Not all soils are created equal. A soil test is often required to see what your garden's soil fertility is like. Doing a soil test is an inexpensive way of ensuring the flowers in your garden are getting the nutrients they need during the growing season, and it allows you to make adjustments if they aren't.
A soil test is best performed in late October or early November to get the soil when it is not stressed from the summer growing season. But if pressed, a soil analysis can be done at any time in the year.
Samples of soil should be taken from different sections of the garden, especially in areas where the soil texture or color changes from a previously sampled section. Samples should also be taken from areas in the garden that have poor or no growth, or where plants often die.
Taking a Sample
Samples can be dug up using a small hand trowel or spade. Thin, vertical slices of the soil should be taken. If the area of the garden you are sampling is small, a few slices will do, but if the area is larger, many may be necessary to determine the soil quality. For flowers, the top 6 to 8 inches of soil should be sampled. Place soil slices from each distinct area into a clean plastic container or bag and label it.
Soil samples should be sent to a garden center local university so the composition and pH can be tested. Soil composition will let you know whether it is mainly composed of sand, silt or clay, while a pH test will tell you what nutrients are present, what is lacking, if there are any toxic elements to the soil or if lime is required to balance the acidity for your plants.
Home pH tests can be purchased if a local testing service is unavailable or too expensive; pH testing meters can be purchased from local gardening centers. To test with a pH tester, the soil needs to be dug into so that 2 or 3 inches is removed and watered--then the pH probe will be stuck into the dirt. The pH will be measured, above 7 is alkaline soil, and below 7 is acidic soil.