Peat — What It Is, Acidic or Neutral, and Where It Belongs in a Tbilisi Garden

Peat is in every agro shop in Tbilisi, yet most bags are bought for the wrong job. Tbilisi soil is heavy clay with free lime and a pH above 7.5, and in that soil peat does some things brilliantly and others not at all. Here is where it earns its place, where it is money thrown away, and how to use it properly.

What peat actually is

Peat is partly decomposed bog moss, mostly sphagnum, built up over thousands of years in waterlogged ground. Nearly all the bagged peat sold in Georgia is imported from the Baltic states. Three properties define it:

• It holds water — several times its own dry weight, and releases it slowly.
• It is light and airy — far lighter than garden soil, which is why it dominates potting mixes.
• It has almost no nutrients — peat is a structure material, not a fertiliser. Anything planted in it has to be fed.

And one property that matters more here than anywhere: raw sphagnum peat is strongly acidic, pH roughly 3.5–4.5.

Acidic or neutralised — read the bag

• Acidic ("high-moor") peat. Light brown, fibrous, pH 3.5–4.5, nothing added. This is the one for acid-loving plants.
• Neutralised peat. The same material with lime blended in to bring it to pH 5.5–6.5, often with a starter dose of fertiliser. This is the general-purpose seed and potting material. The pH is printed on the bag. If it is not, assume you do not know what you are buying.

Where peat earns its place in Tbilisi

Acid-loving plants. This is the main reason to buy the acidic grade. Blueberries need a pH of about 4.5–5.5 and simply will not grow in Tbilisi ground; the only reliable way is a large pot or a dug-out bed filled with acidic peat and pine bark. Azalea, rhododendron, camellia and heather (Erica) are in the same group. Hydrangea tolerates our soil but turns pink in it — peat in the planting pit pushes the colour towards blue for a while, and our hydrangea guide explains why it never stays that way. Magnolia appreciates the same treatment in the planting pit.

Seed starting and cuttings. Neutralised peat with perlite or vermiculite is the classic sowing mix: light, moist, free of weed seed. Proportions are in our vermiculite and perlite guide.

Pots and balcony boxes. Garden soil in a container compacts into a brick. A peat-based mix with a quarter of perlite stays open for a whole season.

Lightening heavy planting pits. One part peat to two parts excavated clay in the backfill makes a shrub's first year noticeably easier. Compost does the same job and feeds as well.

Where it is money thrown away

• As a bulk amendment for a clay yard. An 80-litre bag covers one square metre to about 8 cm. To change a 100 m² bed you would need a truckload, and in soil with free lime the acidity is buffered away within a season or two anyway. Structure in Tbilisi clay comes from compost and gypsum, not peat — the full programme is in our clay and alkaline soil guide.
• Under a lawn. In heavy clay a peat layer becomes a sponge holding water above the subsoil, and roots rot in it. Screened topsoil and grading decide a lawn, which is why we treat it as part of lawn installation, not as an additive.
• As mulch. Peat dries into a water-repellent crust, blows away, and sheds the very rain you wanted in the soil. Bark mulch or compost does that job.
• Mediterranean and drought-adapted plants. Olive, lavender, rosemary, juniper, most succulents. These die of wet feet, not thirst — peat in their root zone is the opposite of what they need, as our olive tree guide explains.

How to use it correctly

1. Wet it first. Dry peat repels water. Tip it into a tub, add water, and work it through until a squeezed handful releases a few drops. Planting into dry peat is the most common way it fails.
2. Never plant into pure peat. Mix it: one part peat to one part garden soil or compost for beds; for pots add a quarter of perlite.
3. Expect the pH to drift back up. Tbilisi tap water carries lime, so a pot of blueberries in acidic peat creeps back towards neutral over a season. Water acid-lovers with rainwater where you can, and re-acidify with elemental sulphur at the rate a soil test gives.
4. Feed what grows in it. Peat supplies nothing: a slow-release fertiliser at planting and liquid feed through the season are not optional.

What it costs

At our shop prices at the time of writing, 80 litres of peat is 28 GEL. That bag fills roughly four 20-litre pots, or improves the backfill of two medium shrub pits mixed at one part in three. A whole bed of blueberries means several bags per plant and a lined, raised bed — at that point it is worth talking it through first.

Before you buy

The deciding question is what your soil measures, not what the bag promises. A soil analysis gives the pH and lime content, and that decides whether peat is a fix or a gesture. If you are planting acid-loving shrubs this autumn, Dr. VERDE's seasonal agrotechnical works cover soil preparation, pit mixing and planting, and a yard-care plan keeps the feeding and watering on schedule afterwards.