Soil & potting mix
Best soil for wavy hair grass (Deschampsia flexuosa)
Also called wavy hair grass, crinkled hair grass.
More about wavy hair grass
About wavy hair grass
Deschampsia flexuosa · also called wavy hair grass, crinkled hair grass · flowering
Wavy hair grass is a delicate, wiry cool-season perennial grass of acid heathlands, moorlands, and open woodlands in Europe and North America. Its slender, hair-fine leaves form low, dark-green tussocks from which airy, wavy-stemmed panicles of tiny, glistening spikelets rise in early summer. Ideal for acid soils, heath gardens, and naturalised moorland settings with striking translucent flower clouds.
Preferred mix: Acid, free-draining, nutrient-poor sandy or peaty soil
Watch for — Alkaline soil failure: Yellowing, poor growth, and death result from neutral or alkaline soils; test pH before planting and correct to below 6.5 with sulphur chips or plant in ericaceous compost.
Why wavy hair grass needs this mix
wavy hair grass is a true acid-lover — it physically cannot take up iron above about pH 5.5, so an ericaceous mix is not optional, it is survival.
- wavy hair grass has evolved on acidic, peaty ground and depends on soil fungi that only function in acid conditions — raise the pH and it starves even in "rich" soil.
- In a too-alkaline mix iron and manganese lock up chemically, so the youngest leaves yellow between green veins (lime-induced chlorosis) and the plant fades out.
- Its fine, shallow roots also want an open, free-draining structure, not a heavy clay or claggy compost.
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 wavy hair grass struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:
- Ordinary multipurpose or garden compost is far too alkaline for wavy hair grass — expect classic yellowing, weak growth and a slow decline over a season or two.
- Hard tap water slowly pushes the pH up too, undoing a good mix; rainwater is strongly preferred for watering.
- Lime, mushroom compost or wood ash anywhere near this plant is actively harmful.
Planting wavy hair grass in standard compost or limey garden soil. Without an acidic (ericaceous) medium it will yellow and fail no matter how well you water and feed it.
pH — does it matter for wavy hair grass?
This is the whole game: wavy hair grass needs pH 4.5-5.5. Test it, use ericaceous compost (and an ericaceous feed), and water with rainwater where you can to keep the pH from creeping up.
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
Bagged ericaceous compost is the correct, easy base for wavy hair grass; just open it up with bark and grit per the ratio above. Do not try to acidify ordinary compost by guesswork — it rarely holds.
Drainage and the pot
Containers are often easier than open ground because you control the pH completely. Use a pot with good drainage and an ericaceous mix; never let it sit waterlogged.
Top up or refresh the ericaceous mix yearly and test the pH each spring — it naturally drifts upward over time, especially if watered with tap water. When the time comes, our repotting guide for wavy hair grass covers the timing and technique step by step.
wavy hair grass soil — frequently asked questions
What is the best soil mix for wavy hair grass?
3 parts ericaceous (acidic) compost : 1 part composted pine bark or pine needles : 1 part perlite or coarse grit. wavy hair grass has evolved on acidic, peaty ground and depends on soil fungi that only function in acid conditions — raise the pH and it starves even in "rich" soil.
Can I use normal potting soil for wavy hair grass?
Ordinary multipurpose or garden compost is far too alkaline for wavy hair grass — expect classic yellowing, weak growth and a slow decline over a season or two. Bagged ericaceous compost is the correct, easy base for wavy hair grass; just open it up with bark and grit per the ratio above. Do not try to acidify ordinary compost by guesswork — it rarely holds.
Does wavy hair grass need a special pH?
This is the whole game: wavy hair grass needs pH 4.5-5.5. Test it, use ericaceous compost (and an ericaceous feed), and water with rainwater where you can to keep the pH from creeping up.
Should I buy a bagged mix or make my own for wavy hair grass?
Bagged ericaceous compost is the correct, easy base for wavy hair grass; just open it up with bark and grit per the ratio above. Do not try to acidify ordinary compost by guesswork — it rarely holds.
How often should I refresh the soil for wavy hair grass?
Top up or refresh the ericaceous mix yearly and test the pH each spring — it naturally drifts upward over time, especially if watered with tap water. Containers are often easier than open ground because you control the pH completely. Use a pot with good drainage and an ericaceous mix; never let it sit waterlogged.
Keep reading
- wavy hair grass care — the full brief (light, water, humidity, problems, pet safety)
- How often to water wavy hair grass — the schedule the mix feeds into
- Repotting wavy hair grass — when and how to refresh the mix
- Soil pH guide — test it and adjust it safely
- Root rot — how the wrong soil starts it, and how to save the plant
- Underwatered plant — signs and how to rehydrate it
- Should I water my plant? The simple check first
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- Best soil for aeschynanthus radicans 'curly q'
- Best soil for tuberous begonia
- All 6887 soil and potting-mix guides in the Growli library