Fertilising guide
How to fertilise Rocky Mountain Juniper (Juniperus scopulorum)— schedule & NPK
Also called Rocky Mountain Juniper, Colorado Red Cedar.
More about rocky mountain juniper
About Rocky Mountain Juniper
Juniperus scopulorum · also called Rocky Mountain Juniper, Colorado Red Cedar · flowering
Rocky Mountain Juniper is a cold-hardy western conifer with soft blue-green scale foliage, valued as bonsai for its natural deadwood and reddish, shredding bark. An outdoor tree native to high, dry mountain country, it needs full sun, gritty fast-draining soil, and a proper winter chill. Overwatering and indoor keeping are its main downfalls.
Growth habit: Slow to moderate evergreen conifer, naturally upright to irregular and often picturesquely twisted; produces fine blue-green scale foliage and characterful weathered deadwood with age.
What fertiliser rocky mountain juniper actually wants — and why
Rocky Mountain Juniper is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.
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 rocky mountain juniper: 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 rocky mountain juniper, 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 rocky mountain juniper:
Apply a balanced bonsai fertiliser from spring to early autumn, leaning low-nitrogen to keep foliage compact; organic pellets or dilute liquid feed every 2-4 weeks works well. Pause feeding in winter. Treat that as every 2-4 weeks between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
The dormant-season rule matters more than the exact interval: skip feeding entirely when rocky mountain juniper 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 rocky mountain juniper
Half strength is the safe default for rocky mountain juniper — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
Feeding always goes onto already-damp soil, never dry roots — water rocky mountain juniper first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the rocky mountain juniper watering schedule.
Signs you are over-feeding rocky mountain juniper
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for rocky mountain juniper:
- Brown, crispy leaf tips and edges with no sign of underwatering.
- A white, crusty salt deposit on the soil surface or pot rim.
- Weak, pale, stretched new growth that flops.
- Lower leaves yellow and drop while the soil is correctly watered.
Signs you are under-feeding rocky mountain juniper
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full rocky mountain juniper care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of rocky mountain juniper with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Organic vs synthetic feeds for rocky mountain juniper
Organic options
A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.
Synthetic / liquid feeds
A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.
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 rocky mountain juniper — frequently asked questions
What fertiliser does rocky mountain juniper need?
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Rocky Mountain Juniper is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
How often should I feed rocky mountain juniper?
Apply a balanced bonsai fertiliser from spring to early autumn, leaning low-nitrogen to keep foliage compact; organic pellets or dilute liquid feed every 2-4 weeks works well. Pause feeding in winter. Apply a balanced bonsai fertiliser from spring to early autumn, leaning low-nitrogen to keep foliage compact; organic pellets or dilute liquid feed every 2-4 weeks works well. Pause feeding in winter. Treat that as every 2-4 weeks between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
What strength of feed for rocky mountain juniper?
Half strength is the safe default for rocky mountain juniper — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding rocky mountain juniper look like?
Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding rocky mountain juniper year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.
Should I flush the soil of rocky mountain juniper?
Flush the pot of rocky mountain juniper with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Keep reading
- Rocky Mountain Juniper care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water rocky mountain juniper — 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 peace lily
- How to fertilise bird of paradise
- How to fertilise hoya
- All 5561 fertilising guides in the Growli library