[this is another Coursera course assignment]

Global warming is happening. As urban dwellers, what can we do to help fight against climate change? One of the many things that we can do to help is green our cities by growing our own organic gardens and organic food – sustainable organic gardening.

Is organic gardening more sustainable than traditional gardening? The answer is, of course, yes. This essay is going to explain the reasons why urban gardening can help fight against global warming and why should we prefer organic gardening over traditional gardening.

Global warming is primarily a problem of too much carbon dioxide (CO2) – the dominant greenhouse gas – in earth’s atmosphere. The CO2-dominant greenhouse gases in the atmosphere act as a heat barrier, blocking heat (thermal radiation) going out of the atmosphere and warming the planet. However, CO2 doesn’t block heat coming to the earth from the sun. CO2 can only absorb at very specific wavelengths and some of these wavelengths happen to be emitted by the earth. The wavelengths emitted by the sun are too short to be absorbed by CO2.

The burning of fossil fuels and clearing of forests to create pastures and plantations has contributed to a 40% increase in the atmospheric concentration of CO2 since the beginning of Industrial Revolution. This increase has been continuing despite the absorption of a large portion of the emissions by various natural CO2 sinks involved in the carbon cycle. Some CO2 is absorbed by the oceans and some is absorbed by plants and soils – organic-rich soils.

Urban gardening will increase the green coverage of the cities and hence increase the ability for absorbing CO2 emissions of the urban areas. Urban gardens include all the small-area and large-area urban gardening practices, for example, back-yard, front-yard, side-yard, rooftop, balcony and container gardens, and community gardens, etc.

Making urban gardens more supportive of biodiversity will make the gardens more sustainable. One good example for the need of biodiversity is to keep bees with us for generations to come, and for sustainable agriculture. Lawns are unnatural habitats, and they can be converted to more natural garden habitats by planting a variety of native vegetation types including vegetables, grasses, flowers, shrubs and trees to attracts beneficial insects and birds. Big and tall trees are our best friends to fight against climate change, and they use our limited land resources more efficiently and they provide shades for other plants so that we can water less.

As the population pressure worsens, urban gardening can play a key role in the sustainability of the future food production. With biodiversity in mind, we can grow fruit trees, vegetables and food crops in our urban gardens with other types of vegetations. Urban food production is an important part of the sustainable local food movement.

Organic gardening will reduce chemical use in many ways. First, organic gardeners don’t use synthetic fertilizers, pesticides, plant growth regulators, genetically modified organisms, etc.; second, organic gardens will make healthier environment and provide healthier food – which also means they’ll make us healthier to reduce medicine (chemical) use; third, organic-rich soils will grow strong plants to compete with weeds and will reduce nutrient (chemical) leaching to pollute water sources, and are more capable of absorbing CO2 – a key factor to fight against global warming.

The following are the main aspects of organic gardening: composting, mulching, crop rotation, ground cover planting, companion planting, water conservation, and no synthetic fertilizers, pesticides, plant growth regulators and genetically modified plants.

For many urban gardeners, traditional gardening is probably easier than organic gardening, especially for new gardeners. However, organic gardening can be easy too once you know more about plants, soil and how to make organic pesticides and herbicides. Moreover, organic gardening is healthier and more sustainable.

Global warming is happening. Let’s green our cities by planting organic urban gardens with biodiversity, and fight against the climate change using our shovels.

I compiled the following list for a Coursera course assignment:

Planning. Don’t hurry your garden projects, do your homework first, so that you know your taste and your sites. If you are a new homeowner, you may want to wait for one year to know your yards better – existing plants, pests, and light, etc. – and start from small gardening projects. Planning includes budget, timing, site selection, garden design and more.

Choosing Plants. Plants may grow fast or slowly; may be difficult to propagate or easily to spread; may or may not bloom; may like cool or hot weather; may require less or more maintenance; etc. Plants that spread quickly may eventually become weeds if you don’t want to have them in your garden any more. Marilyn Lewis of MSN Real Estate lists 12 plants that you may want to avoid to have in your yards.

Reading Labels. A label with seeds or a plant that is for sale usually contains information like annual or perennial, hardiness zones, mature size, spacing requirement, light requirement and watering requirement of the plant. To avoid getting wrong plants for your gardens, you should at least read the labels carefully. Talking to good or professional gardeners, or doing your own research in advance before purchasing will definitely help.

Selecting Sites. Common mistakes with selecting gardening sites include: the soil is not well-drained; the site will get too much or too little sunshine for your plants; or the site or the project is too big.

Maintaining Soil. Common mistakes with soil maintenance include: planting the same crop year after year without crop rotation or companion planting; and tilling soil when it’ss too wet. Planting the same crop year after year damages soil fertility and increases soil-borne diseases and soil-dwelling insects. Working soil that is too wet results in soil compaction.

Planting and Transplanting. Common mistakes with planting or transplanting plants include: planting too deep or too shallow; transplanting without loosing the roots first; planting too early when frosts are still possible or too late when the temperature is too warm or hot for transplanting; transplanting in bright sunshine; and transplanting without thoroughly watering. The best time of a day to transplant is evening.

Overwintering Plants. There are many annual plants can be perennial if you dig them out and keep in warm places during winter time. Keeping them outside in winter will kill them, for example, dahlia.

Watering. Common mistakes with watering include: watering in bright sunshine – it can burn leaves; watering in evening – it can cause fungi, snail and slug problems; and shallow watering – it may encourage a shallow root system. The best time to water plants is early morning.

Pruning. A common misunderstanding is that plants don’t need pruning or pruning will hurt or kill plants. Indeed, for most of trees or bushes, pruning is necessary and will make them healthier and look better. Most of trees or bushes can be pruned in late winter or early spring, some can be pruned any time, but some can only be pruned in summer.

Composting. Making your own compost is not difficult, but it’s not easy either. Some essential mistakes to avoid include: placing compost bins/piles in direct full sun – it can make it too dry to compost; putting diseased plants, weeds’ seeds and seedpods into compost – it may not be hot enough to kill the diseases and seeds; putting meat and bones into compost – it’ll smell and attract pests.

Mowing. One common mistake of mowing is mowing too low. Mowing too low makes your lawn difficult to maintain moisture to keep it healthy. The best time to mow is when it is going to rain.

De-weeding. Leaving weeds’ seeds, seedpods and flowers on your lawn or garden bed may just spread the weeds. If you cut and leave dandelion flowers on your lawn, it’s very likely that they’ll continue to grow and bear seeds, and the seeds will mature and spread.

Fertilizing Lawn. Common mistakes with fertilizing lawns include: not fertilizing at all – grasses need nitrogen to grow to compete with weeds for spaces and nutrition; using wrong fertilizers – you want to use fertilizers that are high with nitrogen and low with phosphate and potassium; fertilizing too much – it’s better to feed less than more; fertilizing when it’s hot and dry – fertilizers can burn your lawn when it’s dry and hot. I once fed my lawn with compost provided by the City of Toronto, and it contained a lot of weeds’ seeds.

Gardening needs time, efforts and patience. Choosing professional landscaping over DIY may not be a good idea because you know your taste the best. With DIY projects and abundant resources and help you can find nowadays, you’ll become a gardening expert of your own garden given time. Do it yourself, and make our world a better and more sustainable world.

I live in Toronto, Canada, and yes, de-weeding is a four-season job for me and it’s fun! Just imagine the fresh air, singing birds, beautiful flowers, organic tomatoes and many more!

I don’t have any favourite sports, so walking is usually my only exercise. I do enjoy walking around my yards and the neighbourhoods where I live and where I work.

My favourite de-weeding tool is a weeding knife. I use it to loose soil around the roots and then pull the weeds out. I always wear a pair of gardening gloves when I de-weed.

Weeds need space, water, light and nutrients to grow. So, if your lawn is healthy, it’ll be difficult for weeds to survive and reproduce. Keeping grass clippings on your lawn is one easy way to keep your lawn healthy.

You can walk on your lawn and pull out weeds when you see them if the lawn is NOT frozen, covered by snow or too web. Here is what can be done for de-weeding in the four seasons:

1. Early spring: lightly fertilize your lawn once; de-weed (over-winter weeds are easy to be seen).
   
2. Spring to late summer: de-weed; don’t let weeds set and drop seeds; get rid of weed flowers, seed pods, and seeds from your lawn, don’t put them into your compost unless you are sure the composting process will generate enough heat to kill them.
   
3. Early fall: lightly fertilize your lawn once if the lawn is healthy, otherwise, fertilize heavily; de-weed; don’t let weeds set and drop seeds.
   
4. Late fall to early winter: de-weed if the lawn is workable.
   

Coursera offers many free online courses related to climate change, energy, food, agriculture, animals and plants etc. taught by world-class professors and fabulous professionals.

Education is a key to sustainable development. Distance education is more environmentally friendly than traditional class-room education. Coursera provides a platform that can reach every corner of the world where Internet is available. People from all over the world get educated and share their ideas through Coursera.

Here are some examples of courses offered at Coursera:

  * Energy, the Environment, and Our Future
  * Sustainable Agricultural Land Management
  * What a Plant Knows (and other things you didn’t know about plants)
  * Sustainability of Food Systems: A Global Life Cycle Perspective
  * Introduction to Sustainability
  * Economic Issues, Food & You

Fall is a good time to buy discounted garden containers. There are a few good reasons why do you want to use containers even if you have enough garden space in your backyard:

• Containers are easier to tend
  You can raise your containers for easier handling and move containers for sunshine, shade, airflow and space. When night temperatures drop, you can also move containers indoor.
  
• Some plants do better in containers
  Plants don’t do well because of short growing season or too much rain and not enough sun. However, in containers, heat-loving plants like eggplants and peppers can thrive regardless of nature’s whims.
  
• Container plants often suffer less pest attacks
  Container-grown plants generally suffer less pest attacks because they live in a cleaner and more frequently inspected environment.
  

There are two important things should be kept in mind:

• Soil
  Make your own compost or ask around where do other organic garden growers get compost and what do they get. Check ingredients if you buy mix or soil because you don’t want any synthetic fertilizers. If you use self-watering contains, you don’t want any additives to increase water retention either. Some basic ingredients in a mix are: sphagnum peat, limestone, vermiculite, and/or perlite.
• Watering
  Container plants usually require more often watering. If you buy or make self-watering containers, make sure they don’t have holes and hidden places that attract mosquitoes and slugs.

The taste of fresh-picked home-grown organic vegetables is even better than that of what you can buy. Not to mention the satisfaction of “working” outside, enjoying fresh air, bright sunshine and a great sense of achievement. Planned correctly, the most basic vegetable gardens take little time or effort.

Location

If you can find a piece of well-drained land in your yard that can get full sun (eight to ten hours daily at the pick of summer time) or at least six hours of sun daily, grow your own organic vegetable garden may not be as difficult as you think.

Preparation

The best time to till your garden is in the spring. You should till your garden at least once, maybe twice a year. The soil has to be dry enough before you till. To see if your soil is dry enough, pick up a hand full and squeeze it in your hand. If the ball of soil in your hand falls apart when poked, the soil is dry enough. To prepare the soil for planting, you can use a garden fork and cultivator to loosen the surface soil, then use the garden fork again or a deep spading fork to loosen the subsoil.

Compost is necessary for your organic garden. Compost can be used as a top dressing or mixed with the soil. You can buy or get free compost from your community, you can even make your own compost.

Planning your garden is important. You need to leave paths to work your garden beds / rows and keep in mind that air circulation is also important for your plants.

Planting

If you want to start from seeds, you may have to to plant seeds indoor six to eight weeks before the last frost. Check local stores for seed starters. Buying seedlings is usually easier.

Following instructions when plant seeds and transplant seedlings.

Caring

Plants need nutrition, water, sunlight, air circulation and temperature to thrive. Feeding, hoeing, weeding, watering, protecting and supporting are a list of things that you may need to do to take care of your garden.

Water is the most important resource on Earth. Without water we could not live. According to Water.org, 884 million people lack access to safe water supplies; approximately one in eight people.

• Reduce running water use :
  Don’t run the tap for cold water – use ice cubes or keep a jug of water in the refrigerator. Never leave the tap running when washing vegetables or dishes, shaving, or brushing your teeth. Use tubs or plug the sink if you can.
• Fix leaks, stop drips :
  Check regularly for any leaks around taps and faucets and repair promptly.
• Collect rainwater, reuse greywater :
  Collect rainwater and chemical-free fruit and vegetable washing water for your indoor plants and garden. Reuse greywater whenever you can.
• Choose native plants :
  Plant trees, shrubs and herbs that are native and generally require less care and water.
• Water and mow lawns wisely :
  Water lawns and gardens no more than once a week in the early morning or late evening to reduce evaporation. Don’t cut lawns too short and leave the grass clippings on the lawn to keep moisture and feed the grass.
• Broom driveways :
  Use a broom, not a hose, to clean driveways and walkways.
• Use water-saving shower heads :
  Water-saving shower heads can cut water use by 40%.
• Protect water sources :
  Don’t pour chemicals down drains, or flush drugs down toilets; it could come back in diluted form in your water.

General-purpose computation on graphics processing units (GPGPU) is the technique of using GPUs, which typically handle computation for computer graphics, to perform data-parallel computation in applications traditionally handled by CPUs.
The latest NVIDIA GPU (Tesla M2050 / M2070) can provide computing power of a CPU cluster at 1/20th the power consumption and 1/10th of the cost. A single GPU can reach the peak double precision floating point performance of 515 Gflops, and the peak single precision floating point performance of 1.03 Tflops.

Here are a few environmental gardening tips I use to green my own garden.

• Make your own green pesticide
  1) Combine one teaspoon dishwashing liquid and one cup vegetable oil and shake vigorously to let mix well. 2) At ten-day intervals or more often if needed, combine eight teaspoons of the mixture and one quart water and spray.
  ( 1 quart = 4 cups = 64 tablespoons = 192 teaspoons = 0.946352946 liters )
• Make your own green pesticide (2)
  You may want to open the windows before start this process. Take 12 heads of garlic and boil them for an hour in a large pot of water. Allow the mixture to cool, then strain into a simple spray bottle and use it on plants afflicted with aphids and white flies.
• Stop slugs and snails from eating your favourite plants
  Copper wire carries a small electrical charge that is harmless to people and pets but acts as a deterrent to slugs and snails in a garden. Simply make a loop of copper wire on the ground around the bottom of your plants.
• Put up a bird house
  Invite a natural predator into your backyard. A common wren will eat thousands of insects and caterpillars all summer. This can completely eliminate the need to use chemical insecticides.
• Making your own compost
  It is a simple task that is not only good for your lawn but also helps cut down on waste. You can make your own compost by taking vegetable or fruit scraps, such as the peeled skin from a carrot, potato, apple, etc. These work well and also give your lawn great nutrients that they wouldn’t get elsewhere.
• Water in the evening
  This can enhance your water conserving efforts when it comes to gardening such as seriously cutting back on watering times, only watering at strategic times of day (such as in the evening).
• Mulch throughout your garden
  This is not only a beautiful way to enhance the look of your garden but it also provides a natural way to save water by less need to water and protects plants as well.
• Prune trees and shrubs
  Some trees and shrubs need pruning to maintain health and vigor. Pruning and removing dead branches can encourage healthy growth and increase foliage. You can find pruning techniques and timing on the Internet.

Trees, shrubs, herbs, flowers, grasses and other plants are nature’s air purifiers. They constantly clean the air and reduce the air pollution. Plants in your home or office are not only decorative, but also air purifiers. Here is a list of popular and highly effective indoor plants that homeowners and office dwellers can have as living air purifiers:

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Plant Name	Ability to remove chemicals (out of 10)	Lighting conditions	Notes
$item->name ($item->sci_name)	$item->ability_air	$item->lighting	$item->grow_note