Blackberries are a popular garden fruit for home gardeners in mild climates throughout the United States. Their sweet, juicy fruit appears mid- to late summer and is used for fresh eating, baking and preserves. Blackberries are a bit particular about their watering needs--too much and they rot, too little and they wilt. Providing good soil and watching them closely will keep them healthy.
Blackberries don't tolerate waterlogged soils, including heavy clay soils or soils prone to flooding or standing water. Additionally, blackberries require at least 1 inch of water weekly to perform well.
Waterlogged blackberries slowly wither and lose leaves. They die either from lack of oxygen or from root diseases, according to Oregon State University. Blackberries that receive insufficient water, either before or during harvest, produce smaller and fewer blackberries, as well as smaller and less abundant canes.
Blackberries should be planted in well-drained, loamy soil, according to North Carolina State University. Clay soils don't drain well or allow aeration. Sandy soils drain too quickly, drying plants out. Soils should be amended with plenty of organic material, such as compost, before planting. Raised beds may also improve soil quality and drainage. Provide additional irrigation to blackberries during dry weather or high winds to keep the soil evenly moist. Organic mulches may also help conserve moisture and benefit the soil.
Soaker hoses or a trickling hose work well for several reasons. Less moisture is lost through evaporation than when using sprinklers, and leaf and fruit diseases are minimized by keeping the plants dry, according to North Carolina State University. When identifying blackberry problems, consider the presence of disease, sunscald, nutrient deficiencies and cold temperatures as possible causes, as well as lack of water.
Blackberries thrive in mild, moist climates, such as the southern United States and the Pacific Northwest. Some varieties are hardy to USDA plant hardiness zone 5, but may produce fewer and smaller berries in cold climates. Raspberries are more cold hardy and may be a good substitute in dry, cold areas.