Fertilize During Active Growth

• Bonsai trees generally need to be fed through the spring and into summer/fall, not while dormant or just emerging from dormancy. Growth-active roots and foliage make the fertilizer useful. 

Use Organic or Balanced Fertilizers

• Many experienced growers (including Ryan, especially on conifers like pines) prefer organic or slow-release fertilizers rather than strong chemical ones, because they’re gentler and feed the tree more steadily. 

Timing Matters with Fertilizer and Development Work

• For trees where you want controlled foliage and shorter internodes, timing fertilizer applications before pruning or candle cutting is important:

• Apply fertilizer enough in advance of major pruning so the nutrients have been used and aren’t forcing rapid shoot growth immediately after cutting. 

Plan Multiple Applications

• For spring, it’s common advice in that series and other Ryan talks to give a few applications spaced about 4–6 weeks apart rather than a single dose — this keeps nutrients available throughout the active phase. 

Adjust by Tree Maturity

• Young or vigorous trees often get fed slightly differently than mature ones:

• Developing trees may be fertilized more frequently (to encourage growth).

• Refined bonsai may be fed less to avoid overly vigorous, coarse growth once structure is established. 

Never Fertilize After Repotting

• While this is general bonsai best-practice (and likely mentioned or implied), avoid feeding right after repotting — roots are recovering and fertilizer can stress them.