4/15/2020 – The hibiscus plants along the electrical panel wall were bitten very hard by the winter’s freezes. All above-ground stems were killed and snapped off a few days ago. But, there are small leaves coming up from the stump area and so we need to feed them well.
A link on the home page to here provided the guidance for what we did. The basis of the advice is: They need: Lots of Potassium; Very Little Phosphorus; Medium Amounts of Nitrogen. “The ratio we have found to be the best is the one we use in our HVH Special Blend Fertilizer: 17-5-24. This is the fertilizer we developed for our own hibiscus, after much trial and error. You don’t need this exact ratio, but you do need this pattern of Medium Nitrogen (N) – Low Phosphorus (P) – High Potassium (K).“
Note the Low Phosphorus…therefore, NO Super Bloom!!!
Also “Make sure you find a formula that includes at a minimum copper, magnesium, and iron in a soluble or chelated form.“
Fertilize – Similar advice from a Houston Chronicle Article from a grower in Houston.
This elixir will jump-start your hibiscus in spring: Dissolve 1 tablespoon each of a balanced water-soluble fertilizer (Peter’s 20-20-20), Epsom salts and KNO3 (potassium nitrate) in 1 gallon water. Do not use more than 1 tablespoon of KNO3 or you could burn your plants. Apply again in fall.
For good growth through the season, apply a granular or water-soluble hibiscus food every two weeks in the spring, summer and fall. For extra benefits, foliar feed with a water-soluble fertilizer such as Space City (18-10-28) or Peter’s.
Apply Epsom salts at a rate of 1 tablespoon per gallon of pot size, or throw a healthy handful around grounded plants once a month. Epsom salts can be added to the water-soluble fertilizer and used as a soil drench or a foliar spray.
What we did.
- Blended 1 gallon of 15-0-15 with a heaping cup of 0-0-64 to achieve about the ratios of HVN’s NPK. Pulled mulch back and sprinkled some around each plant. Those amounts were calculated as follows: 0.15 x 1 gal + 0.64 x Needed-Potassium = 0.24. Solving for the Needed-Potassium = 0.14 gal or 1.1 Cups of 0-0-64 to add to the gallon of 15-0-15 to give us 15-0-24.
- Mixed 1 Tbsp chelated iron and 1 Tbsp Epson Salts in 1 gallon of water and put 1/2 gallon around each plant.