Fertilising guide
How to fertilise Foxglove (Digitalis purpurea)— schedule & NPK
Also called Foxglove, Common Foxglove, Lady's Glove, Fairy Fingers.
More about foxglove
About Foxglove
Digitalis purpurea · also called Foxglove, Common Foxglove · flowering
Digitalis purpurea is a tall biennial or short-lived perennial native to western and central Europe, including the UK, where it is a quintessential woodland-edge and cottage-garden plant. In its first year it forms a large flat rosette of velvety leaves; in its second it throws up a commanding spike of tubular, spotted flowers beloved by bumblebees. The most important care fact is to site it in partial shade with moisture-retentive, humus-rich soil, and to allow self-seeding for a continuous display. Every part of this plant is highly toxic to pets and humans.
Growth habit: Biennial (sometimes short-lived perennial): flat first-year rosette followed by a tall, erect, often branched second-year flower spike; self-seeds prolifically to maintain colony presence.
Watch for — Aphid infestation on flower spike: Foxglove aphids (Acyrthosiphon cyparissiae) and other species colonise the developing flower spikes in late spring, causing stunted or distorted flowers; knock off with a strong water jet or introduce ladybird larvae.
What fertiliser foxglove actually wants — and why
Foxglove 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 foxglove: 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 foxglove, 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 foxglove:
Mulch with leafmould or garden compost in autumn; a single application of a balanced slow-release fertiliser in spring of the second year supports stem development without producing soft tissue susceptible to powdery mildew. Treat that as sparingly through the growing season 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 foxglove 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 foxglove
Half strength is the safe default for foxglove — 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 foxglove first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the foxglove watering schedule.
Signs you are over-feeding foxglove
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for foxglove:
- 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 foxglove
- 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 foxglove care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of foxglove 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 foxglove
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 foxglove — frequently asked questions
What fertiliser does foxglove 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. Foxglove 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 foxglove?
Mulch with leafmould or garden compost in autumn; a single application of a balanced slow-release fertiliser in spring of the second year supports stem development without producing soft tissue susceptible to powdery mildew. Mulch with leafmould or garden compost in autumn; a single application of a balanced slow-release fertiliser in spring of the second year supports stem development without producing soft tissue susceptible to powdery mildew. Treat that as sparingly through the growing season 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 foxglove?
Half strength is the safe default for foxglove — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding foxglove 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 foxglove 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 foxglove?
Flush the pot of foxglove 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
- Foxglove care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water foxglove — 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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- All 10153 fertilising guides in the Growli library