Springtime Plant Nutrition

 

Proper timing and judicious use of the right kind of fertilizer is essential for healthy growth of plants. 

Nitrogen is most in demand right now and it is often lacking in our local soils, so it must be supplemented through applications of fertilizer.  Moderate amounts of a well-balanced fertilizer (
10-10-10) favor a more desirable growth rate without over-stimulating the plant.

Quick sources of nitrogen (such as ammonium sulfate and ammonium nitrate) are relatively inexpensive and easy to use, but be careful not to overdo it.  Excessive use of nitrogen fertilizers can cause burn or salt build-up and can also leach into the groundwater supplies.  Slow-release fertilizers (such as urea) provide for even growth without the risk of burning, they don't require frequent re-applications, and they pose less risk to the environment. 

Organic compost, manure, and sewage sludge are excellent sources of nutrients, and are especially desirable for their soil conditioning effect.  Always follow package instructions when applying chemical fertilizers.

Vegetable gardens need to have fertilizer tilled into the soil before planting, then applied at intervals throughout the growing season.  Withhold fertilizer once vegetables begin to ripen. 

Citrus and avocado trees recovering from frost damage will require higher amounts of nitrogen fertilizer and ample water.

Feed flowering shrubs once they have finished blooming.  Acid-loving plants such as azaleas and camellias need an acid-type fertilizer for optimum growth and appearance.  Begin roses, annuals, perennials, and container plants on a monthly feeding schedule for a longer blooming period.  Turf and ground covers do well with 1 pound of nitrogen per 1000 square feet of area.

If you didn't fertilize your dormant fruit and nut trees in February, do so now - one to two pounds of nitrogen per mature tree at the tree's drip line.  Younger trees and dwarf trees use proportionally less.

Excessive amounts of fertilizer can over-stimulate plant growth, contribute to heat stress, and result in leaving the plant more susceptible to diseases and infestations of insect pests, such as aphids, mites, Psyllids, and others.

University of California Cooperative Extension Master Gardener Volunteers can provide additional gardening information upon request .Call the San Luis Obispo office at 781-5939 on Mondays and Thursdays from 1 to 5 PM.  You may also call the Paso Robles office at 237-3100 on Wednesdays from 9 AM to 12 PM.  The San Luis Obispo Master Gardeners website is at http://groups.ucanr.org/slomg/.  Questions can be e-mailed to: mgsanluisobispo@ucdavis.edu.