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What Phosphorus is Right For Your Bulbs?

By on September 27, 2012

Find out why Tricia is smiling at a box of Seabird Guano! Hint: it has to do with the numbers on the front.

Why do we plant bulbs? So they’ll bloom! What makes bulbs bloom? Phosphorus.

Phosphorus is the P in the N-P-K numbers on fertilizers.

Phosphorus is a little bit sneaky though—and we’ll teach you the tricks to get the phosphorus to your bulbs.

Phosphorus stays put

We all add nitrogen fertilizers to the surface of our soil, and nitrogen moves through the soil, reaching the roots. Phosphorus doesn’t move, so add it near the roots at planting time. Mix in a powdered phosphorus soil amendment or fertilizer at the bottom of your planting hole.

Which source of phosphorus should you add? Keep reading.

Acid or alkaline soil

Test the pH of the soil where you’ll be planting bulbs. The pH ranges from 1 (most acid) to 7 (neutral) to 14 (most alkaline). It is likely that your soil is in the 5 to 8.5 range.

Here comes the chemistry: the pH of your soil affects how chemicals react. Bone meal is a good source of phosphorus, as is soft rock phosphate, but the nutrient can only be accessed in acid soil. In the photo above, Tricia is adding bone meal to her slightly acid Sierra foothills soil.

If you have alkaline soil, use Hi P Seabird Guano, or Hi P Bat Guano for phosphorus. That’s why Tricia is smiling at the Seabird Guano box—there’s a high phosphorus number on the front, and it’s phosphorus that will work in alkaline soil.

Tips for bulb planting

See all of Tricia’s tips on how to plant bulbs in our video.

Plant bulbs in the fall (with the right kind of phosphorus) and guarantee yourself a flower-filled spring!

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