One of the small details you might not be aware of if you use controlled release fertilizers (slow-release) is the length of time they are effective and feed your plants and they operate in two different ways.
Controlled release fertilizers come in two different modes of operation.
- One is controlled by soil moisture so the more you water, the more it breaks down feeding your plants.
- The other is heat related – the hotter the soil temperature, the more it releases its nutrient charge.
This means a hot season such as we’ve had will really cause these products to release quickly – either because of the raw volume of water or the high heat.
Length of Effectiveness
They also come in all lengths of time – from 30 days right up to 180 (a full growing season) After this time, they’re all used up. Do check the label on the package to see what your product is rated for.
And if you’re using a 100 day (very common) then it runs out in the middle of the summer.
This can be seen if your container starts to lag in growth or slow down in bloom production. The remedy is quite simple – start liquid feeding.
In either case, you really want to be adding liquid fertilizer to keep your plants producing flowers and fruit.
My Solution Is
When I had my nursery, we’d use a half dose of slow release with a half dose of liquid feeding on all the containers for the growing season. We’d give the customers who bought the really big baskets a small bag of slow release and tell them to put it on at the end of July to keep them growing right through to frost.