Can I use garden soil to make potting soil?

Clemson Cooperative Extension says garden soils contain too many bacteria and are generally not recommended for plants grown in containers — if you insist on using garden soil, it must be pasteurized by spreading it on a cookie tray and baking until the coolest spot reaches 180°F for 30 minutes, then amended with bark, peat, perlite, or sand. The University of Georgia Extension is more permissive: its container-gardening guide says a mixture of 50 percent soil and 50 percent organic matter works well. The safe default is a soilless mix; the two sources disagree on garden soil, so report both honestly rather than endorsing raw garden soil.

What is the simplest homemade potting soil recipe?

The LSU AgCenter's basic potting mix: 2 parts peat moss or coconut coir (pre-moistened), 2 parts compost or composted manure, 1 part perlite, one-quarter to one-half part vermiculite, plus 1 tablespoon of garden lime for each gallon of peat moss. It covers the four jobs every mix must do — structure, drainage, water retention, and nutrients — in one recipe.

How much lime do I add to a homemade potting mix?

Both Penn State Extension and the University of Georgia Extension converge on about 5 pounds of dolomitic lime per cubic yard of potting mixture — Penn State lists 5 pounds per cubic yard for its standard soilless mix, and UGA recommends 4 to 5 pounds per cubic yard. At home scale, the LSU AgCenter says 1 tablespoon of garden lime for each gallon of peat moss, and Cornell University's foliage-plant mix calls for 8 tablespoons of ground dolomitic lime per bushel.

Should I use peat moss or coconut coir in my potting mix?

Clemson Cooperative Extension calls coconut coir a popular, lower-cost, more sustainable alternative to peat moss — but warns to rinse it thoroughly before use to avoid salinity problems. Peat moss is the traditional base because it is stable and slow to decompose, per the LSU AgCenter. Either works as the water-holding base of a recipe; just never use fine muck-type peat, which the University of Georgia says decreases aeration.

Why did my seedlings die in my homemade mix?

The most common culprit is unfinished or salty compost. Penn State Extension warns that mixes made with compost can be high in salts, which inhibits germination, and that unfinished compost releases volatile organic acids that harm seedlings — finished compost smells sweet, while sour or putrid smells mean the pile needs to re-heat before the compost goes into a mix. Poor drainage is the other killer: the University of Georgia notes that container soils drain poorly because of shallow depth and reduced capillary pull, so stressed roots get invaded by root-rotting fungi.

How do I fertilize plants in homemade potting soil?

If the mix was amended when you built it, the University of Georgia Extension says no fertilizer is needed for the first 2 to 3 weeks, then feed with a liquid fertilizer every 2 to 3 weeks. Clemson Cooperative Extension's plant mix feeds with a water-soluble 20-20-20 fertilizer with trace elements at every seventh watering. For bulk batches, UGA recommends 5 pounds of a complete fertilizer per cubic yard of mix, such as 5-10-15 or 6-12-12, in a premium grade with major and minor elements.

How to make potting soil

By Muzamil Ali · Last updated November 1, 2026

Learn how to make potting soil with three university-extension recipes. Exact ratios, lime and fertilizer rates, plus the ingredients to avoid.

Learning how to make potting soil yourself is one of the highest-value skills in container gardening: a bag of premium mix is mostly peat, perlite, and compost that you can blend for a fraction of the price, and you get to control exactly what goes into it. The catch is that a potting mix is not just "dirt in a bucket" — every good mix has to do four jobs at once: hold the plant upright, drain freely, hold enough water and air for roots, and supply nutrients. Get the balance wrong and you get waterlogged roots or seedlings that stall out. The three recipes below all come from US university extension services — Penn State, Clemson, LSU AgCenter, Cornell, and the University of Georgia — with the lime and fertilizer rates that make them work, so you know how to make potting soil that performs like the bagged stuff.

What every potting mix has to do

Before the recipes, it helps to know why the ingredients are there. The University of Georgia Extension explains that soilless mixtures are typically vermiculite plus peat moss plus perlite or ground pine bark, and that the last two are in the mix to improve drainage and aeration. The four jobs:

Structure and stability — peat moss or coconut coir is the primary ingredient because it is stable and slow to decompose (LSU AgCenter). It holds the plant and gives roots something to grip.
Drainage and aeration — perlite and coarse bark open up pore space. UGA warns that container mixes drain poorly because shallow depth reduces capillary pull, and poorly drained mixes let root-rotting fungi invade stressed roots. Perlite is the classic fix.
Water and nutrient retention — vermiculite lightens the mix so water and oxygen move through it, and it adds calcium and magnesium while increasing water retention (LSU AgCenter).
Nutrients — compost, plus a measured dose of lime and fertilizer. Compost is an amendment, not a fertilizer on its own, so every recipe below includes lime and a fertilizer source.

Knowing how to make potting soil starts with respecting that balance: a mix that is all compost holds too much water and can be too salty for seedlings; a mix that is all peat and perlite has nothing to feed the plant.

Recipe 1: the simple basic mix (LSU AgCenter)

If you only memorize one recipe for how to make potting soil, make it this one from the LSU AgCenter's container-media series. It is the easiest to scale to any container:

2 parts peat moss or coconut coir, pre-moistened
2 parts compost or composted manure
1 part perlite
1/4 to 1/2 part vermiculite
1 tablespoon of garden lime for each gallon of peat moss

Mix everything thoroughly. "Parts" can be any container — a bucket, a scoop, a wheelbarrow — as long as you use the same one for every ingredient. The peat or coir supplies the structure, the compost supplies organic matter and some nutrients, the perlite handles drainage, and the vermiculite holds water between waterings. The tablespoon of lime per gallon of peat corrects the acidity that peat brings; Penn State's standard soilless mix uses 5 pounds of dolomitic lime per cubic yard on the same principle. This recipe is a good general-purpose answer to how to make potting soil for vegetables, herbs, and flowers alike.

One caution from the same LSU publication: some home recipes floating around the internet add a part of garden soil. Do not treat that as a recommendation — Clemson Cooperative Extension says garden soils contain too many bacteria and are generally not recommended for containers, and any garden soil you use must be pasteurized first (more on that below).

Recipe 2: the balanced organic mix (Penn State Extension)

Penn State Extension's organic potting mix trades a little simplicity for a richer, longer-lasting blend — a good pick when you are learning how to make potting soil for heavy feeders like tomatoes and peppers:

1 part sphagnum peat moss
1 part peat humus
1 part compost
1 part sharp (builder's) sand
Per 80 quarts of mix: 1 cup greensand, 1 cup colloidal phosphate, 1-1/2 to 2 cups crabmeal or blood meal, and 1/2 cup lime

Screen the compost through 1/4-inch hardware cloth before blending so large chunks do not create air pockets. Penn State's nutrition targets for a premium mix explain what you are aiming for: pH 5.5 to 6.5, soluble salts 1.5 to 3 mmhos/cm, nitrate-N 75 to 150 mg/L, P 5 to 20 mg/L, and K 150 to 300 mg/L, all measured on a saturated paste. You do not need a lab to mix the recipe — the amendment rates per 80 quarts are already calibrated — but the targets tell you why the lime and mineral meals are not optional.

Penn State also gives a leaner soilless recipe if you want to understand the anatomy of how to make potting soil from scratch: 1 part compost to 1 part vermiculite to 1 part peat moss, with 0.6 ounces of blood meal, 0.4 ounces of clay phosphate, and 0.4 ounces of greensand per gallon of mix. And its seed-starting mix — 50 to 75 percent sphagnum peat, 25 to 50 percent vermiculite, 5 pounds of ground dolomitic lime per cubic yard, and blood meal, rock phosphate, and greensand at 5 to 10 pounds per cubic yard — is worth knowing because seedlings are far more sensitive to salts than established plants.

Recipe 3: the Cornell foliage-plant mix (for houseplants)

Cornell University's foliage-plant mix, published by Clemson Cooperative Extension, is formulated by volume per bushel and is the classic answer to how to make potting soil for indoor plants:

1/2 bushel sphagnum peat moss
1/4 bushel vermiculite No. 2
1/4 bushel perlite (medium fine)
8 tablespoons ground dolomitic lime
2 tablespoons superphosphate (20 percent, powdered)
3 tablespoons 10-10-10 fertilizer
1 tablespoon iron sulfate
1 tablespoon potassium nitrate

A bushel is 1.25 cubic feet, so this is roughly a 10-gallon batch. The iron sulfate and potassium nitrate are the details that separate a houseplant mix from an outdoor one: indoor plants live in the same mix for a year or more, so the recipe front-loads micronutrients and a complete fertilizer. Clemson notes that high-quality mixes usually contain slow-release fertilizer that feeds for a few months but run low on trace elements — this recipe corrects that.

Clemson also publishes three simpler by-volume foliage recipes for when you want to learn how to make potting soil without a scale: 2 parts peat to 1 part perlite to 1 part coarse sand; 2 parts peat to 1 part coarse sand; or 1 part peat to 1 part coarse sand to 1 part pine bark. And its own Clemson Plant Mix — 2 parts pine bark (soil-conditioning grade) to 1 part peat to 1 part sand, adjusted to about pH 6.0 with dolomitic limestone — is fed with water-soluble 20-20-20 with trace elements at every seventh watering.

The lime and fertilizer rates that make the recipes work

The ingredient ratios get the physics right; the lime and fertilizer get the chemistry right. Both Penn State and the University of Georgia converge on the same lime rate: about 5 pounds of dolomitic lime per cubic yard of potting mixture (Penn State lists 5 pounds for its standard soilless mix; UGA recommends 4 to 5 pounds). The lime supplies calcium and magnesium while adjusting pH. At home scale, LSU's rule of thumb — 1 tablespoon of garden lime per gallon of peat moss — lands in the same neighborhood, which is one less number to memorize when you are learning how to make potting soil.

For fertilizer in bulk batches, UGA recommends 5 pounds per cubic yard of mix (a cubic yard is 27 cubic feet), using a complete fertilizer such as 5-10-15, 5-10-10, or 6-12-12 — or 3-3/4 ounces per bushel (1.25 cubic feet). Choose a premium grade with major and minor elements, and do not overdo it: UGA warns that over-fertilization damages roots. Two timing rules complete the picture. First, if the mix was amended when you built it, UGA says no fertilizer is needed for the first 2 to 3 weeks, then feed with liquid fertilizer every 2 to 3 weeks. Second, for seed-starting mixes, the University of Georgia's own recipe — 4 quarts shredded sphagnum peat moss, 4 quarts fine vermiculite, 1 tablespoon superphosphate, 2 tablespoons ground limestone — must be mixed, wetted completely, drained, and then left alone for 5 to 6 days before planting, so the lime has time to react with the peat. LSU adds that seedlings need supplemental nutrients about 2 weeks after emergence, which is why a seed mix can start leaner than a potting mix. Our seed-starting guide walks through the timing side of that.

Ingredients and habits to avoid

Knowing how to make potting soil is half knowing what to leave out:

Raw garden soil. Clemson is blunt: garden soils contain too many bacteria and are generally not recommended for containers. If you insist on using it, pasteurize it — spread it on a cookie tray and bake until the coolest spot reaches 180°F for 30 minutes — then amend with bark, peat, perlite, or sand. Note the honest disagreement: UGA's container guide says 50 percent soil plus 50 percent organic matter "works well." The safe default, and this article's recommendation, is the soilless route.
Unfinished or salty compost. Penn State warns that compost-based mixes can be high in salts, which inhibits germination, and that unfinished compost releases volatile organic acids that harm seedlings. Finished compost smells sweet; sour or putrid smells mean the pile needs to re-heat before that compost goes anywhere near a pot. Our compost troubleshooting guide covers how to get a pile truly finished.
Fine muck-type peat. UGA specifically warns against fine, muck-type peat because it decreases aeration. Use coarse sphagnum peat moss.
Layering instead of blending. UGA's practical advice: blend the mix thoroughly, because layering ingredients interferes with root growth. Pre-wet peat and bark — both are hard to wet and need repeated soaking — then mix.
Fertilizing a fresh mix immediately. If you amended the mix at blending time, UGA says skip fertilizer for the first 2 to 3 weeks. Over-fertilized roots are damaged roots.

Peat moss vs coconut coir: which base?

The base ingredient is the one choice where you can reasonably swap. Peat moss is the traditional base: the LSU AgCenter calls it the primary ingredient because it is stable and slow to decompose. Coconut coir is the modern alternative: Clemson calls it a popular, lower-cost, more sustainable option for gardeners learning how to make potting soil — with one firm warning to rinse it thoroughly before use to avoid salinity problems. Our perlite vs vermiculite guide covers the other half of the drainage equation if you are still deciding on ingredients.

How to make potting soil: a worked example

Here is how to make potting soil for a real weekend project. Say you need to fill four 5-gallon containers — roughly 20 gallons of mix, or about 2.7 cubic feet. Use Recipe 1 (the LSU basic mix) and a 1-gallon scoop as your "part": 2 scoops of pre-moistened peat moss, 2 scoops of finished compost (screened through 1/4-inch mesh, sweet-smelling, per Penn State's maturity test), 1 scoop of perlite, and a heaping half-scoop of vermiculite — that is 5.5 scoops, about 5.5 gallons per round, so four rounds fills your containers. Add 1 tablespoon of garden lime per gallon of peat as you go (2 tablespoons per round). Blend each round thoroughly in a wheelbarrow — no layering — and dampen the peat first, since dry peat resists wetting. Before you mix, use our potting soil calculator to confirm the volume, and if you are converting between quarts, cubic feet, and cubic yards, our soil volume converter keeps the math straight (remember: a cubic yard is 27 cubic feet). Fill the containers, water until it drains from the bottom, and you are done — hold the fertilizer for 2 to 3 weeks, then start a liquid feed every 2 to 3 weeks per UGA's schedule.

That is how to make potting soil the extension way: a real recipe with real rates, blended thoroughly, with the compost finished and the lime measured. The bagged mix at the garden center is convenient, but it is not magic — it is peat, perlite, compost, lime, and fertilizer, and now you know the proportions.

Sources

Every figure in this guide to how to make potting soil comes from one of these pages, verified on the page itself:

Penn State Extension — Potting Media and Plant Propagation (premium mix targets pH 5.5–6.5 and soluble salts 1.5–3 mmhos/cm; standard soilless seed mix 50–75% peat and 25–50% vermiculite with 5 lbs dolomitic lime per cubic yard; soilless potting mix 1:1:1 compost, vermiculite, peat with 0.6 oz blood meal, 0.4 oz clay phosphate, 0.4 oz greensand per gallon; organic mix 1:1:1:1 peat, peat humus, compost, sharp sand with 1 cup greensand, 1 cup colloidal phosphate, 1-1/2–2 cups crabmeal or blood meal, 1/2 cup lime per 80 quarts; compost salt and unfinished-compost warnings; NOP compost standard 131–170°F)
Clemson Cooperative Extension (HGIC) — Indoor Plants – Soil Mixes (garden soil not recommended for containers; pasteurization at 180°F for 30 minutes; coir as a sustainable peat alternative that must be rinsed; four foliage-plant recipes; Cornell foliage mix per bushel with lime, superphosphate, 10-10-10, iron sulfate, and potassium nitrate; Clemson Plant Mix 2:1:1 bark, peat, sand at pH ~6.0 fed with 20-20-20 every seventh watering)
LSU AgCenter — Growing Media for Containers, Part 4: Media Recipes (basic potting mix 2:2:1 peat or coir, compost, perlite with 1/4–1/2 part vermiculite and 1 Tbsp garden lime per gallon of peat; University of Georgia seed-starting mix with 5–6 day rest; University of Florida seed-starting and foliage mixes; UC Mix 1; peat as the stable primary ingredient; vermiculite's water, calcium, and magnesium roles; seedlings needing nutrients ~2 weeks after emergence)
University of Georgia Extension — Gardening in Containers, Circular 787 (soilless mixture definition; container drainage physics and root-rotting fungi; 50/50 soil and organic matter DIY option; ground pine bark at 1/4–1/2 in as best amendment; fine muck peat warning; 2:2:1 soil, peat, perlite ratio; 4–5 lbs dolomitic lime and 5 lbs fertilizer per cubic yard; 3-3/4 oz per bushel; cubic yard = 27 cu ft and bushel = 1.25 cu ft; pre-wetting, thorough blending, no layering; no fertilizer for the first 2–3 weeks, then liquid feed every 2–3 weeks)