo exhibit of public libraries across the country by San Francisco photographer, Robert Dawson (on display at the San Francisco Public Library, April-June, 2011).

I Love Libraries — The American Library Association Web site for library advocacy.

Let them Eat Cake… — Scott Turow discusses the value of libraries and the ongoing threats to their existence in this Huffington Post Op Ed piece.

Share your Library Story in 17 syllables and 140 characters — Take the library “twaiku” challenge and let everyone know why you love libraries.

National Garden Month — The official site of the National Gardening Association and the “Web’s largest and most respected array of gardening content for consumers and educators,” offers news, events, expert advice, a community forum, how-to videos and much more.

Garden Ideas — This site has lots of advice and ideas for experienced and fledgling gardeners alike, including plant selection, suggestions for garden designs, and more.

Successful Container Gardens — How to create and cultivate a healthy container garden from the University of Illinois Extension.

Urban Gardens: unlimited thinking for limited spaces — A hip blog with lots of ideas for creating a garden in a small and/or urban space.

Vegetable Gardening Ideas — Another blog chock full of tips and ideas for growing all sorts of vegetables.

bostongardens.com — A listing of upcoming gardening and garden-related events in the Boston area.

Massachusetts Gardens — “A Treasury of Public and Private Gardens for Garden Lovers to Visit” in Massachusetts.

Gardening Book List — This list of books will provide information and inspiration for both neophyte gardeners and green thumbs.

World Health Day was established by the World Health Organization (WHO) in 1950 and is celebrated each year on April 7th. Each year’s celebration focuses on a different, globally-important health issue. On World Health Day 2011, the WHO will “launch a worldwide campaign to safeguard [life-saving] medicines for future generations” by highlighting the global threat of antimicrobial resistance, which mitigate the effectiveness of medications.

This year’s theme: “No action today, no cure tomorrow.”

World Health Day — The official Web site for World Health Day featuring current news, resources, down-loadable posters, and more.

World Health Day, April 7th : Antimicrobial Resistance — An informative slide show describing the significance of the growing resistance to antibiotics, this year’s World Health Day theme.

Super Drugs and Super Bugs — This book list focuses on epidemics that have wreaked havoc throughout history, those that we may face in the future and the increasing concerns about drug-resistance microorganisms.

World Health News — “an online news digest from the Center for Health Communication at the Harvard School of Public Health. The site covers critical public health issues from around the world.”

Global Health Council — The Global Health Council promotes action on global health issues of all kinds. Their Web site includes a wealth of information and resources on significant health issues.