Mix-Your-Own Seed-Starting Blend (Simple Recipe That Actually Works) 🌱🪣

Donna Scarborough

24d • Garden Gear & DIY Hacks

(𝐵𝑒𝑐𝑎𝑢𝑠𝑒 𝑠𝑒𝑒𝑑𝑙𝑖𝑛𝑔𝑠 𝑑𝑜𝑛’𝑡 𝑛𝑒𝑒𝑑 “𝑓𝑎𝑛𝑐𝑦”—𝑡ℎ𝑒𝑦 𝑛𝑒𝑒𝑑 𝑙𝑖𝑔ℎ𝑡, 𝑓𝑙𝑢𝑓𝑓𝑦, 𝑎𝑛𝑑 𝑟𝑒𝑙𝑖𝑎𝑏𝑙𝑒.)

If you’ve ever started seeds and ended up with:

* slow sprouting

* moldy soil

* seedlings that fall over

* mix that stays soggy forever

…it’s often not your fault. A lot of bagged mixes are inconsistent, or they hold too much water indoors.

The good news? You can make an easy seed-starting blend at home that’s:

✅ light and airy

✅ drains well (but still holds moisture)

✅ great for indoor winter seed starting

✅ adjustable based on your conditions

𝐖𝐡𝐚𝐭 𝐚 𝐠𝐨𝐨𝐝 𝐬𝐞𝐞𝐝-𝐬𝐭𝐚𝐫𝐭𝐢𝐧𝐠 𝐦𝐢𝐱 𝐌𝐔𝐒𝐓 𝐝𝐨

Seedlings need a mix that:

* holds moisture evenly (not puddles)

* has air pockets (roots need oxygen)

* drains well (prevents damping-off)

* is fine-textured so tiny seeds aren’t blocked by chunky bits

𝐓𝐡𝐞 𝐒𝐢𝐦𝐩𝐥𝐞 𝐑𝐞𝐜𝐢𝐩𝐞 (𝐁𝐞𝐠𝐢𝐧𝐧𝐞𝐫-𝐅𝐫𝐢𝐞𝐧𝐝𝐥𝐲)

𝐁𝐚𝐬𝐢𝐜 𝐒𝐞𝐞𝐝-𝐒𝐭𝐚𝐫𝐭𝐢𝐧𝐠 𝐁𝐥𝐞𝐧𝐝 (𝟑 𝐩𝐚𝐫𝐭𝐬 𝐭𝐨𝐭𝐚𝐥)

* 2 parts coco coir (or peat moss)

* 1 part perlite (for drainage + air)

That’s it. Truly.

𝐖𝐡𝐲 𝐢𝐭 𝐰𝐨𝐫𝐤𝐬: coco/peat holds moisture evenly, perlite keeps it from compacting and staying soggy.

𝐎𝐩𝐭𝐢𝐨𝐧𝐚𝐥 𝐮𝐩𝐠𝐫𝐚𝐝𝐞𝐬 (𝐩𝐢𝐜𝐤 𝐛𝐚𝐬𝐞𝐝 𝐨𝐧 𝐲𝐨𝐮𝐫 𝐧𝐞𝐞𝐝𝐬)

𝐈𝐟 𝐲𝐨𝐮𝐫 𝐡𝐨𝐦𝐞 𝐢𝐬 𝐝𝐫𝐲 𝐚𝐧𝐝 𝐲𝐨𝐮’𝐫𝐞 𝐟𝐨𝐫𝐠𝐞𝐭𝐭𝐢𝐧𝐠 𝐭𝐨 𝐰𝐚𝐭𝐞𝐫:

Add ½ part vermiculite (it holds moisture a little longer)

𝐈𝐟 𝐲𝐨𝐮𝐫 𝐬𝐞𝐞𝐝𝐥𝐢𝐧𝐠𝐬 𝐤𝐞𝐞𝐩 𝐝𝐚𝐦𝐩𝐢𝐧𝐠 𝐨𝐟𝐟 𝐨𝐫 𝐲𝐨𝐮𝐫 𝐦𝐢𝐱 𝐬𝐭𝐚𝐲𝐬 𝐰𝐞𝐭:

Use a little extra perlite (make it closer to 1:1)

𝐈𝐟 𝐲𝐨𝐮 𝐰𝐚𝐧𝐭 𝐚 𝐭𝐢𝐧𝐲 𝐧𝐮𝐭𝐫𝐢𝐞𝐧𝐭 𝐛𝐨𝐨𝐬𝐭 (𝐧𝐨𝐭 𝐫𝐞𝐪𝐮𝐢𝐫𝐞𝐝 𝐟𝐨𝐫 𝐠𝐞𝐫𝐦𝐢𝐧𝐚𝐭𝐢𝐨𝐧):

Add ½ part worm castings (or sifted compost)

Just a little—seedlings don’t need a rich buffet at the start.

𝐈𝐦𝐩𝐨𝐫𝐭𝐚𝐧𝐭: If you add compost/castings, keep it light. Too rich can encourage fungus and gnats indoors.

𝐇𝐨𝐰 𝐭𝐨 𝐦𝐢𝐱 𝐢𝐭 (𝐭𝐡𝐞 𝐞𝐚𝐬𝐲 𝐰𝐚𝐲)

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𝟏. Use any “scoop” (cup, yogurt container, small bucket)

𝟐. Mix dry ingredients in a tub/bin

𝟑. Add water slowly and stir until it feels like:

* damp like a wrung-out sponge

* not dripping wet

* no dry pockets

𝐏𝐫𝐨 𝐭𝐢𝐩: Pre-moistening is the secret to even watering later.

“𝐁𝐮𝐭 𝐝𝐨 𝐈 𝐧𝐞𝐞𝐝 𝐬𝐭𝐞𝐫𝐢𝐥𝐞 𝐦𝐢𝐱?”

For most home seed starting, you don’t need to overthink “sterile.”

What matters more is:

* clean trays

* not overwatering

* good airflow

* using a mix that drains well

That said, if you’ve had damping-off before, keeping things extra clean (and avoiding compost in the mix) is a smart move.

𝐂𝐨𝐦𝐦𝐨𝐧 𝐦𝐢𝐬𝐭𝐚𝐤𝐞𝐬 (𝐚𝐧𝐝 𝐪𝐮𝐢𝐜𝐤 𝐟𝐢𝐱𝐞𝐬)

❌ 𝐓𝐨𝐨 𝐰𝐞𝐭

𝐅𝐢𝐱: add more perlite and bottom-water instead of top-watering.

❌ 𝐓𝐨𝐨 𝐝𝐫𝐲/𝐡𝐲𝐝𝐫𝐨𝐩𝐡𝐨𝐛𝐢𝐜

(especially with peat/coir if not pre-moistened)

𝐅𝐢𝐱: pre-wet it thoroughly in a bin before filling trays.

❌ 𝐅𝐮𝐧𝐠𝐮𝐬 𝐠𝐧𝐚𝐭𝐬

𝐅𝐢𝐱: avoid compost-heavy mixes indoors, let the surface dry slightly, and use bottom watering.

❌ 𝐌𝐢𝐱 𝐢𝐬 𝐜𝐡𝐮𝐧𝐤𝐲

𝐅𝐢𝐱: sift out big pieces. Tiny seeds prefer fine texture.

𝐖𝐡𝐞𝐧 𝐭𝐨 𝐬𝐭𝐚𝐫𝐭 𝐟𝐞𝐫𝐭𝐢𝐥𝐢𝐳𝐢𝐧𝐠

Seeds don’t need fertilizer to sprout.

Once seedlings have their first set of true leaves (not the first baby leaves), then you can start a very mild feeding if needed.

𝐐𝐮𝐞𝐬𝐭𝐢𝐨𝐧: Do you prefer to use a bagged seed-starting mix, or would you try mixing your own?

If you’ve started seeds before, what’s been your biggest challenge: mold, gnats, slow sprouting, or leggy seedlings?

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