By Ken Whitten
Late March is always a pleasure. The rains are still around, and there are plenty of cool nights, but freezing weather is almost over, the days are lengthening and any sunny afternoon sends us strolling down streets filled with blowing cherry blossoms.
Here and there, a struggling Hebe or a dead Phormium, casualties of the coldest winter in decades, remind us that gardening, like life, is full of uncertainty. The scent of lilacs fills the air, and we take reward for our October foresight in the form of blooming tulips. Then, after a feast of Rhodies and the Sun’s the brief kiss, we put aside poetry, head to the shed, grab our boots and get to work.
This rampant growth takes energy. By the first of April frost-danger recedes and we start to think about feeding our gardens. If you didn’t plant a cover crop, or manure earlier in the year, don’t lament. A good balanced fertilizer, like 5-5-5 or 10-10-10 (Nitrogen, Phosphorous, Potassium, always in that order!) is the perfect Spring pick-me-up for most hardy shrubs.
If you use dry organic fertilizers apply these as early as late March. They are slow-release and take a few weeks to begin working. These organics have the benefit of not burning plants if over-applied, and will not damage roots if mixed into the soil. They work slowly, so they also won’t promote quick bursts of tender growth at a time when there is still some danger of frosts. Prefer to use synthetic fertilizers? Delay your application to mid-April, especially if more than a quarter of the nitrogen in your product is supplied by ammonia, which is very fast acting (quick growth often fares poorly if we freeze…). While you’re preparing your plant banquet, consider giving plantings a micronutrient fertilizer from time to time: trace minerals are the forgotten ingredient in most plant-foods, but their minute presence can yield big results!
Finally, it makes no sense to prepare a feast for your plants if they can’t make use of what you feed them! Most plants absorb nutrients most readily when their soil is slightly acidic to neutral (pH 6.0-7.0). Typical Portland soils, however, are moderately acidic (pH 5.0-5.5). At this acidity, many nutrients are “locked up” – bound chemically to soil components or to one another in a ways that prevent many plants from using them. There are exceptions. Plenty of our Spring superstars are right at home in acidic soils: Rhododendrons, Azaleas, Camellia, Blueberries and Pieris need nothing more than a nice feeding of acid-loving plant food and a bit of mulch to bloom beautifully.
Still, most plants are not acid-lovers. The majority of fruits, flowers, trees, shrubs, roses, veggies and lawns benefit from raising your soil’s pH, and applying lime. Annually is the perfect time to do it. Hydrated and dolomite limes act more rapidly than some cheaper forms and may be worth the expense if you want to see results this spring. Save a little lime for your tomatoes because blossom end-rot on a tomato is a sad, sad thing.
Speaking of sad, remember those unhappy frost-damaged plants mentioned earlier? You may be wondering if a little fertilizer might do them some good as well. Maybe, depending on the plant and what you use. Initially, you might consider giving these plants a starter-type fertilizer (lower nitrogen, slow-release, root encouraging) to provide for base-line nutrition without encouraging quick growth. Some plants may recover fully, losing only a few tips, some will survive and re-emerge from the trunk or roots.
Some, even some that now appear to be alive, will falter and die with the first blast of warm weather, victims of a shattered vascular system. Cest la vie…but hey, that looks like a great place for next Fall’s tulips!