Growli
Let's go

Fertilising guide

How to fertilise Begonia (Begonia × hortensis)— schedule & NPK

Also called wax begonia, bedding begonia, fibrous begonia.

About Begonia

Begonia × hortensis · also called wax begonia, bedding begonia · flowering

Bedding begonias are tender perennials grown as compact annuals with waxy leaves and small white, pink, or red flowers. Tolerate sun and part shade. Mildly toxic to pets through soluble calcium oxalates in tubers and stems.

Begonia is a tropical and subtropical forest-understory genus; tuberous types trace to montane South America and southern Africa. Garden begonias split into three habits: fibrous-rooted wax (Semperflorens), tuberous, and rhizomatous foliage types.

A balanced dilute feed through active growth suits foliage and bloom; tuberous types ease off feeding as foliage yellows and the tuber goes dormant for cool, dry winter storage.

Growth habit: Compact bushy annual

Watch for — Few flowers: Too much shade or under-feeding.

Sources: extension.umn.edu, extension.umn.edu, rhs.org.uk

What fertiliser begonia actually wants — and why

Begonia 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 begonia: 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 begonia, 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 begonia:

Half-strength balanced feed every 3-4 weeks during flowering. Treat that as every 3-4 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 begonia 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 begonia

Half strength is the safe default for begonia — 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 begonia first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the begonia watering schedule.

Signs you are over-feeding begonia

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for begonia:

Signs you are under-feeding begonia

If the symptoms point at watering, light or roots rather than nutrition, the full begonia care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Flush the pot of begonia 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 begonia

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 begonia — frequently asked questions

What fertiliser does begonia 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. Begonia 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 begonia?

Half-strength balanced feed every 3-4 weeks during flowering. Half-strength balanced feed every 3-4 weeks during flowering. Treat that as every 3-4 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 begonia?

Half strength is the safe default for begonia — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.

What does over-feeding begonia 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 begonia 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 begonia?

Flush the pot of begonia 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