Fertilising guide
How to fertilise Redwood Sorrel (Oxalis oregana)— schedule & NPK
Also called Redwood Sorrel, Oregon Oxalis.
More about redwood sorrel
About Redwood Sorrel
Oxalis oregana · also called Redwood Sorrel, Oregon Oxalis · edible
A vigorous Pacific coast ground-cover perennial carpeting the floor of redwood and mixed conifer forests with large, clover-like trifoliate leaves and white or pink flowers spring through autumn. Leaves are edible in small amounts with a lemony tang. An outstanding shade ground cover for moist western gardens; spreads freely by rhizome.
Growth habit: Creeping, mat-forming, evergreen perennial spreading via branching rhizomes
What fertiliser redwood sorrel actually wants — and why
Redwood Sorrel feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.
Balanced (even N-P-K) at planting for roots and frame, then switch to a high-potassium ("high-potash") tomato-style feed once the first flowers open — potassium is what sizes and ripens fruit, not nitrogen.
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 redwood sorrel: 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 redwood sorrel, 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 redwood sorrel:
Minimal fertilization needed in humus-rich soils. Top-dress with leaf mold or compost in autumn. In lean garden soils, a light application of balanced slow-release fertilizer in spring supports lush foliage. So: a balanced feed or compost at planting, then a high-potash liquid every 1-2 weeks from first flower through harvest across the main season (spring through early autumn).
The dormant-season rule matters more than the exact interval: skip feeding entirely when redwood sorrel 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 redwood sorrel
Follow the crop-feed label rate for redwood sorrel — these are calibrated for hungry vegetables. Consistency through fruiting matters more than strength; erratic feeding causes problems like blossom-end rot.
Feeding always goes onto already-damp soil, never dry roots — water redwood sorrel first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the redwood sorrel watering schedule.
Signs you are over-feeding redwood sorrel
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for redwood sorrel:
- Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen).
- Lush foliage hiding the crop; soft growth prone to pests and disease.
- Salt crust on the soil and scorched leaf edges in containers.
Signs you are under-feeding redwood sorrel
- Pale, yellowing lower leaves and stunted growth.
- Small fruit, poor set, and a quickly exhausted plant.
- Blossom-end rot and weak cropping from erratic or insufficient feeding.
If the symptoms point at watering, light or roots rather than nutrition, the full redwood sorrel care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
In containers, fertiliser salts build up fast — water redwood sorrel thoroughly so excess drains from the base each time, and flush pots with plain water every few weeks to prevent a damaging salt build-up.
Organic vs synthetic feeds for redwood sorrel
Organic options
Garden compost or well-rotted manure dug in before planting, plus a liquid comfrey or seaweed feed once fruiting starts. UK: comfrey feed or organic Tomorite; US: Espoma Tomato-tone or Neptune's Harvest. Builds soil and feeds in one.
Synthetic / liquid feeds
A balanced feed at planting then a high-potash tomato feed in fruiting — UK: Growmore at planting then Tomorite (Levington) or Phostrogen; US: a balanced 10-10-10 then Miracle-Gro Tomato or a bloom booster.
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 redwood sorrel — frequently asked questions
What fertiliser does redwood sorrel need?
Balanced (even N-P-K) at planting for roots and frame, then switch to a high-potassium ("high-potash") tomato-style feed once the first flowers open — potassium is what sizes and ripens fruit, not nitrogen. Redwood Sorrel feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.
How often should I feed redwood sorrel?
Minimal fertilization needed in humus-rich soils. Top-dress with leaf mold or compost in autumn. In lean garden soils, a light application of balanced slow-release fertilizer in spring supports lush foliage. Minimal fertilization needed in humus-rich soils. Top-dress with leaf mold or compost in autumn. In lean garden soils, a light application of balanced slow-release fertilizer in spring supports lush foliage. So: a balanced feed or compost at planting, then a high-potash liquid every 1-2 weeks from first flower through harvest across the main season (spring through early autumn).
What strength of feed for redwood sorrel?
Follow the crop-feed label rate for redwood sorrel — these are calibrated for hungry vegetables. Consistency through fruiting matters more than strength; erratic feeding causes problems like blossom-end rot.
What does over-feeding redwood sorrel look like?
Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen). Lush foliage hiding the crop; soft growth prone to pests and disease. Salt crust on the soil and scorched leaf edges in containers. Staying on a high-nitrogen feed once redwood sorrel starts flowering is the classic error — you get a huge leafy plant and a disappointing crop. Switch to high-potash the moment flowers appear.
Should I flush the soil of redwood sorrel?
In containers, fertiliser salts build up fast — water redwood sorrel thoroughly so excess drains from the base each time, and flush pots with plain water every few weeks to prevent a damaging salt build-up.
Keep reading
- Redwood Sorrel care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water redwood sorrel — 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 chardonnay grape
- How to fertilise cabernet sauvignon grape
- How to fertilise muscat grape
- All 8452 fertilising guides in the Growli library