Liquid Fertiliser for Fruit Sizing: Formulas That Increase Fruit Size

Why fruit size matters

Liquid fertiliser for fruit sizing is a critical production tool both for competitiveness in the market and for harvest income. Grade directly determines the sale price; larger fruit always fetches more.

The factors that determine fruit size:

• The number of cell divisions (up to 3–4 weeks after fruit set)
• Cell expansion capacity (a long period lasting until ripening)
• Efficiency of carbohydrate and water transport
• Hormone balance · especially cytokinin and gibberellin

Which elements should a sizing fertiliser contain?

Potassium (K) · the energy carrier

Potassium regulates the transport of photosynthetic products from the leaves to the fruit through the phloem. When potassium is insufficient, sugar and carbohydrate do not accumulate in the fruit; it stays small and bland. Potassium demand is at its highest during ripening.

Zinc (Zn) · triggers the growth hormone

Zinc is the key to auxin (growth hormone) synthesis. Auxin drives cell elongation; without enough of it, cells may divide but cannot grow. Where zinc is deficient, fruit sets but does not size up.

Boron (B) · eases sugar transport

Boron directly affects the movement of sugar produced in the leaves to the fruit through the phloem. When boron is insufficient the fruit receives no energy and cell division slows.

A fruit sizing programme with Casablanca

The zinc, trace elements and natural biostimulants in Casablanca create synergy at every phase of the sizing process:

• 7–10 days after fruit set: first zinc application · support for cell division
• Fruit at pea size: potassium + zinc combination
• During rapid growth: a foliar application every 10 days
• Before ripening (4–5 weeks out): intensive potassium + boron

The difference between a "swelling agent" and a sizing programme

Products known as fruit swelling agents usually contain gibberellin (GA3). Gibberellins force cell elongation and enlarge the fruit, but they lower sugar content and can spoil quality. A natural zinc + potassium + boron combination increases size while preserving the Brix value.

Recommendations by species

Tomato: Casablanca plus a potassium fertiliser every 10 days from fruit set to just before harvest.
Pepper: repeat the fruit set application after every flowering wave.
Peach / plum: intensify in May–June, when fruit growth rate is highest.
Grape: for berry sizing, apply from veraison through the berry growth period.

Frequently asked questions

When should a fruit sizing fertiliser be used?

It should start immediately after fruit set and continue until 3–4 weeks before harvest. The most critical period is the mid-development phase, when the fruit grows fastest.

Is there a natural fruit sizing product?

Yes · a zinc + potassium + boron combination supports fruit sizing without synthetic growth regulators. Casablanca supplies these elements from naturally sourced raw materials.

Does a sizing fertiliser lower Brix?

Fertilisers based on natural elements preserve or raise the Brix value. Chemical enlargers containing gibberellin can lower it.

What rate should be applied for fruit sizing?

150–200 ml of Casablanca per 100 L of water. If a potassium fertiliser is applied alongside, check mixing compatibility and run a small trial first.