5 Seed Starting Mistakes to Avoid This Year
Growing a plant or crop from seed is such an incredible achievement. It’s a true testament to your dedication as a gardener, and there’s nothing quite like the pride of nurturing a tiny pebble-sized seed into a thriving, productive plant. But as rewarding as it is, it’s not always easy to get it right.
Not every gardener feels this way, but I can’t help getting overly excited to jump-start each growing season. Whether it’s the promise of harvesting fresh produce or the joy of creating a beautiful outdoor retreat, I’m always eager to start planting seeds. But here’s the thing—each seed has its own unique needs.
Planting too deep, not deep enough, overwatering, underwatering, inadequate sunlight—the list of potential pitfalls is long. Paying attention to the specific requirements of each seed variety is key to a successful garden. Let’s explore a few of the most common seed-starting mistakes, learn from my mistakes, and how to avoid them.
Planting Depth
The first time I tried starting basil from seed, it was disappointing. Despite following the instructions on the packet, my basil never germinated. One of the main reasons was how deep I planted the seeds.
Basil seeds are very tiny—similar to lettuce, tomato, and thyme seeds. All seeds have a limited amount of energy stored inside them within the endosperm to help complete germination and develop leaves capable of photosynthesis. It’s like being brand new to life with just enough strength to lift your head a few inches—we’ve all been there at some point. Larger seeds, like those of pumpkin or squash, have more stored energy and can push through the soil with ease. But basil seeds, when planted too deep, don't have the energy to break through. If I had planted basil seeds at the same depth required for pumpkin seeds (about 1 inch), they wouldn’t have had enough energy to tunnel through even a thin layer of soil.
For me, what I thought was 1/4 inch was likely closer to 1/2 inch. With seeds that small, it’s easy to misjudge depth. If the seed is planted too deep or too hard against the soil, it won’t germinate at all.
To Avoid This, sprinkle basil seeds lightly on the surface of the soil, then cover them with a thin layer and water gently. This gives them just enough protection without forcing them to push through too much soil. Always follow the seed packet’s guidelines for optimal depth, and if space allows, sow extra seeds to improve your chances of successful germination.
I also recommend experimenting with different methods to find what works best for you and your garden. When I start seeds indoors, I often sow the same type of seed in several trays or cells, even if I only want one plant. This increases the likelihood of germination and ensures that I have healthy seedlings ready for outdoor planting.
Right Idea, Wrong Time
In the past, I’ve gotten so excited about gardening that I set mental goals for growing specific plants—without properly planning. This led me to start seeds outside their ideal growing season, setting myself up for failure. Sure, there were times when the seeds still germinated and the plants grew, but they could’ve thrived so much more if planted at the right time.
Let’s revisit my basil seeds. I thought I was doing a good job, honestly. In 2023, I was beyond thrilled to build my own raised bed and purchase a tall herb planter. But I got ahead of myself. Not only did I sow the seeds too deep, but I also planted them outdoors near the end of the recommended season for my zone. By then, the weather was warming up, and even if I had planted them at the correct depth, the seedlings would’ve been too weak to survive the rising temperatures. When planting late in the season, it’s often better to just visit a local nursery or family-owned produce stand to buy stronger seedlings.
To Further Avoid This:
Take note of the frost date estimates for your growing zone. For example, in Zone 7a, my frost dates for 2025 are April 11-20 for the last frost and October 21-31 for the first frost. These dates help guide when to start your seeds.
Always check the information on your seed packet and do additional research on the variety if needed.
If you planted too early, starting another round of seeds might help.
If you planted too late, it’s better to cut your losses and buy seedlings from a local business.
Watering
As an experienced gardener myself, watering can still be a challenge to get right. Watering is crucial when seed starting; any small mistake can cause seedlings to wilt, die, or never germinate in the first place. I’ve made the mistake of over- and underwatering, which has produced poor seedlings. Here are a few common issues when watering your seedlings:
Underwatering - seeds need constant moisture to fuel their growth. Without this, the seedling’s growth is halted and can stunt or kill it. Imagine your soil is a wrung-out kitchen sponge—it’s not too wet and not too dry—this is the sweet spot for your soil. Misters can be very helpful when starting seeds to provide even coverage of moisture without bogging the soil down.
Overwatering - anything in abundance can be a bad thing. Too much water will drown your seeds and lead to fungus or air circulation issues. Seedlings can rot very easily, which is why it’s important to keep an even layer of moisture on your soil that isn’t oversaturated or bone dry. I usually use my fingertip to burrow just beneath the soil surface to check for moisture content. If my fingertip is dry, I need to water. If it is caked in overly wet soil, I need to not water. The containers you started your seeds in also need to have drainage holes at the bottom to allow excess moisture to escape and not become trapped.
Damping-off is caused by a fungus that makes seedlings wilt and die, starting near the base of the soil. This is a very frustrating dilemma when seed starting and can set your garden plans back by weeks. It occurs when seedlings are overwatered and the soil lacks proper air and oxygen circulation. It is important to thoroughly clean previously contaminated supplies like shovels, soil, or seed trays to give your seedlings the best chance against this. If you believe your seedlings have this—soggy soil, soft, mushy, or discolored stems, lack of growth—replanting in fresh, uncontaminated soil and sprinkling cinnamon on the soil surface can help. Cinnamon is a natural antifungal and will not harm your baby plant’s growth.
Inconsistent watering - in the past, I’ve overwatered my seeds and then waited a day or two before watering them again. Although I successfully avoided fungal growth or heavy, wet soil, my seeds experienced a high level of stress. The inconsistency of watering caused some seeds to never germinate and future seedlings to not be as strong and healthy as they could have been. Sticking to a watering schedule and checking moisture levels daily ensures even and consistent watering. If you want to invest in better seed starting supplies, bottom trays are incredibly useful. When not using a mister, I pour water into a bottom tray under all my seedling cells with drainage holes. The soil easily drinks up the water without drowning the seeds or seedlings and keeps the water evenly dispersed between all the cells.
Temperature & Where to Water - ensure the water is at room temperature and not overly hot or cold. The wrong temperature can rot or shock the seedlings, which doesn’t get your garden off to a good start. Also, verify you water at the base of the seedlings, right at the soil, or use a bottom tray for watering. Water that is allowed to consistently sit or splash onto the leaves of any seedling or fully grown plant will cause rot and fungus.
Helpful Tools:
Soil
Investing in a good seed-starting mix is important for optimal seedling health. You don’t need the most expensive or fancy seed-starting mix—just something that gets the job done. You can purchase an organic seed-starting mix or even create your own. One of my garden goals this year is to make my own mix for healthier plants—see recipe below.
In the past, I used regular potting soil. While it worked to an extent, the majority of my seedlings didn’t thrive. Potting and garden mixes often contain larger organic materials like wood chips, which can make it difficult for small seedlings to grow. If you’ve had success using potting or raised bed mixes, I highly recommend using a sieve or sifter to remove the larger materials. This will leave you with a fine, loamy soil that’s perfect for starting seeds. If you prefer to build your own sifter, you can repurpose leftover 2x4s and attach very fine hardware cloth with nails or staples.
The goal for seed-starting soil is to ensure it’s light and free of large materials so delicate roots have proper air circulation and room to grow.
Simple, easy to make seed starting mix:
Off-the-self, organic seed-starting mix, add 5-7% worm castings by volume (1 quart for 16 quarts of mix) - A little goes a long way! Worm castings provide a gentle boost of fertility to help seedlings get a strong start.
Creating your own from scratch - 1/3 part for each ingredient
Pumice or Perlite for aeration and drainage, which helps prevent overwatering or damping-off.
Quality Compost to add fertility and minerals to the soil
Brick of Coir is compactable, airy, and provides water retention for constant moisture. Before mixing in, expand it with some water and break apart.
Hardening Off
Hardening off is one of the most important steps when seed starting, yet it’s a step many beginner gardeners overlook. Think of it like this: Imagine being new to life, enjoying a cozy, stable indoor environment, and then suddenly being thrust outside under the blazing sun, gusty winds, and unpredictable weather. It’s rough out there! Gradually exposing your seedlings to outdoor conditions is essential. This process not only helps prevent them from dying but also signals the plants to grow stronger, sturdier stems that can withstand harsher conditions.
You can begin hardening off your seedlings once they reach about 1–3 inches tall. Keep in mind that leggy seedlings—those with weak, thin stems—often result from poor lighting or insufficient acclimation. Starting the hardening-off process early can help prevent this. Personally, I begin hardening off my seedlings while they’re still small, even if I won’t be transplanting them into their permanent garden spots for a few weeks or even a month. This early exposure helps ensure they’ll be strong and ready when the time comes.
Using an oscillating fan can be key at mimicking wind, helping prevent leggy seedlings, and even aids in preventing soil surface fungus or mold. Start this while they are still indoors or if the weather is too poor to begin outdoor hardening off.
Choose a mild-weathered day without too much heat, wind, or rain.
Place the seedlings in a sheltered spot for about 1-2 hours.
Consider any wildlife that may harm your seedlings when choosing a location.
Increase the time your seedlings are outdoors every 1-2 days.
Keep in mind that the outdoor climate may increase or decrease different needs of the plants, like water or light. Pay attention to your seedlings and regularly check the soil each day.
Avoid any overly harsh days with frosts, heavy rain, strong winds, etc. as this may kill your seedlings.
After about 1-2 weeks—and if your seedlings are strong enough—consider leaving them out overnight for another week (temperatures above 50F).
Once you notice your seedlings appear ready and are at their correct size for transplanting, move them to your garden!
I know all of this might feel overwhelming or like a lot to remember, but don’t worry! You can always come back to this guide or others whenever you need. There’s no pressure to have it all figured out right away—I still make these mistakes sometimes, and it’s perfectly normal. Even if you don’t follow every tip, you’ll still be able to grow seedlings for your garden. Aiming to implement just 50–75% of these suggestions can still make a big difference, helping you maximize your harvest and achieve more success than without these tips and tools.
I’d love to see what you’re working on! Feel free to share your progress or ask any questions in the comments. Happy gardening!
Some Images by FreePik.
