Gardentalk – How to choose and use fertilizers

Fertilizer spreader
Fertilizer spreader awaits its first use of the season on a North Douglas lawn that also needs some thatching. (Photo by Matt Miller/KTOO)

Not all fertilizers are the same. Some balanced mixtures of nitrogen, phosphorus and potassium may be used interchangeably for annuals, perennials or even a grass lawn.

“There are some that we can kind of get away with very often so that we don’t have 27 bags, boxes or buckets stashed in our shed either solidifying in the moisture or otherwise,” says Master Gardener Ed Buyarski.

But other fertilizers may be formulated specifically for bulbs, particular vegetables like tomatoes, or your grass lawn after its root health has rebounded from winter dormancy.

Buyarski provided a primer on fertilizer and fertilizing techniques during this week’s segment of Gardentalk on KTOO’s Morning Edition. He advises gardeners to read the back of the package for the N-P-K numbers or breakdown of the fertilizer mix.

“That is mandatory labeling to tell the customer what it is they are getting. For lawns, you start out in the springtime with something like an 8-32-16 or 10-20-20. But then in the summertime for green grass growth, then it’s a high first number, very often 20, or 20 percent nitrogen and 5 percent phosphorus and 5 percent potassium. In the springtime, we’re trying to grow good roots and in the summertime we’re trying to grow more grass.”

Many vegetables may take a balanced fertilizer mix of 10-10-10.

10-12-10
Back of bag of 10-12-10 plant fertilizer specifies proportions of nitrogen, phosphate, and potash. (Photo by Matt Miller/KTOO)

Fertilizing spikes can be pounded in around a shrub or tree’s root system, granular or powdered fertilizer can be diluted while watering hanging plants or your greenhouse vegetables, and grass fertilizer should be distributed evenly with a lawn spreader.

Another key tip, says Buyarski, is don’t just fertilize once and forget. Try half of the recommended amount for the first application and then return to apply the full amount every few weeks. When it comes to fertilizing your lawn, go out with your spreader just before a rain or water your lawn after fertilizing so the dry grass doesn’t get burned and yellow.

Listen to the May 19 segment of Gardentalk about fertilizer:

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