Yellow or Orange Balls in Soil: The Culprits [Solved]


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Noticing some colored balls (yellow or orange) in the pots of your home garden can be nerve-racking if you don’t know exactly what they are. However, these yellow balls in most cases are fertilizer prills.

The yellow or orange balls found in soil are slow-release Osmocote fertilizer balls used to supplement the soil’s nutrients over a period of time. These fertilizer balls disintegrate with increasing temperatures and can last a maximum of 5 months at 60oF or 15oC.

Although these balls are commonly added as a slow-release fertilizer in the soil they are mistaken for insect eggs most of the time.

After purchasing my first set of plants a couple of years ago, I found that most nurseries use this to keep their plants healthy for very long periods and so I have also adopted the same practice with my own plants. 

So don’t be alarmed about finding yellow balls in your soil. This article gives my personal account of discovering and using these “yellow balls” in soil (which turned out to be Osmocote balls) and the benefits that come with using them.

Yellow Balls In Potted plant Soil

Possible Reasons For Yellow Balls in Potting Soil:

I have found over the past years that most nurseries have used yellow osmocote balls in potting soil to help plants survive longer in their nursery pots. 

I have almost never come across yellow balls in potted plant soil being insect eggs. 

When insects lay eggs, the clutch of eggs will be close together so they can easily be protected by the host parent. 

I’ve seen in many cases over the years that insects such as ants will tend to harbor and nest at the bottom of the plant pot in order to get away from rain and wet conditions. 

Their eggs are much smaller and not even close to yellow as shown in the picture below
(This was from one of my potted plants that I kept outside).

Ant Nest from under Plant Pot

I have also found small frogs in my potted plants but not even them will lay eggs of such nature on soil. 

Frogs, snails and other crawling insects prefer clean surfaces with running water nearby as a source for food when the eggs hatch.

So to me it’s more of a myth to have insects, slugs and snails lay eggs on soil that can go dry very quickly under the right conditions, not to mention the hungry ants which will make an easy meal of the eggs.

However, with fertilizer balls, this is not the case. 

Let’s dive into the properties of these yellow fertilizer balls or prills and how they can benefit your plant.

Osmocote Fertilizer Balls:

Yellow balls in Soil
SummaryEach granule is coated with a unique resin that controls nutritional release so that plants get what they need when they need it. All-in-one granules contain all three major nutrients (NPK) that are vital to plant nutrition.
SizesAvailable in water-resistant bottles of 1.25 lb. and 3 lb. and in a re-sealable 10 lb. bag.
How to UseFor outdoor use, sprinkle evenly across areas to be fed and work into the top 1-3 inches of soil. When transplanting annuals from flats or when re-potting, mix into the soil and growing media at the bottom of the hole before planting. Water.
When to ApplyApply to outdoor plants every 4 months during the growing season. Can be applied to indoor plants, also every 4 months, year-round.
How Often to ApplyReapply every 4 months.
Where to useApply with confidence to potted plants, indoors or outdoors
Coverage AreaEstablished annuals and perennials: Sprinkle 3 tablespoons for every 2 x 2 ft area. Work into the top 1-3 inches of soil or mulch.
CautionsReentry may be achieved after you have watered in the product and the area has dried.
Fertilizer Analysis15-9-12 (ratio of N:P:K fertilizer)
Shelf LifeThe product will last for many years (+8) as long as the prills remain dry.

The data provided was sourced from Scotts Miracle-Gro which you can find here.

Note: There are different formulations of Osmocote fertilizer prills that are better suited for the plants they are being used on. These formulations will have different ratios of NPK fertilizer.

To fulfill the nutrients requirement of nursery plants, fertilizer prills are added to potting soil.

These fertilizer balls will slowly provide everything a plant needs for successful growth.

These balls are filled with fertilizer that turns into liquid and permeates outwards when subjected to moisture. More suitably these balls are known as “prills”.

Currently, there are different types of fertilizer prills accessible in the market but the most common type in use is made by the ScottsMiracle-Gro company. 

The formulation of Osmocote prills includes nutrients derived from the following nutrient elements:

  • Ammonium Nitrate 
  • Calcium Phosphate 
  • Ammonium Phosphates 
  • Calcium Fluoride 
  • Potassium Sulphate

According to the nutritional needs of plants, the amount of these chemical nutrients varies in slow-release fertilizer balls. 

If you are interested in a fertilizer that will help your plant stay healthy for a long time you can try this Osmocote fertilizer which can be found at a cheap price on Amazon.
You can find it by clicking here.

Osmocoat fertilizer

However, not all the yellow or orange balls in potting soil are fertilizer prills. 

In some very rare cases, these yellow or orange balls can be eggs of some insects that are feeding on your plants. 

Fertilizer Balls:

What are they Used for?

These colored fertilizer balls are added to potting soil only to stimulate the growth of your plants. The nutrients which are essential for the proper growth of plants will slowly release from these fertilizer balls. The nutrients include in them are: 

  • Nitrogen (N) 
  • Phosphorus (P)
  • Potassium (K)

Prills (fertilizers balls) won’t negatively affect or harm your plants until or unless you don’t add more than what is required. 

Remember, anything in excess, sooner or later, becomes poisonous. The fertilizer balls are not harmful to humans and pets as well only if they are not ingested in large amounts.

Characteristics of Fertilizer Balls:

  • The most apparent characteristics of fertilizer balls are their size and distinctive hard outer coating.
  • Fertilizer balls have spherical shapes that are uniformly spread across the surface of potting soil. 
  • Fertilizer balls are hard and dry.

Will They Go Away?

Yellow Fertilizer Balls in Soil

The picture above, clearly shows why some people may tend to think that the yellow balls in soil are eggs of insects and snails.

When initially placed in the soil the Osmocote balls are solid and yellow, but as they absorb water the fertilizer dissolves and passes through the permeable membrane into the soil. The balls then take a clear appearance resembling eggshells.

How much time will they take to completely degrade from the soil? What conditions will play a role in the degradation of these fertilizer balls?

From the data provided on the data label shown below. The hotter it gets, the fertilizer prills will tend to degrade faster.

60oF (15oC)70oF (15oC)80oF (15oC)90oF (15oC)
4 – 5 months3 – 4 months2 – 3 months1 – 2 months
Longevity of osmocote prills
This Graph represents the Data above

From my experience with having the yellow balls in potted plants both in sheltered and unsheltered areas, they do actually last longer in the plant pots that I have indoors than the ones that are subjected to rain and the elements.

The outer shell of fertilizer balls is hard and will take more time to vanish completely. 

The inner parts of the shell of these slow-release fertilizer balls contain liquid and have to pass through the outer shell. But it will take less time as compared to the outer shell. 

The release of the inner liquid is affected by the temperature and soil conditions of your plants. 

Higher temperatures will reduce the time taken by the inner part of the fertilizer ball to release. 

These fertilizer balls are known as slow-release fertilizers because releasing the nutrients from the balls is a slow process.  

Additionally, what I have seen after using these yellow balls over the years is that increased rainfall and watering also reduces the longevity of the prills in the soil.

Some Possible Culprits: (Maybe not)

Having potted plants for years, I personally have never seen insects lay eggs in potted plants although I myself have previously blamed the yellow balls I saw in my soil on laying insects.

Ants

What I do see often is ants in and around my potted plants with the occasional frog. 

Ants will tend to nest underneath the plant pot where they will find refuge from external rain and scorching sun. Their eggs are white and much smaller than the larger yellow Osmocoate prills 

Here I found a nesting colony of ants under one of my many plant pots which led me to start checking them a little more often than I usually do.

However, from my experience, I have found that ants do not cause any harm to potted plants nor the soil.

The occasional frog

Frog in plant pot with yellow balls

Frogs just like any other animal species like the refuge and safety there is in potted plants. And the one I have found shown in the picture below has become somewhat of a resident to this fiddle leaf fig plant. 

He seems very friendly and he has been there for two months. I assume he also likes the occasional ant he may find crawling around in the soil.

Frogs, however, will not lay eggs on potting soil. Frog eggs do not have a shell, so they need some kind of moisture to keep them from drying out until they hatch. 

Some frogs have come up with amazing ways to keep their eggs wet besides laying them directly in water.

Apart from frogs, dogs and cats also find refuge in potted plants and we have covered detailed articles on those and how to safely control this weird behavior.

What I also noticed in my soil was a few white fuzzy balls which was some type of fungus. I also know sometimes these white balls can also be perlite so I was not alarmed.

Insects’ Eggs

Although there are many accounts on web forums that plant owners have stated their experiences of yellow balls in soil. 

From my years of experience, I have never had slugs, snails, or worms lay eggs in my potted plants.

These creatures can definitely be found in garden soil in open areas where they are free to roam about unlike in potted plants where they can be confined.

The Takeaway

To conclude, yellow or orange balls are slow-release fertilizer prills from ScotsMiracle Gro.

The fertilizer balls are hard, spherical, and evenly distributed whereas insects’ eggs are more elongated, soft, and clustered in a single spot. 

This debunks the thought of having insect eggs in potting soil.

JayLea

JayLea has a passion for plants and has been gardening since 2015. He has valuable knowledge about gardening and houseplant care and can answer everyday practical questions that every plant owner has.

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