Fertilising guide
How to fertilise Cas Guava (Eugenia victoriana)— schedule & NPK
Also called Cas Guava, Costa Rican Guava, Cas.
More about cas guava
About Cas Guava
Eugenia victoriana · also called Cas Guava, Costa Rican Guava · tropical
Cas Guava is a slow-growing Central American tropical shrub prized for its tart, aromatic fruits used in juices and preserves. It thrives in humid, warm climates with full sun and well-drained, slightly acidic soil. Suitable for large containers in temperate climates; it needs frost protection and consistent moisture during fruit development.
Growth habit: Upright, multi-stemmed evergreen shrub or small tree
What fertiliser cas guava actually wants — and why
Cas Guava is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for cas guava: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed cas guava, and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For cas guava:
Apply a balanced slow-release fertiliser (e.g. 10-10-10) in early spring and midsummer. During fruit development supplement with a potassium-rich liquid feed every 3–4 weeks. Avoid high-nitrogen feeds once flowering begins as they promote vegetative growth at the expense of fruiting. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
The dormant-season rule matters more than the exact interval: skip feeding entirely when cas guava is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for cas guava
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for cas guava. The variable that actually matters is pH, not concentration.
Feeding always goes onto already-damp soil, never dry roots — water cas guava first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the cas guava watering schedule.
Signs you are over-feeding cas guava
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for cas guava:
- Brown, scorched leaf margins from too strong or too frequent a dose.
- White salt crust on the soil surface.
- Soft, lush growth that fruits or flowers poorly.
Signs you are under-feeding cas guava
- Yellowing leaves with green veins (iron chlorosis from high pH).
- Weak growth, poor cropping and an overall pale, stressed look.
- Stunted new shoots in spring despite adequate water and light.
If the symptoms point at watering, light or roots rather than nutrition, the full cas guava care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush cas guava with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Organic vs synthetic feeds for cas guava
Organic options
Composted pine bark, pine-needle mulch, used coffee grounds and an organic ericaceous feed gently maintain acidity. UK: Vitax or Westland Ericaceous; US: Espoma Holly-tone or Dr. Earth Acid Lovers. Slow, soil-improving, hard to overdo.
Synthetic / liquid feeds
A liquid or granular ericaceous feed — UK: Miracle-Gro Ericaceous, Vitax or Westland; US: Miracle-Gro Acid-Loving Plant Food or Espoma Holly-tone. Pair with rainwater and an acidic mulch for it to work.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising cas guava — frequently asked questions
What fertiliser does cas guava need?
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves. Cas Guava is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
How often should I feed cas guava?
Apply a balanced slow-release fertiliser (e.g. 10-10-10) in early spring and midsummer. During fruit development supplement with a potassium-rich liquid feed every 3–4 weeks. Avoid high-nitrogen feeds once flowering begins as they promote vegetative growth at the expense of fruiting. Apply a balanced slow-release fertiliser (e.g. 10-10-10) in early spring and midsummer. During fruit development supplement with a potassium-rich liquid feed every 3–4 weeks. Avoid high-nitrogen feeds once flowering begins as they promote vegetative growth at the expense of fruiting. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
What strength of feed for cas guava?
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for cas guava. The variable that actually matters is pH, not concentration.
What does over-feeding cas guava look like?
Brown, scorched leaf margins from too strong or too frequent a dose. White salt crust on the soil surface. Soft, lush growth that fruits or flowers poorly. Feeding cas guava an ordinary fertiliser, or growing it in hard tap water / limey soil, is the defining mistake — it triggers lime-induced chlorosis (yellow leaves, green veins) no amount of feeding fixes until the pH comes down.
Should I flush the soil of cas guava?
Flush cas guava with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Keep reading
- Cas Guava care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water cas guava — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise anubias barteri var. nana
- How to fertilise anubias barteri var. nana 'petite'
- How to fertilise anubias congensis
- All 8452 fertilising guides in the Growli library