A tool used for removing tile grout also works great. Thick weed blocking fabric from garden catalogs will keep weeds down if you cover it with a layer of bark or stones. Be sure to get the heavy-duty type guaranteed for five years. Choose plants and trees that resist pests and disease. Certain flowering cherry trees are resistant to brown rot.
Some roses are resistant to aphids and mildew.
Certain rhododendrons are resistant to root weevils and are drought tolerant. Nurseries can help you in making choices. Create a safe slug trap instead of using slug bait. Lift it up in the morning and scrape the slugs into soapy water. Surround your prized plants with copper barriers.