Fertilising guide
How to fertilise Rounded Sweetgum (Liquidambar styraciflua 'Rotundiloba')— schedule & NPK
Also called Rounded Sweetgum, Fruitless Sweetgum, Rotundiloba Sweetgum.
More about rounded sweetgum
About Rounded Sweetgum
Liquidambar styraciflua 'Rotundiloba' · also called Rounded Sweetgum, Fruitless Sweetgum · flowering
A fruitless cultivar of American sweetgum prized for its rounded, non-lobed leaves and spectacular fall color ranging from burgundy to orange-gold. Unlike the straight species, 'Rotundiloba' produces no spiny seed balls, making it an ideal street or lawn tree. It thrives in full sun with consistent moisture and well-drained, slightly acidic soil.
Growth habit: Upright, broadly pyramidal deciduous tree with a dense canopy; somewhat oval with age.
Watch for — Chlorosis (yellowing leaves): Caused by high soil pH preventing iron uptake. Test soil pH and amend with sulphur or acidifying fertiliser if above 6.5. Chelated iron foliar spray can provide quick relief.
What fertiliser rounded sweetgum actually wants — and why
Rounded Sweetgum 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 rounded sweetgum: 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 rounded sweetgum, 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 rounded sweetgum:
Apply a balanced slow-release fertiliser (e.g. 10-10-10) in early spring before bud break. Young trees benefit from annual feeding; established specimens typically need little supplemental fertiliser if growing in good soil. 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 rounded sweetgum 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 rounded sweetgum
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for rounded sweetgum. The variable that actually matters is pH, not concentration.
Feeding always goes onto already-damp soil, never dry roots — water rounded sweetgum first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the rounded sweetgum watering schedule.
Signs you are over-feeding rounded sweetgum
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for rounded sweetgum:
- 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 rounded sweetgum
- 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 rounded sweetgum care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush rounded sweetgum 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 rounded sweetgum
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 rounded sweetgum — frequently asked questions
What fertiliser does rounded sweetgum 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. Rounded Sweetgum 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 rounded sweetgum?
Apply a balanced slow-release fertiliser (e.g. 10-10-10) in early spring before bud break. Young trees benefit from annual feeding; established specimens typically need little supplemental fertiliser if growing in good soil. Apply a balanced slow-release fertiliser (e.g. 10-10-10) in early spring before bud break. Young trees benefit from annual feeding; established specimens typically need little supplemental fertiliser if growing in good soil. 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 rounded sweetgum?
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for rounded sweetgum. The variable that actually matters is pH, not concentration.
What does over-feeding rounded sweetgum 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 rounded sweetgum 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 rounded sweetgum?
Flush rounded sweetgum 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
- Rounded Sweetgum care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water rounded sweetgum — 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 ranunculus aquatilis
- How to fertilise nymphoides peltata
- How to fertilise sparganium erectum
- All 8452 fertilising guides in the Growli library