The experience of growing a sweet, luscious summer tomato from seed is one I want everyone to have. I’ve developed this basic growing guide to help you get started growing from seed, but don’t forget to subscribe to my newsletter for even more tips and tricks throughout the growing season.

When should I start my seedlings?

When to start seeds depends on your garden zone and last frost date (find your garden zone and frost date HERE). On most seed packets, they have recommended starting dates for growing from seed. For example, they say to start tomatoes indoors 6 weeks before your last frost date. In my zone, I don’t usually follow the advice on seed packets because they are often written for gardeners in colder climates. I highly recommend finding a local gardener and seeing when they start their seeds. For example, gardeners who are in Southern California and similar mild climates are welcome to view my personal seed schedule that I include at the bottom of my subscriber newsletters. Most importantly, know your garden zone and do some online research for planting schedules for your zone. Your local Master Gardeners Extension can also be a great resource (just search your county and “master gardener extension”).

Related Article: Where I Buy Seeds ~ My favorite Seed Sources!

Seed starting media

There are different options for what type of soil/media you can use to start seeds. The two I work with most are: seed starting mix or peat pellets. As a beginner, I used peat pellets because they took up very little space, were clean, and easy to understand. As I started to grow more and more, I started using a seed starting mix for my seeds because it ended up being more budget friendly and customizable. The choice is yours, but remember that growing from seed is a process you’ll learn to refine over time to fit your needs.

TIP for Seed Starting mix: It’s important to use a mix specifically designed to start seeds like this one. These mixes retain better moisture, and are light and fluffy enough to allow the sprouts to push through. You can also make your own seed start mix.  You can see my DIY seed starting mix recipe in this article with a video tutorial.

Peat pellets (which can be found here) can be a great option for beginners or those gardening in small spaces.

Pots, Trays, and Cells for Starting Seeds

If you are using a seed starting mix, you’ll need seed starting trays or pots to fill with your mix. In all my years growing from seed, I have finally found seed trays that are durable, re-usable, and make it easier to remove your seedling to transplant. Unlike products that become crushed or split over time, these seed starting products from Epic Gardening are hardy and made in the USA: I’ve been using both the 6-cell seed trays and the 4- cell trays.

Germination

The first step in growing from seed is getting those seeds to germinate! By the way, “germinate” is just a way of saying “sprout” or beginning to grow. In order for most seeds to germinate, they simply need some warmth and moisture. I cover a few different methods for how to raise seedlings depending on your climate, but I now have an Indoor Seed Setup breakdown for those of you who want a very simple way to start seeds indoors.  Assemble your seed starting media, seeds, and get ready to plant!

Take note of the “seed depth” listed on the seed packet. This is how deep you need to put the seed in the soil.

You can place 1-3 seeds per hole if you would like, or spread your seeds out around the entire pot/pellet. Later in this process you can thin out the extra seedlings.

Make sure to label your seedlings. There are many options here. Some people use popsicle sticks, or you can can write them all down in a grid format/spreadsheet that corresponds to your tray. You can also checkout my DIY milk jug seed labels. Whatever you do, just remember to label!

Related Article: Fall & Winter Gardening Guide for Southern CA

Once your seeds are nice and cozy in the soil, observe them to see when they sprout and break the surface of the soil. The ideal temperature for seeds to germinate is between 60-80F. This is why the seeds do well when started indoors before Spring. Most of the time, our homes have temperatures in this range.

Once your seeds sprout, it is time to start giving them light. Note: if you are growing using a peat pellet greenhouse kit, the lid needs to be propped or offset once you see the first sprout. This allows some air flow and will prevent molding, dampening off, and other problems.

Lighting

Finding adequate lighting indoors for seedlings is a struggle for a lot of gardeners. I don’t have a grow light, so I’ve always had to improvise with a sunny windowsill. While this method does entail a lot more moving and chasing the light in your home, it is doable up to a certain point. I have grown seedlings on a sunny windowsill until they have produced their second set of leaves without any problems (see my note on an indoor/outdoor method below). Do what you can to find that sunny spot and check on your seedlings daily. Update 2024: I now have an indoor seed setup guide for those of you interested in grow lights and how to start seeds using a grow light setup.

Are your seedlings growing really long stems? This is called getting “leggy” and it means that your seedlings are not getting enough light (see example photo below). When seedlings get leggy, that means they are reaching for more light thus making their stems taller and weaker. The solution is to get them into more light!

♦If you are starting seeds for a Fall or Winter garden, there is plenty of light outside to start seedlings. Watch my Fall seed sow-along for more details on Fall gardening. I just find a mostly shaded area to get them started. Harsh afternoon light can burn your seedlings, but gentle morning light is good. Be wary of pests, like birds, that could try to eat your seedlings outdoors. Sometimes a covered patio works best to shelter them. You can also cover with mesh.

♦If you are starting seeds for a Summer garden, some climates (like mine) are warm enough in Spring to keep your seedlings outside during the day and then bring them inside at night (when night temps are in the 40s and low 50s).

♦If you’d like a more streamlined and convenient setup, consider an indoor seed starting setup with grow lights like this one. 

Related Article: 10 Heat Loving Flowers & Veggies to Grow From Seed

Daily Maintenance

Seedlings need to be checked daily. For many of us, this is not a problem because we are obsessed with checking on our seedlings. Haha! What are you checking for? Well, you want to make sure the soil does not dry out. The peat pellets make this easy to see because they start to turn lighter in color. Simply water as needed to keep the seedlings moist (but not sopping wet). Pro tip: water your seedlings from the bottom (like in the video below). Meaning, put water in the tray and let the pellets or pots soak up the water. Do not leave excess water in the tray. Another way to water delicate seedlings is to use a spray bottle.

The video below shows how I feed my seedlings, but the process is the same for regular watering (I just wouldn’t add the food to the water).

A second thing to do daily is to rotate your seedling tray. Your plants will naturally reach towards the light, so if you are growing on a windowsill your plants will likely be reaching towards the glass. Give your tray a 90 degree turn each day to prevent your seedlings from growing and bending over one direction. This problem is usually avoided by grow lights because they are mounted directly over the seedlings, or if it is warm enough to be growing from seed outdoors.

Thin your seedlings

What is thinning? A lot of gardeners dread this part of growing from seed (but I do not). Thinning is important. Why? If you don’t thin them out, the seedlings end up competing for nutrients and light. Once your seed babies begin to show the development of their “true leaves”—this is often the second set that emerges from the plant and usually have a more distinct shape (see photo below)—you can look to thin them down to one seedling. I simply take a small pair of scissors and cut out the seedling that looks the smallest or weakest. I know this is hard to do sometimes, but it really will help the remaining seedling flourish and grow big and strong! More on thinning in this article here.

Feeding Your Seedlings

Did you watch the video above? I feed my seedlings using a liquid fertilizer and mixing it with water. You can read additional details about when and how to fertilize your seedlings in this article here. Since most seed starting mediums don’t contain enough food to sustain seedlings past growing their first set of true leaves, it is important to feed your seedlings. I like to fertilize once a week or so, depending on how my seedlings are reacting to it.

Related Article: 5 Tips for Stronger Seedlings

If you started seeds indoors…

After all danger of frost has passed, you can begin to harden off your seedlings. This means exposing them to the “elements” for a couple hours each day in order to prepare them for a life outdoors. This process allows for your seedlings to get used to more intense sunlight, wind, and other natural exposures. Start by putting them outside for a couple hours a day but gradually increasing this time as each day goes by. Never put them in direct, intense sun. This process can take anywhere from 7-10 days, and sometimes shorter if you live in a climate like mine. You’ll get used to seeing how they react and how they are enjoying being outside. Get my 10-day plan for hardening off seedlings »»» here.

Planting Your Seedlings

Hooray! Your seedlings are hardened off and ready for planting! In the gardening world, this is also called “transplanting” into the garden. Is your garden soil prepped for your new plants? I cover how I amend my garden beds each season in Amending Your Soil Organically. 

Whenever you transplant any seedlings, the most preferred time of day is either early morning or early evening when the sun is not at the hottest. Water each transplant thoroughly after planting, and cover with a temporary shade if it is going to be extremely hot for the first few days.

I like to add some mycorrhizae to the planting hole before adding my seedling, but that is optional. You can check out my favorite mycorrhizae product from Plant Success Organics HERE and use code: randi15 for 15% off your purchase.

If you are using pellets, you should peel off the netting around the peat pellets. My package says the netting is biodegradeable, but it’s so easy to peel off and then I know that the roots can have an easier time spreading. If you choose to leave the netting, I have done this in the past and the roots still spread—-but why not give the plant the best chance possible? Peel it off.

And there you have it! A basic guide to growing from seed. Cheers and happy growing!

Other Articles You Might Find Interesting: