Start with good-quality seed.
Starting with quality seed is the most important step in a successful seed-starting endeavor. Look for seeds that have been untreated and are non-GMO, as well as disease free. Buying seeds from a reputable company guarantees that the seeds will be healthy, viable and of a good quality. If you do buy seeds online, read the reviews to learn what other gardeners think of them before you buy. For best results, choose varieties that are native to your local area so they will acclimate well once transplanted outside.
Water the soil, not the seeds.
Watering seeds is like watering any other type of plant: you should always water the soil and not the seeds themselves. Watering too much can cause the seeds to rot, while watering too little will stunt their growth.
Remember that all seeds are different and require unique maintenance, but most seedlings will need to be watered at least once per day. Seeds that require more water include those from squash and cucumber plants, while plants like peppers require less frequent watering.
Avoid over-watering or overwatering.
Watering is tricky because it’s so easy to overwater, which can kill your seedlings. Don’t let your pots dry out, but don’t keep them sitting in water. It can be difficult to judge how much moisture the soil needs—you want it moist at all times without being soggy. If you’re not sure, just add a little water at a time until the soil is damp. To make watering easier, try using a watering wand with an adjustable flow: The sprinkler head offers wide or narrow spray patterns for efficient watering, and let’s you water up close to plants without getting wet!
If you’d like more help adjusting the amount of moisture in your soil, consider purchasing a moisture meter (available from garden supply stores). They will tell you if it is too dry or too wet.
Use a heat mat for best germination results.
- Heat mats provide the bottom heat that seeds need to germinate. Place trays on a flat surface, ideally in a room with good light and where the temperature can be controlled.
- Once seeds have germinated, move them to a cooler area with bright light. This will prevent seedlings from growing too quickly and becoming leggy. If you’re using artificial lights, raise them as seedlings grow or they may get too close and burn.
Plant the right amount of seeds.
Every seed packet looks different, but most include a table at the back that will tell you how many seeds the package contains and how many plants you should expect those seeds to yield. It’s tempting to plant only as many seeds as you think you will need, but that decision is one you may end up regretting. Seed germination rates vary from year to year and even from batch to batch, and they can be affected by a number of factors, including temperature fluctuations in your home or sunlight levels. If your seedlings don’t emerge with the expected rate of success, or if some get damaged while thinning or transplanting them into individual containers, you won’t have enough healthy seedlings for all of your garden beds. Plant extra seeds to ensure that if any don’t germinate or are lost during the seedling process, you will have plenty of backups. And don’t worry—if all goes well and almost every one of your seeds grows into a healthy plant (as it should), it is easy to thin out your seedlings later on down the road.
Add a little food to their diet.
To give your seedlings a nutritional boost, add a balanced fertilizer to their diet. A light application of one-quarter strength is all they need as they’re just starting out (and/or if you’ve already added fertilizer to the soil mix). You can add it to the water you use for watering or mix it into the soil.
It’s OK if the food runs off a bit, but don’t let it sit in a pool of water or the roots may rot. Apply once every couple of weeks until you transplant them outside.
Keep them warm and out of drafts.
While seedlings grow, they need warm soil. Most will do best in a spot where the temperature is between 70 and 75 degrees Fahrenheit, but this number varies with each type of plant. It’s not always possible to keep your seedlings that warm, especially at night. If it’s cold at night, try keeping your seedlings in a partially closed (cracked open) room or tent them with plastic.
If you have hot days and cool nights, don’t put your seedlings outdoors during the day unless it’s sheltered from wind and direct sun. Keep an eye on them—if the soil gets too dry, water lightly; if it stays moist all day long, you have too much cover or protection.
Seedlings should not be moved into direct light until the second set of true leaves opens up—the first set are called cotyledons (or ‘seed leaves’). When moving them into sunlight for the first time, increase their sun exposure gradually to help prevent burning their leaves.
Make sure they have enough room to grow.
Seedlings don’t need much space at first. But as they grow, their roots will become crowded, which can stunt growth and cause your seedlings to dry out. So give them enough room to grow right from the start by using an appropriately sized container. The size of the container should be equivalent to the size of the mature plant’s root system.
A typical 6-inch seedling tray is great for a single tomato, pepper or eggplant seedling, but makes it difficult to grow multiple plants in a small space like a windowsill. Instead, you may want to use larger containers, such as shallow 2-inch pots or six-packs with drainage holes (which you can easily make by cutting apart four-packs). Larger pots allow plants more room to develop good root systems before being transplanted outdoors; once transplanted outdoors into your garden soil, those well-developed root systems will help plants adjust more quickly and produce bigger yields earlier in the season.
Starting out seedlings is all about creating a nurturing environment for your plants to grow in.
If you’re new to starting seeds, you might be feeling overwhelmed by all these different things: how much water to give them, where the light should go, and just what kind of food the seeds need. Well, let me kick your baby-starting experience up a notch by sharing some tried-and-true tips.
…Water is vital for starting seeds; they simply won’t grow without it. One important rule of thumb is that you don’t want the soil to get dry (or at least not very dry) before watering again. When that happens, you’ll see bad consequences—your seedlings are more likely to drop their lower leaves or show signs of stress (such as wilting). Make sure that the pot still has moisture in it after watering. You can tell if the soil needs water when it’s still damp but not soggy.
…Light is also important for starting seeds—it’s all about giving them enough of everything, including nutrients and natural sugars from decomposing organic matter below ground (which also helps speed germination), as well as carbon dioxide from woody plants, so that they can photosynthesize and grow. But if your windowsill doesn’t get direct sunlight all day long, consider putting a grow light under the pot of growing plants to help supplement their daily lighting requirements.
…You can encourage root growth with some moistened compost on top of your growing medium; this holds in moisture and releases nutrients into the soil over time. Remember to add compost back into your growing medium after every watering cycle so that it doesn’t mold or become overly acidic over time (a good indicator is when your seedlings stop taking acid drops right before they germinate).
…The third key component needed by a seedling is adequate nutrition: start with a fertilizer made specifically for seedlings that contains nitrogen (the building block for green leafy growth), phosphorus (needed for root growth), and potassium (which makes roots harden off quickly).