Journal/Care Basics · 6 min read
When and How to Fertilize Houseplants
The complete guide to fertilizing houseplants: which NPK ratio, how often, and the signs your plant is hungry (or overfed).
Quick answer
Feed most houseplants a balanced liquid fertilizer (roughly 10-10-10 or 3-1-2) at half strength every 2–4 weeks in spring and summer, and stop feeding from October to February. Never fertilize dry soil, sick plants, or a plant you just repotted.
Fertilizer doesn't 'feed' a plant the way food feeds you — it replenishes the mineral nutrients that potting soil runs out of after a few months. Get the frequency and dilution right and it's the single biggest lever for growth.
What NPK actually means
The three numbers on any fertilizer bottle are the percentages of Nitrogen (N), Phosphorus (P), and Potassium (K). N drives leaf growth, P drives roots and flowers, K drives overall vigour. For foliage houseplants, look for balanced ratios (10-10-10) or slightly higher nitrogen (3-1-2 or 24-8-16).
How often?
Feeding frequency by season
| Season | Frequency | Dilution |
|---|---|---|
| Spring (Mar–May) | Every 2 weeks | Half strength |
| Summer (Jun–Aug) | Every 2 weeks | Half strength |
| Autumn (Sep–Oct) | Every 4 weeks | Quarter strength |
| Winter (Nov–Feb) | None | — |
Types of fertilizer
- Liquid concentrates — most control, easiest to dilute, great for beginners.
- Slow-release pellets — dropped on the soil, feed for 3–6 months. Good if you travel.
- Organic (worm castings, fish emulsion) — gentle, hard to overdose, but smell.
Signs a plant is hungry
Pale, uniformly yellow-green new growth, tiny new leaves, or a plant that hasn't grown at all in three months during summer. Old, tired soil is usually the cause.
Signs a plant is overfed
White crust on the soil surface or pot rim, brown crispy leaf tips, or sudden leaf drop. Flush the pot with plain water three times to leach out salts and skip your next two feeds.
When not to fertilize
- For six weeks after repotting — fresh soil already has enough nutrients.
- When the plant is stressed, sick, or dropping leaves.
- When the soil is bone-dry — feed a moist plant to protect the roots.
PlantMe times feeding reminders to the actual species and season, not a generic monthly ping.
Frequently asked questions
Can I fertilize in winter?
Usually no. Most houseplants slow down and don't use the nutrients — extra salts build up and burn the roots. The exceptions are winter bloomers like Christmas cactus and citrus.
Is coffee ground good fertilizer?
In small amounts as a soil amendment, yes. As a top-dressing on houseplant soil, no — it forms a crust that repels water and can go mouldy. Compost it first.
What NPK for flowering plants?
A phosphorus-heavy ratio like 10-30-20 encourages blooms. Switch from a balanced fertilizer to a bloom formula about six weeks before you want flowers.
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