Salvia plants, often called "sage," are very easy to grow and care for. There are many Salvia species and most will grow well in any average moist to dry, well-drained soil. That said, it's a good idea to know the moisture needs of specific types of Salvia you intend to grow. Some prefer a consistently moist soil while others tolerate a drier soil.
Here's a breakdown of what you need to know regarding feeding and watering Salvia plants...
Feeding Salvia & Sage Plants
Salvias and sages do not require fertilizer, however, will benefit from it. The plants are light feeders, meaning they don't require heavy doses of regular fertilizer. In fact, a 1-inch layer of aged compost applied in spring, covered by another inch of shredded wood mulch or straw mulch, can provide enough nutrients to maintain healthier plants and increased flower production. Alternatively, you can apply a slow-release flower food in spring, make several applications with a mild organic or natural plant food, or feed more frequently with a diluted liquid feed.
Keep in mind salvias and sages receive too much fertilizer or are planted in an overly rich soil, plants can become leggy and stems will often flop over. An additional 2 inches of mulch raked over the soil helps retain moisture and adds additional nutrients as the mulch slowly decomposes over the growing season.
Soil pH can be important. 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.
Salvias and sages grow best in a moderately acid to slightly alkaline soil ranging from 5.5 to 6.5 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 salvias and sages, 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 Salvia & Sage Plants
When established, all salvias and sages are quite drought tolerant. Reason being, they can lose their foliage any time of year if necessary to conserve energy and sustain themselves through a drought. In severe drought conditions salvia plants will usually keep some tiny leaves at the tips of stems in order to carry out photosynthesis to stay alive. Then, when rain or irrigation comes the plants will flush back out. This said, if there's sufficient rainfall or irrigation salvia plants will look nice throughout the growing and flowering season. Sages bloom in late spring to early summer, with intermittent flowering through the whole summer, if irrigation is available.
When you water salvia, water the soil around the plant and try to avoid splashing water on the leaves. It's best to water during the morning hours or during the afternoon so that water can dry from the leaves. Watering any plants in the late evening or at night can cause foliage and other plant plant diseases.
Watering Salvia 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 Salvia 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 Salvia every day. More often than not, this causes soggy soil conditions that can lead to root rot and other 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 is much better than splashing just a little water on the plants every day. Perennials planted during the winter dormant season, when plants are not actively growing and the evaporation process is much slower, will require much less water. So, be extra careful not to overwater during winter!
Thereafter
In the growing season plants will appreciate supplemental irrigation during drought or dry weather. If you see leaves wilting or curling during the growing season this could be an indicator 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 plant diseases. During the first few weeks after planting, check soil moisture often and adjust irrigation time if necessary to keep the soil moist but not constantly wet.