8/3/2021 – Had 0.4″ of rain late yesterday so the soil was very damp. Checked the pH at 8 locations and got the following pH readings.
| Side | 3-4′ from side of base | 6-10′ from side of base |
|---|---|---|
| East | 4.8 | 5.1 |
| North | 4.5 | 5.1 |
| West | 4.5 | 4.8 |
| South | 4.8 | 5.0* |
| Average = | 4.8 |
The tree has many limbs with few leaves and some dead limbs. We thought it was due to herbicide used on the grass last year. Clearly, the very acidic soil is a problem.
Various Advice:
- The ideal pH for the banana magnolia ranges from a minimum of 6.1 to a maximum of 6.5. …the root zone extends from the trunk a distance that is equal to about four times the width of the canopy. From SFGate.
- Soil pH: 6.0 – 6.5 (Moderately Acid to Slightly Acid) – Wilson Bro’s Gardens
The Plan
Need to raise the pH from the average of 4.8 to 6.25 or 1.45 points, but be careful and not all at one time.
From center of base to drip line is 10 ft. to 12 ft. depending on the side. Given that the root zone extends well beyond the drip line and the desire to be conservative with this first pelletized liming, we will spread the lime 10′ beyond the drip line. That means we will spread over a 20′ radius circle that is theoretically 1,257 SF. Note that a portion of that area is covered by the concrete paver walkway with its 6-inch thick crushed lime base and the flower beds of the west and east sides. The walkway at 5 ft wide and roughly 40 ft across the circle is 200 SF. The beds are over 100 SF so very roughly we need to cover 1,000 SF.
The Fix – Phase 1 of 3
Spread 40 lbs of Austinville Pelletized lime on the grass areas inside a 20′ radius circle. Based on the table from the bag (see image below) that is about one-third of what is needed. Plan to spread another 40 lbs in 30 days.; then 40 more 60 days later (i.e. 90 days after the first application) provided there are no negative signs.
