Soil & potting mix
Best soil for King of Hearts Brunnera (Brunnera macrophylla 'King of Hearts')
Also called King of Hearts Siberian bugloss.
More about king of hearts brunnera
About King of Hearts Brunnera
Brunnera macrophylla 'King of Hearts' · also called King of Hearts Siberian bugloss · flowering
King of Hearts is a robust Siberian bugloss with large, heavily frosted silver leaves veined and edged in green, giving strong all-season shine in shade. Sprays of small blue forget-me-not flowers appear in spring. This clump-forming woodland perennial is more sun- and heat-tolerant than green forms but still needs cool, evenly moist soil.
Preferred mix: Humus-rich, moisture-retentive, well-drained loam (pH 6.0-7.5)
Watch for — Leaf scorch: Sun and drought brown the silvered leaf edges; plant in cool shade with shelter and keep the soil reliably moist.
Why king of hearts brunnera needs this mix
King of Hearts Brunnera hates drying out, so it wants a mix that stays evenly moist — but it still needs perlite so "moist" never tips into "waterlogged".
- King of Hearts Brunnera comes from damp, shaded forest floors and has fine roots that scorch and brown the moment the rootball dries — the mix has to hold a steady reserve.
- Coir and compost give that reserve, while perlite keeps enough air that the constantly-moist mix does not turn anaerobic.
- Even moisture also keeps its thin leaves from crisping at the edges, which is this plant’s most visible stress signal.
For the full picture on what makes up a good mix, see our guide to the main types of soil and potting media — it explains why each ingredient above behaves the way it does.
What goes wrong with the wrong mix
The wrong soil is one of the most common reasons king of hearts brunnera struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:
- A free-draining, gritty mix dries too fast for king of hearts brunnera — you get crispy brown edges and frond or leaf drop within days of one missed watering.
- A pure, airless peat mix swings the other way: it holds water but suffocates the fine roots and rots the crown.
- Letting the mix dry to the point it shrinks from the pot is very hard to re-wet evenly and stresses the plant badly.
Using a sharp, fast-draining "houseplant" or cactus-leaning mix that lets king of hearts brunnera dry out. It needs a moisture-retentive but still airy blend.
pH — does it matter for king of hearts brunnera?
King of Hearts Brunnera prefers a slightly acidic mix (around pH 5.5-6.5); a peat-free compost-and-coir blend sits there naturally, so routine pH testing is unnecessary.
If you want to check or adjust it, the soil pH guide walks through testing and the safe ways to nudge a mix more acidic or more alkaline.
DIY mix vs a bagged one
A good peat-free houseplant compost works for king of hearts brunnera straight from the bag if you mix in some perlite for air. The DIY ratio above gives a more reliable moisture-to-air balance.
Drainage and the pot
Use a pot with a drainage hole but a less-porous material (plastic or glazed) so it does not dry too fast. Bottom-watering keeps the mix evenly moist without sogging the crown.
Peat-free mixes slump and compact as they hold moisture, so refresh king of hearts brunnera's mix every 12-18 months to keep air in the rootball even if the pot size is unchanged. When the time comes, our repotting guide for king of hearts brunnera covers the timing and technique step by step.
King of Hearts Brunnera soil — frequently asked questions
What is the best soil mix for king of hearts brunnera?
3 parts peat-free houseplant compost : 1 part coco coir : 1 part perlite. King of Hearts Brunnera comes from damp, shaded forest floors and has fine roots that scorch and brown the moment the rootball dries — the mix has to hold a steady reserve.
Can I use normal potting soil for king of hearts brunnera?
A free-draining, gritty mix dries too fast for king of hearts brunnera — you get crispy brown edges and frond or leaf drop within days of one missed watering. A good peat-free houseplant compost works for king of hearts brunnera straight from the bag if you mix in some perlite for air. The DIY ratio above gives a more reliable moisture-to-air balance.
Does king of hearts brunnera need a special pH?
King of Hearts Brunnera prefers a slightly acidic mix (around pH 5.5-6.5); a peat-free compost-and-coir blend sits there naturally, so routine pH testing is unnecessary.
Should I buy a bagged mix or make my own for king of hearts brunnera?
A good peat-free houseplant compost works for king of hearts brunnera straight from the bag if you mix in some perlite for air. The DIY ratio above gives a more reliable moisture-to-air balance.
How often should I refresh the soil for king of hearts brunnera?
Peat-free mixes slump and compact as they hold moisture, so refresh king of hearts brunnera's mix every 12-18 months to keep air in the rootball even if the pot size is unchanged. Use a pot with a drainage hole but a less-porous material (plastic or glazed) so it does not dry too fast. Bottom-watering keeps the mix evenly moist without sogging the crown.
Keep reading
- King of Hearts Brunnera care — the full brief (light, water, humidity, problems, pet safety)
- How often to water king of hearts brunnera — the schedule the mix feeds into
- Repotting king of hearts brunnera — when and how to refresh the mix
- Soil pH guide — test it and adjust it safely
- Underwatered plant — signs and how to rehydrate it
- Why is my plant wilting? Wet vs dry diagnosis
- Should I water my plant? The simple check first
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