1. Feeding Bonsai
March 13, David Johnson

2. Plants’ Food Sources
Air: absorption of air (carbon dioxide) plus water produce sugars and starches for the plant through photosynthesis
* As bonsai growers only we can augment food supply (in addition to any nitrogen created by passing lightening storms).
* We do this by directly fertilizing our trees.

3. What We have to Know on the Fertilizer Bottle or Bag
Reading the numbers:
For Evergreens and other acidic loving plants like azaleas:
* : 30% Nitrogen % Phosphorus % Potassium
*Secondary nutrients like calcium and sulphur
* Micronutrients or Trace Elements like iron, zinc, manganese, copper, boron

4. Functions of Primary Elements
Nitrogen: plant growth
Phosphorus: root growth, flower and fruit growth
Potassium: improves water intake of roots, stalk strength, insect resistance, winter hardiness

5. Evergreens and acid loving plants 30 - 10 - 10

6. Deciduous Trees –

7. For Fruiting and Flowering Trees – High Phosphorus 5 – 10 – 5 or 5 – 30 – 5 or – 2 or Bone Meal

8. All Trees: Fish Emulsion (Must ask for the Wildlife’s Permission First)

9. All Trees: Fertilizer Pellets

10. All Trees: Kelp

11. Indoor Bonsai Schultz Liquid Plant Food in eye dropper bottle 10-15-10
follow instructions: 7 drops per liter of water. Fertilize every 2-3 days. Observe plant reaction.

12. Newly Transplanted Trees: High Phosphorus 10 – 52 – 10 for root growth

13. Stressed Trees

14. Stressed Bonsai Artists: 86.6 U.S. Proof

15. Organic and Synthetic Fertilizers
Organics: greater soil retension, slower release of minerals for plant use, more diluted amounts (can lead to more refined growth), less able to burn roots, doesn’t work below 15 degrees Celcius
Synthetics: less soil retension, quick release of minerals, more concentrated amount (over doses can burn plant roots, lead to rapid plant growth)
Many growers use a combination of both. Others prefer organic fertilizers. It helps to change fertilizer manufacturers in order to get a better range of secondary and micro nutrients.

16. Some Do’s and Don’t’s
Don’t apply usual fertilizers until a month after repotting or use transplant fertilizers only
Don’t apply when soil is dry. Water first.
Don’t apply to unhealthy trees. Will increase stress.
Follow the ratio amounts of fertilize to water on the packaging. Sometimes they even give different ratios for potted plants vs. plants in the ground.

17. THINK, ACT AND OBSERVE Learning by rote doesn’t work in long run.
Have a logical plan based on what you want to do with each specific tree combined with your horticultural knowledge and experience.
Act on your plan.
Observe the trees for the results after fertilizing: does the tree look healthier, did the foliage become too large, did the internodes increase, did the foliage discolor?

18. Application: Fertilize according to plans for tree
Trees that you want to grow out, fertilize heavily during entire growing season especially young trees but keep in mind even seedlings and cuttings may grow too quickly by producing long internodes.
Fertilize according to species for example Japanese black pines are heavily fertilized in the spring because the candles will be removed in early summer and fertilization stops until late summer and early fall. Could also apply to trees you plan to defoliate.
There is an ongoing discussion about the pros and cons of minimizing spring and summer fertilizer in favour of fertilizing in late summer and early fall to reduce internodes and leaf size. Could be many variables (weather, soil, watering…) could affect the results.

19. Fall fertilizers are available which have no or lower nitrogen in order to avoid new tender growth that would die off during the winter.

20. Fertilization Timing: late summer-early autumn: When organics shut down at 15 degrees Celcius.

21. Some suggestions for using a minimal spring/summer fertilization approach with heavier late summer/fall fertilization.
Trees in development: heavy spring, summer and fall fertilization
Finished or nearly finished bonsai: light spring and summer fertilization; heavy late summer and fall fertilization.
Exceptions for finished or nearly finished bonsai, trees where new spring foliage to be removed such as Japanese Black pine and Austrian pine and deciduous trees slated for defoliation. After these trees are defoliated, stop fertilization until late summer and fall.

22. FINIS