Fertilising guide
How to fertilise Old Man Saltbush (Atriplex nummularia)— schedule & NPK
Also called Old man saltbush, Giant saltbush, Australian saltbush, Bluish saltbush.
More about old man saltbush
About Old Man Saltbush
Atriplex nummularia · also called Old man saltbush, Giant saltbush · edible
Atriplex nummularia is a large, fast-growing, evergreen shrub native to the arid and semi-arid interior of Australia, where it is one of the most ecologically and agriculturally significant native plants. Its silvery, salty leaves are used as a distinctive seasoning in modern Australian cuisine and provide highly nutritious browse for sheep and cattle in dryland farming. The single most important care fact is that this plant must have full sun and free-draining soil — it tolerates extreme salinity, alkalinity, and drought but is sensitive to waterlogging and high humidity. It is not listed as toxic by the ASPCA, but oxalate content means it should be classified as mildly-toxic for pets.
Growth habit: Large, sprawling to upright multi-branched evergreen shrub with oval, silvery-grey, mealy leaves; produces small inconspicuous greenish flowers in summer followed by clusters of fruiting bracts.
What fertiliser old man saltbush actually wants — and why
Old Man Saltbush 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 old man saltbush: 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 old man saltbush, 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 old man saltbush:
Rarely needs feeding; in highly fertile soil, excessive growth can lead to reduced leaf quality and increased pest susceptibility — grow lean for the best compact form. 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 old man saltbush 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 old man saltbush
Follow the crop-feed label rate for old man saltbush — 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 old man saltbush first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the old man saltbush watering schedule.
Signs you are over-feeding old man saltbush
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for old man saltbush:
- 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 old man saltbush
- 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 old man saltbush 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 old man saltbush 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 old man saltbush
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 old man saltbush — frequently asked questions
What fertiliser does old man saltbush 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. Old Man Saltbush 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 old man saltbush?
Rarely needs feeding; in highly fertile soil, excessive growth can lead to reduced leaf quality and increased pest susceptibility — grow lean for the best compact form. Rarely needs feeding; in highly fertile soil, excessive growth can lead to reduced leaf quality and increased pest susceptibility — grow lean for the best compact form. 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 old man saltbush?
Follow the crop-feed label rate for old man saltbush — 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 old man saltbush 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 old man saltbush 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 old man saltbush?
In containers, fertiliser salts build up fast — water old man saltbush 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
- Old Man Saltbush care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water old man saltbush — 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 grape 'niagara'
- How to fertilise grape 'marquette'
- How to fertilise grape 'frontenac'
- All 10153 fertilising guides in the Growli library