Landscapers raise ivy as a vigorous and low-maintenance ground cover or trellising plant, according to the University of Florida. Although the plants are very hardy, they do require occasional irrigation to help them maintain their lush, green foliage. Watering needs vary slightly depending on whether you raise the plants as outdoor specimens or indoor houseplants.
Test the soil's moisture levels. For outdoor ivy plants, use a screwdriver or similar implement to check if the soil is moist at a depth of 6 inches. For indoor plants, insert your finger 2 inches into the potting soil. Watering should be withheld until the soil is dry at these respective levels.
Apply water to the ivy plant's base instead of on its foliage. This reduces the risk of the vine contracting a foliar fungal disease like powdery mildew or blight. Irrigate until water drips out of the pot's bottom drainage holes, according to the American Ivy Society, or until the soil is moist at a depth of 1/2 foot for outdoor plants.
Water again after fertilizing the ivy. The University of Florida recommends fertilizing indoor plants with any standard houseplant fertilizer and outdoor plants with a 15-5-15 or 12-4-8 product. Spread the fertilizer according to its labeled rate, as potency varies by product, then water lightly to help carry the nutrients to the ivy plant's roots.