Container Soil Mix Library

Research-backed container soil mix recipes for 33 plants

Container soil chemistry is the difference between a tomato that flowers in July and one that quietly drops blossoms all season. Each recipe below is a starting point calibrated for one plant family — pepper, mint, blueberry, eggplant — built from peer-reviewed studies and university-extension fact sheets so you're not guessing at percentages.

Every recipe scales to your container size: the percentages stay fixed (because soil ratios don't care about pot size), but the per-container amendments (kelp meal, mycorrhizae, bone meal) and the total volume to mix scale linearly. Use the interactive calculator linked from each recipe page to compute the exact quantities for your pot.

Pick a plant below — recipes are grouped by category (vegetables, herbs, fruits, houseplants) and sorted alphabetically. The full ingredient list, pH and EC range, light requirements, and growing notes live on each recipe page.

Vegetables

Beet
Beta vulgaris

Dual-purpose root + greens crop that wants a loose, well-drained mix with adequate boron.

Container: 3-5 gal pot, 10 in+ deep
Broccoli
Brassica oleracea var. italica

Heavy-feeding cool-season brassica that needs even moisture and a fertile, slightly alkaline mix.

Container: 5 gal fabric, one head per pot
Bush bean
Phaseolus vulgaris

Nitrogen-fixing legume that fruits hard in a light, low-N mix with Rhizobium inoculant.

Container: 3-5 gal, several plants per pot
Cabbage
Brassica oleracea var. capitata

Cool-season brassica that forms tight heads in a fertile, moisture-retentive, near-neutral mix.

Container: 5 gal fabric, one head per pot
Carrot
Daucus carota subsp. sativus

Direct-seeded taproot crop that demands a loose, low-compost, stone-free sandy mix to grow straight.

Container: 5 gal deep pot (12 in+)
Cucumber
Cucumis sativus

Coco-coir-heavy container mix for cucumbers — highest CEC base per research, paired with pumice for chlorophyll and aeration.

Container: 5-7 gal + trellis
Eggplant
Solanum melongena

Heat-loving Solanaceae that fruits hard in a warm, evenly moist 5-gallon root zone.

Container: 5-7 gal fabric
Garlic
Allium sativum

Fall-planted, cold-vernalized bulb crop that wants free-draining, organic-rich soil at near-neutral pH.

Container: 5 gal wide pot, ~6 cloves
Kale
Brassica oleracea var. sabellica

Vigorous, frost-hardy brassica that wants loamy organic-rich soil and steady nitrogen.

Container: 3-5 gal fabric
Lettuce
Lactuca sativa

Shallow-rooted cool-season green that thrives in a moisture-retentive, vermicompost-rich mix.

Container: 2 gal / 30 cm wide planter
Onion
Allium cepa

Shallow-rooted heavy feeder early, then tapering N — wants loose, organic, evenly moist soil.

Container: 5 gal wide pot, multiple bulbs
Pepper
Capsicum spp.

Research-backed container soil mix for peppers (Capsicum spp.) — vermicompost-forward with charged biochar for CEC and BER-preventing calcium amendments.

Container: 5-gallon fabric or plastic
Pepper (Biochar-Blend simplified)
Capsicum spp.

Simplified pepper mix using Organic Mechanics Biochar Blend (or similar all-in-one) in place of separate biochar + compost + zeolite + minerals + meal amendments.

Container: 5-gallon fabric or plastic
Potato
Solanum tuberosum

Acidic, low-N container mix for potatoes — the yield driver is the hilling technique, not the soil composition.

Container: 15+ gallon fabric grow bag (5 gal soil per plant)
Radish
Raphanus sativus

Loose, lean, deeply-loosened mix so roots size up smooth and round without forking.

Container: 1-5 gal (≥6" depth)
Spinach
Spinacia oleracea

Cool-season nitrogen-hungry green that prefers a near-neutral, well-amended container mix.

Container: 2 gal wide planter
Squash
Cucurbita pepo / moschata

Container soil mix for bush and vining squash — pumice-heavy for water efficiency, vermicompost for slow N.

Container: 10-15 gal bush / 20+ gal vining
Tomato
Solanum lycopersicum

Heavy-feeder tomato soil mix optimized for indeterminate and determinate varieties in containers.

Container: 10-15 gal indeterminate / 5-7 gal determinate
Tomato (Biochar-Blend simplified)
Solanum lycopersicum

Simplified tomato mix using Organic Mechanics Biochar Blend (or similar all-in-one) in place of separate biochar + compost + zeolite + minerals + meal amendments.

Container: 10-15 gal indeterminate / 5-7 gal determinate

Herbs

Basil
Ocimum basilicum

Fertile, evenly-moist mix for big leafy harvests from a heat-loving annual.

Container: 1-5 gal
Chives
Allium schoenoprasum

Well-drained, fertility-balanced mix for a hardy perennial allium.

Container: 1-3 gal
Cilantro
Coriandrum sativum

Light, fast-draining mix for cilantro — bolts in heat, hates wet feet, resents transplanting (direct-sow only).

Container: 6-8" deep minimum (taproot); direct-sow into final pot
Dill
Anethum graveolens

Deep, slightly acidic, organically-rich mix for a tall taproot annual.

Container: 2-5 gal (deep)
Mint
Mentha spp.

Moisture-loving herb mix for mint — high water retention, steady fertility, and always solo (mint chokes neighbors).

Container: 1-3 gal — always its own pot
Oregano
Origanum vulgare

Well-drained, slightly alkaline mix for a vigorous spreading Mediterranean herb.

Container: 1-3 gal
Parsley
Petroselinum crispum

Deep-rooted biennial herb that wants a moist, fertile, free-draining mix.

Container: 1-5 gal (deep)
Rosemary
Salvia rosmarinus

Lean, gritty, sharply-drained Mediterranean mix — root rot is the #1 killer.

Container: 2-7 gal (terracotta preferred)
Sage
Salvia officinalis

Sandy-loamy, sharply-drained mix for a drought-tolerant Mediterranean shrub-herb.

Container: 2-5 gal
Thyme
Thymus vulgaris

Gritty, low-fertility mix mimicking the dry, gravelly slopes thyme is native to.

Container: 1-3 gal

Fruits

Blueberry
Vaccinium corymbosum

Strictly acidic ericaceous mix dominated by pine bark fines and peat — non-negotiable pH 4.5-5.2.

Container: 5-25 gal (start 5, repot to 16-25)
Roselle
Hibiscus sabdariffa

Container soil mix for roselle (Hibiscus sabdariffa) — sandy-loam-mimicking, biochar-enhanced for salinity tolerance.

Container: 7-10 gal
Strawberry
Fragaria × ananassa

Free-draining, organically-rich, slightly acidic mix for sweet container berries.

Container: 2-10 gal (or strawberry pots)

Houseplants

Peperomia
Peperomia spp.

Drainage-first houseplant mix for Peperomia — semi-succulent epiphyte, hates wet feet, light feeder.

Container: 4-6 in (likes being snug/slightly rootbound)

How these recipes are built

Each recipe starts with a base structure (a quality bagged potting mix or a hand-mixed substrate) and adds three categories of ingredients: components (coco coir, perlite, pumice, vermicompost, biochar) blended by percentage of volume; amendments (kelp meal, mycorrhizae, bone meal, gypsum) dosed per gallon of container; and a list of citations (university extension fact sheets, peer-reviewed papers) backing the choices.

We chose ingredient ratios using a small number of consistent rules: heavy feeders (tomato, pepper, eggplant, brassicas) get more compost or vermicompost; Mediterranean herbs (rosemary, thyme, oregano, sage) get more pumice/sand for drainage and lean fertility; root crops (carrot, beet, radish) get a low-compost loose mix to grow straight; blueberries get an ericaceous (acidic) mix dominated by pine bark fines and sphagnum peat. The full reasoning is on each recipe page.

For the in-app interactive version that saves mixes to your plot plants and tracks applied dates, see the garden.gg dashboard.