A Beginner’s Guide to Starting Seeds and Transplanting Seedlings

Gardening will never stop being miraculous to me. You start with a tiny seed, sometimes the size of a pin head, and with a little time and care, you end up with a basket full of tomatoes, or a handful of fresh basil. It is something that I find deeply satisfying in a way that nothing else is.

If you’re new to growing from seed, the process can feel a little intimidating. There are timing windows and grow lights and terms like “potting up” and “hardening off” that nobody explains until you are already in the thick of it and confused. At least that was my experience when I started gardening over a decade ago. This post (and others on this site) are meant to be a practical guide to gardening.

If you prefer to watch rather than read, here are the two “beginner” videos that will get you from seed selection to plants in the ground. I will have more in depth videos soon, but these are what I wish I had when I was getting started. Scroll if you want to keep reading!

Before You Start, Know Your Zone

Everything in gardening starts with knowing your growing zone. In the US, you can find it on the good old Farmer’s Almanac. Click here and enter your zipcode to find yours. You can also just do a search for the growing zone you live in. This will give you average temperatures and tell you when you can start planting outside, what plants will grow for you based on temperature and length of growing season, and possibly particular varieties that do well and native plants.

I garden in zone 6b/7a – I’m right on the line. If you’re in the same zone, the general advice for warm-season crops is to wait until Mother’s Day weekend to transplant outdoors. A late frost can wipe out weeks or months of hard work and break your heart. Ask me how I know. Waiting an extra week is always better than losing your seedlings.

Seed Starting Indoors

Most warm-season vegetables like tomatoes, peppers, squash, and many flowers need to be given a head start indoors several weeks before the last frost date to give them long enough to grow to their full potential. But sticking seeds into dirt and placing them by a window probably isn’t going to give you the best results.

What You’ll Need

• Not regular potting soil. Seed starting mix is lighter and finer, which gives delicate roots room to grow without compaction.
• Seed trays, small pots, or repurposed yogurt containers or solo cups with drainage holes all work. The container matters less than the drainage.
• Seeds germinate faster with bottom heat. A seedling warming mat makes a noticeable difference, especially for peppers which are slow to sprout in cool conditions. (This one is not absolutely necessary, but I get much better results with)
• A south-facing window can work, but a dedicated grow light gives you much more control and prevents the leggy, stretched seedlings that happen when plants reach for insufficient light.
• You WILL forget what you planted. Label everything immediately. A permanent marker and a popsicle stick is all you need. I promise you I still get at least one mixed up every year 😂

Reading the Seed Packet

The seed packet is your instruction manual and most people don’t read it carefully enough. Here’s what to look for:

• How long before you’ll see sprouts. Set expectations accordingly — peppers can take two to three weeks. Days to germination
• How long from transplant to harvest. Important for planning your season. Days to maturity
• How deep to plant the seed. Usually two to three times the seed’s diameter. Planting depth
• How many weeks before last frost to start seeds inside. This is your key timing number. Start indoors
• Full sun, part shade, etc. Plan where in your garden each plant will go. Sun requirements

The Seed Starting Process

1. Fill your containers with moist seed starting mix- damp but not soggy.
2. Plant seeds at the depth indicated on the packet. Most go about a quarter inch deep.
3. Label immediately. Every single container.
4. Place on your warming mat and cover loosely with plastic wrap or a humidity dome to retain moisture during germination.
5. Check daily. Seeds move incredibly fast when they are ready and need consistent moisture to germinate. Don’t let them dry out.
6. Once sprouts appear, remove the cover and move under your grow light. Aim for 14-16 hours of light per day. More and they will get a sunburn! Ask me how I know 😂
7. Water from the bottom when possible — pour water into the tray and let the soil absorb it. This prevents damping off, a fungal condition that kills seedlings at the soil line.

Potting Up

When your seedlings have their first true leaves (the second set of leaves that appear, which look like miniature versions of the adult plant’s leaves) it’s time to pot up into a larger container. This gives roots room to develop before transplanting outdoors.

• Move seedlings from seed trays into 3-4 inch pots filled with regular potting mix
• Handle seedlings by their leaves, never their stems. A broken leaf recovers, a broken stem doesn’t. (sometimes you can bandage a tomato and it will be okay, that’s a post for another day!)
• Water well after potting up and return to your grow light
• Repeat if plants outgrow their containers before it’s time to go outside

Transplanting Seedlings Outdoors

This is the step that makes new gardeners most nervous, but plants are genuinely more resilient than we tend to give them credit for. A few simple practices make the transition smooth.

Hardening Off

Seedlings grown indoors have never experienced direct sun, wind, or temperature fluctuation. Putting them straight into the garden is a shock to their system. Hardening off is the process of gradually introducing them to outdoor conditions over one to two weeks.

1. Start with one to two hours of outdoor shade per day.
2. Gradually increase outdoor time and sun exposure over 7-14 days.
3. Bring plants in if temperatures drop below 50°F or if frost is forecast.
4. By the end of the hardening off period, plants should be spending full days outside.

Transplanting Step by Step

1. Choose a cloudy day or transplant in the evening to reduce transplant shock from direct sun.
2. Water your seedlings well before transplanting- hydrated plants handle the move better.
3. Dig a hole slightly larger than the root ball.
4. For tomatoes specifically: plant deep, burying the stem up to the lowest set of leaves. You might even pull off the bottom set of leaves before planting to get them a little deeper. Tomatoes grow roots along their buried stems and this gives you a stronger plant.
5. For peppers, herbs, and most other seedlings: plant at the same depth they were growing in their container.
6. Firm the soil gently around the base of the plant to remove air pockets.
7. Water thoroughly immediately after planting.
8. If the forecast threw a curveball and frost is possible in the coming days, have row covers or old bedsheets ready to protect your plants overnight.

After Transplanting

• Water regularly for the first week. Roots are establishing and can’t reach deep moisture yet.
• Don’t panic if plants look wilted for a day or two. This is normal transplant shock and they almost always recover.
• Hold off on fertilizing for the first week or two. Let roots settle before pushing growth.
• Mulch around plants to retain moisture and suppress weeds.

Now trust it.

Plants want to grow. That sounds obvious but it’s easy to forget when you’re hovering anxiously over a seedling that looks a little sad after transplanting. You’ve done the work — given it soil, water, light, and time.

Gardening is one of the few things that genuinely teaches patience in a world that doesn’t reward it much. Your job is to show up, pay attention, and get out of the way.

More details and videos to come, but I truly hope this is helpful.

Let me know if there is something specific that you’d like an article or video about! Happy planting!