Seed Starting Guide

Indoor Seed Starting

Willamette Valley Oregon, Zone 8b

Direct Sow
Princess Gabi Direct Sowing Peas

Garden Jargon Glossary

  • Annuals: Plants that complete their life cycle in one year.
  • Biennials: Plants that complete their life cycle in two years.
  • Perennials: Plants that live 2+ years.
  • Direct Sow: To plant a seed in a garden bed outside.
  • Start: To plant a seed in sterile potting medium indoors.

Want to know two different methods for starting seeds indoors? Ask two different gardeners or look in two different books–and they will both be right.

For years, I have been reading articles, gardening books, and blogs and I have sifted and sorted and dialed in a system that works really well…for me. I’m going to lay out my method, for you to sift through and experiment with on the path to find your own seed starting method. 

Create a Plan to get Starting Dates (or use mine!)

My 2021 Plan

First, I list all the plants I’ll be starting from seed. Then I refer to my planting guide for starting dates and then begin to organize everything by month. Then I sort them further into lists of direct sow and starts. 

With regard to timing when to sow, there is about a 2-4 week window where it doesn’t seem to impact the outcome. I find I have more trouble when I start seeds too early (and I usually do) rather than too late. If you want to start them early—go for it. But also start a few later and compare your results. I’ve broken so many “rules” and was punished with a bumper crop. 

Gather Materials

  • South facing window and/or grow light.
  • Seeds
  • Sterile Potting Soil (some people get seed starting soil, I use cheap stuff that has served me well.)
  • Paper Pot Maker
  • Paper: newsprint or seed catalog paper (not shiny)
  • Trays
  • 4” pots for up-potting
  • Plant-able pots for cucurbits family. (cucumber, squash)
  • Craft sticks
  • Sharpie

Seed Age

Seeds lose vigor with age, some faster than others. According to the Sustainable Gardening Handbook here are some averages on how long seeds remain viable, provided they are stored in a consistently cool, dry, and dark place like a refrigerator. Silica packets in your seed containers can help keep humidity low.

Organized, but not temperature or humidity controlled.
  • 1 year: sweet corn, onion, parsnip, leek
  • 2 years: okra, parsley, 
  • 3 years: asparagus, bean, carrot
  • 4 years: beet, mustard, pepper, pumpkin, tomato
  • 5 years: broccoli, Brussels sprouts, cabbage, cauliflower, celery, collard, cucumber, eggplant, kale, lettuce, spinach

I don’t refrigerate my seeds so I discard seeds after two years. If there’s a question, I’ll germinate some seeds in a wet paper towel and try to get a feeling for their vigor. If they seem weak, or not many germinate, then I won’t waste my time with the batch. 

Indoor Seed Starting
Top shelf relies on sun, the bottom shelf has a grow light.

Southern Window vs. Growing Light

The south facing window served me well for many years, but I admit to increased vigor of seedlings under a grow light. 

Seedling heating mat?  

I’ve done fine without it, but many of my gardening friends swear by them.  I have a feeling that the solanaceae (tomatoes, eggplant, etc.) and cucurbit (cucumber, melon) family would appreciate them. They can be very helpful if germinating in a cold basement or greenhouse. 

Paper Pot Maker


I prefer to use pots made from newsprint paper. My favorite paper is from seed catalogs. I bought this Paper Pot Maker from Amazon and have made at least a thousand paper pots and still find it fun. The pots breathe well, wick water like champ, and you can plant the whole thing in your bed or in larger pot minimizing root disturbance. They take up minimal space, so you can go sow eleventy-one and pot up the strongest of the bunch or share, etc.

The Process

  1. Dump some potting soil in a bucket.
  2. Make the pots.
  3. Hold the pot over the bucket and gently fill with soil.
  4. Place in the tray.
  5. Repeat until they are all filled with soil and resting comfortably in the tray. (I’m using a Costco Apple Pie container.)
  6. Poke in your seeds. 
    • Basic rule of thumb, twice as deep as the seed’s diameter.
    • Two or three seeds per pot. 
  7. Mark with a craft stick or write on the side of the pot.
  8. Label the tray with the date started. (And note in your plan.)
  9. Water the tray two-thirds of the way up with lukewarm water.
  10. Let the water wick up the pots and refill the tray if needed. The seeds need to be wet to get the signal to germinate. Just as if they were outside in the rain. 
  11. Once the seeds sprout they need to be kept moist but no longer saturated.


Check on your seeds daily. Touch the tops of the paper; if it feels crispy add lukewarm water to the tray.  


Once the seeds sprout ensure they get the sunniest window (this might involve moving from window to window and shifting them around so they don’t shade each other.)  Or flip on your grow light. I follow the light cycle of the day.


Each seed contains enough food for the plant to put out its first set of true leaves. (Seed leaves are the first to emerge, then true leaves.) Once the reserves are exhausted they must get nutrients from the soil. In general, my potting soil is not enriched. So at this point I begin to add a little liquid food to their water. My favorite is an organic liquid called Buddha Grow by Roots Organic. Organics are better for us, the planet, and more forgiving to work with (it’s harder to over do it and burn your plants because the organics take longer to break down).


Many of your babies are going to burst out of their paper pots before they are ready to go outside. (I’m looking at you tomatoes and squash.)  Keep a supply of fresh potting soil and 4” plastic or plantable pots handy. I up-pot when the roots push through the paper and the sprout looks sturdy. I add a little soil to the bottom of the new pot, pop in the paper pot and gently sprinkle soil around the edges to fill the new pot.  

For the cucurbit family (cucs, squash, melons) use plantable 4” (or larger) pots to minimize root disturbance when you transplant. Everybody else is pretty happy in the standard 4” plastic pots until transplanting time. If you use recycled containers ensure you put a few rather large holes (1/2″ or so) in diameter for drainage.

At this point I swap the round plastic trays with sturdier metal or plastic trays.  Because I only have one grow light, I’m also rotating between sun exposure and grow light every few days. I also begin to water the pot rather than the tray. Remember to feed them at least once a week.  


After up-potting, it’s time to select for the most vigorous start. I find this process excruciating and sometimes don’t do it at all. But, I try to remember my friend Maggie Stuckey’s words from her book, Gardening from the Ground Up, “It is hard to make yourself do this; it feels wasteful and murderous. Do it anyway.”

Trouble Shooting

Yellow Leaves Mean:  They are lacking in nitrogen and need to be fertilized.  

Long Weak Stems: Leggy seedlings are searching for light. 

Wilted Plants: If the pots are dry, they need water.  If everything is already wet and your plant is droopy, then they are drowning due to over watering. Unfortunately, the symptoms look the same.  

Failure to Sprout: 

  1. The soil could be too dry. This is by far the most common issue, people are generally worried about overwatering their seeds. I’ve replanted some pots only to have the original seeds germinate when they finally got the water they needed. Oops. A cover over your unsprouted seeds will keep the humidity high.
  2. Some seeds like perennial herbs like lavender, peppermint, and onions just take a really long time to germinate.   Check your seed packet, if you’re worried.
  3. They needed cold stratification, but didn’t get it. (Many meadow flowers need this.)
  4. Is it too cold?  This is generally not an issue for indoors, but if you’re growing in a basement or greenhouse, check the temperature.
  5. The seeds could be duds. (Seeds lose vigor with age and if they are exposed to temperature fluctuations.)
I love my garden babies! 💚

2 responses to “Seed Starting Guide”

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