Fertilising guide
How to fertilise Pelargonium x domesticum 'Lavender Grand Slam' (Pelargonium x domesticum 'Lavender Grand Slam')— schedule & NPK
Also called Lavender Grand Slam pelargonium, Regal pelargonium Lavender Grand Slam.
More about pelargonium x domesticum 'lavender grand slam'
About Pelargonium x domesticum 'Lavender Grand Slam'
Pelargonium x domesticum 'Lavender Grand Slam' · also called Lavender Grand Slam pelargonium, Regal pelargonium Lavender Grand Slam · flowering
'Lavender Grand Slam' is a free-flowering regal pelargonium with large lavender-mauve ruffled blooms feathered and blotched in deeper purple, carried in generous trusses. More floriferous than many regals, it puts on a long spring-to-summer show on upright, bushy plants with crinkled, slightly sticky leaves. It likes cool nights and bright filtered light, grown as a tender perennial under glass or on a patio.
Growth habit: Upright, bushy evergreen perennial with stiff, serrated, slightly sticky leaves and abundant ruffled flower trusses.
What fertiliser pelargonium x domesticum 'lavender grand slam' actually wants — and why
Pelargonium x domesticum 'Lavender Grand Slam' flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.
Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency.
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 pelargonium x domesticum 'lavender grand slam': 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 pelargonium x domesticum 'lavender grand slam', 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 pelargonium x domesticum 'lavender grand slam':
Feed every 1-2 weeks with a balanced liquid feed in spring, switching to high-potash as buds form; stop feeding after flowering and over winter. In practice: no routine feeding at all for pelargonium x domesticum 'lavender grand slam' — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.
The dormant-season rule matters more than the exact interval: skip feeding entirely when pelargonium x domesticum 'lavender grand slam' 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 pelargonium x domesticum 'lavender grand slam'
None is the correct answer for pelargonium x domesticum 'lavender grand slam'. The flower-versus-foliage trade-off is the whole point: hold back and you get the display.
Feeding always goes onto already-damp soil, never dry roots — water pelargonium x domesticum 'lavender grand slam' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the pelargonium x domesticum 'lavender grand slam' watering schedule.
Signs you are over-feeding pelargonium x domesticum 'lavender grand slam'
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for pelargonium x domesticum 'lavender grand slam':
- Abundant leafy growth and very few flowers (the classic over-rich symptom).
- Soft, floppy stems and a sprawling, leafy habit.
- Scorched edges and salt crust if it has been fed in a container.
Signs you are under-feeding pelargonium x domesticum 'lavender grand slam'
- Effectively never an issue — these plants flower on poverty.
- Only on genuinely dead soil: weak, thin growth and few blooms.
- A short-lived plant in completely spent container compost.
If the symptoms point at watering, light or roots rather than nutrition, the full pelargonium x domesticum 'lavender grand slam' care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
If pelargonium x domesticum 'lavender grand slam' has accidentally been fed and is all leaf, a plain-water flush plus a move to leaner soil resets it; otherwise no flushing is needed because you are not feeding it.
Organic vs synthetic feeds for pelargonium x domesticum 'lavender grand slam'
Organic options
A thin compost mulch for soil structure is the absolute most; mostly, give it nothing. UK/US: leave it lean — no manure, no liquid feed. Poor soil is the active ingredient here.
Synthetic / liquid feeds
None. Synthetic feeds, particularly anything with appreciable nitrogen, directly suppress flowering in pelargonium x domesticum 'lavender grand slam'.
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 pelargonium x domesticum 'lavender grand slam' — frequently asked questions
What fertiliser does pelargonium x domesticum 'lavender grand slam' need?
Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency. Pelargonium x domesticum 'Lavender Grand Slam' flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.
How often should I feed pelargonium x domesticum 'lavender grand slam'?
Feed every 1-2 weeks with a balanced liquid feed in spring, switching to high-potash as buds form; stop feeding after flowering and over winter. Feed every 1-2 weeks with a balanced liquid feed in spring, switching to high-potash as buds form; stop feeding after flowering and over winter. In practice: no routine feeding at all for pelargonium x domesticum 'lavender grand slam' — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.
What strength of feed for pelargonium x domesticum 'lavender grand slam'?
None is the correct answer for pelargonium x domesticum 'lavender grand slam'. The flower-versus-foliage trade-off is the whole point: hold back and you get the display.
What does over-feeding pelargonium x domesticum 'lavender grand slam' look like?
Abundant leafy growth and very few flowers (the classic over-rich symptom). Soft, floppy stems and a sprawling, leafy habit. Scorched edges and salt crust if it has been fed in a container. Feeding pelargonium x domesticum 'lavender grand slam' at all — especially "to help it flower" — is the defining mistake. Rich soil gives you a big green plant and almost no blooms; restraint is what produces the flowers.
Should I flush the soil of pelargonium x domesticum 'lavender grand slam'?
If pelargonium x domesticum 'lavender grand slam' has accidentally been fed and is all leaf, a plain-water flush plus a move to leaner soil resets it; otherwise no flushing is needed because you are not feeding it.
Keep reading
- Pelargonium x domesticum 'Lavender Grand Slam' care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water pelargonium x domesticum 'lavender grand slam' — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
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