Control Release Fertilizer, when to re-apply

[The Warm Canuck]

My control release fertilizer pellets, says to apply every 4 months. However, I still have a bunch of it still sitting on the top of my pots. Does this need to be completely dissolved before re-applying, or should I just re-apply as per the package directions?

 

[August44]

What brand are you using? Some brands look like they are still there but what you see are empty hulls.

 

[Shibui]

If it is really controlled release fert - little colored balls - then what's left is probably just empty shells. The nutrients leach out through the shell leaving it intact but with no more nutrient soon after the timing says.
Another type is compounded slow release fert which works differently.

Controlled release fert like osmocote works when it is wet so spread on the surface is the least efficient way to apply as the balls are mostly dry and not working. There may still even be some nutrient left as surface application messes with the proper release. Best application is to dig holes in the soil and fill with the balls - dibbling.

You can definitely add more controlled release fert after the release time has elapsed. Spring is high nutrient use for trees so timing is good for a new dose. You haven't mentioned what species and whether the trees are indoors or outdoors. Species and location will influence whether nutrients are needed all year or only in the growing season.

 

[The Warm Canuck]

If it is really controlled release fert - little colored balls - then what's left is probably just empty shells. The nutrients leach out through the shell leaving it intact but with no more nutrient soon after the timing says.
Another type is compounded slow release fert which works differently.

Controlled release fert like osmocote works when it is wet so spread on the surface is the least efficient way to apply as the balls are mostly dry and not working. There may still even be some nutrient left as surface application messes with the proper release. Best application is to dig holes in the soil and fill with the balls - dibbling.

You can definitely add more controlled release fert after the release time has elapsed. Spring is high nutrient use for trees so timing is good for a new dose. You haven't mentioned what species and whether the trees are indoors or outdoors. Species and location will influence whether nutrients are needed all year or only in the growing season.

I am referring to Osmocote. I use it on all my outdoor conifers and deciduous in development. I also use it on my indoor tropicals.

I have only been sprinkeling it on top of the substrate. I'll start digging it in, as you have said, well, and as the bottle instructions also detail ..haha