Tree Planting 101: Part 4 – Fertilization

Tree fertilization is a process that should be administered by an arborist during the tree planting process.  Fertilizing in the planting hole can cause root injury, so we usually wait to fertilize young trees lightly in the spring after planting.  Starter fertilizers are not essential on newly planted trees, however, adding mycorrhizal fungi to the soil can be beneficial because it helps the tree’s root system establish.  Well-rotted compost can be missed in with the dug soil, too, but only if the soil is used to fill in the area around the roots – not below the roots.

Fertilization Do’s and Don’ts:

  • Do not fertilize in the planting hole as it might cause root injury
  • Do fertilize young trees lightly the spring after planting
  • Starter fertilizers are not essential on newly planted trees – the most important part is a wide hole and mulching to keep the tree moist and cool for good conditions for root growth.
  • Fruit trees: lightly mix in fertilizer to backfill after the hole is filled – lightly fork it in.
  • Adding fertilizer should be avoided as it can harm and burn freshly forming roots.  The addition of mycorrhizal fungi to the soil can be beneficial because it helps the tree’s root system establish itself.  This should be mixed in with the soil before backfill is added.
  • Well-rotted compost can be mixed in with the dug soil, so long as the soil is used to fill in around the roots – not below the roots.