Here's a breakdown of what you need to know regarding feeding and watering Ligustrum plants...
Feeding Ligustrum Plants
Ligustrum will benefit from fertilization. Fertilize them in spring with a slow-release shrub & tree food, preferably one that contains Sulfur and/or Iron. Alternatively, you can feed with a natural organic plant food. To avoid stimulating new growth that could be damaged by an early frost, cease fertilization two weeks prior to the average first frost date in your area.
Soil pH
Soil pH is a measurement of the alkalinity or acidity of soil, which is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline.
Ligustrum grow best in a moderately acid to moderately alkaline soil ranging from 6.0 to 8.0 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0.
If you're unsure about the pH of your soil, or whether or not it's suitable for growing Ligustrum, it's a good idea to test the soil pH in the planting area. You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil Sulfur, Aluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.
Watering Ligustrum Plants
When young, Ligustrum will require some water to establish roots. When established most varieties are exceptionally drought tolerant. As with so many other ornamental plants, they will not tolerate constantly soggy or wet soil conditions, which can lead to root rot and other harmful plant diseases. So be careful to avoid overwatering them!
At Planting Time
Immediately after planting deep soak the soil in the planting area, including the rootball, to a depth equal to the height of the root ball. For an extra boost, you can water your newly planted Ligustrum with a solution of Root Stimulator, which stimulates early root formation and stronger root development. Root Stimulator reduces plant shock and promotes greener, more vigorous plants.
During the First Active Growth Season
In average garden soil you should not have to water your newly planted Ligustrum every day. More often than not, this causes soggy soil conditions that can lead to root rot and other harmful plant diseases. In the absence of sufficient rainfall, water only as needed to keep the rootball and surrounding soil damp to moist. Keep in mind that deep soaking less frequently, allowing the soil to dry out somewhat before watering again, is much better than splashing just a little water on the plants every day. Shrubs planted during the winter dormant season, when plants are not actively growing and evaporation is much slower, will require much less water. Therefore, be extra careful not to overwater during winter!
Thereafter
Only during prolonged drought will established Ligustrum plants require supplemental irrigation. If you see new leaves wilting or the tips of new stems bending over during dry weather this could be a sign your plants could use a good deep soaking.
TIP: When watering with an automated irrigation system it's best to set your timer to water during the early morning hours and not in the late evening or at night, which can lead to the onset of fungus and other foliage diseases. During the first few weeks after planting, check soil moisture often and adjust irrigation time if necessary to keep the soil moist, not wet.