Starting seeds inside gives you a head start on your growing season, especially for vegetables that do not transplant well. But it takes care to make sure your seeds are getting the right conditions.
Start by reading the seed packet to find out their recommended planting time. Then set up a warm growing environment and disinfect your trays, containers, and tools to prevent pathogen issues.
Keep Seeds Moisture-Rich
Whether seeds are kept in a seed packet or planted in soil, they need to stay moist to germinate. Too little water leads to rot, while too much water can soften the outer seed wall and make it difficult for the seed to break open.
If you have a good quality potting mix that drains well, the seeds should germinate easily and quickly. A nutrient-filled planting medium that’s lightweight will also allow the root system to grow quickly.
Depending on the type of plant, it may take days to a month or more for seeds to sprout and grow into seedlings that are ready to transplant to the garden. Read the seed package to find out how much time to give yourself. The package will also suggest an optimal growing environment, including light and water needs. Often the recommended growing medium is not potting soil but a lightweight, fine-grained seed-starting mix. It will also indicate the soil temperature that’s best for germination.
Keep Seeds Lightly Watered
Once you have placed your seeds in the seed starting container, lightly cover them with soilless seed-starting mix. (Check the seed package for details on this, as some seeds need to be planted closer to the surface than others.)
Use a kitchen sieve to evenly distribute the seed-starting mix over the top of each cell. Covering the seeds may not be necessary, depending on what you are growing, but it helps to protect them from insects and reduces evaporation of water from the soil or compost.
Begin watering the seeds lightly from the bottom and then gently tamp down with your hand or a spoon to eliminate air pockets. Avoid over-watering or the seeds may rot or become moldy. The best seed-starting mixes contain peat moss or coconut coir, which are fine in particulate size and can wick up water to the seeds and seedlings. They also are lightweight, allowing the seeds to be easily moved without damaging or compacting the seed starting medium.
Keep Seeds Warm
Some seeds, such as vegetables and some flowers, require warmth to germinate and grow. Look at the back of your seed packet to see if there are instructions that tell you whether the plant should be started indoors or not, and when to do so.
If there aren’t any, you can start most warm-season plants around eight weeks before the last expected frost date in your area. This allows enough time for the plants to mature before summer heat stifles growth.
Once you’ve planted your seeds, they need to be kept in a warm spot where they won’t be disturbed or moved too often. Use a plastic wrap or, if your seed trays come with a lid, put one on top to keep moisture in and the temperature stable. It’s important that the soil stays moist, but not wet, so mold doesn’t grow. If mold does appear, Fine Gardening recommends a couple of simple steps to correct it: withhold water for a few days and increase air circulation by using a fan or opening a window.
Keep Seeds Clean
When it comes to seeds, cleanliness is key. A dirty seed packet will not be able to retain moisture and remain dormant like a clean one. The same goes for storage containers. Paper bags are humidity-permeable, while plastic ziplocs and plastic food containers are considered fairly airtight, although not as much as glass or metal containers with lids.
Once you’re ready to get started, remove your seeds from cold storage and set them down somewhere away from direct sunlight. Let them sit for a few days to reach ambient room temperature before opening. Rapid temperature changes can cause moisture to condense inside your container and spoil the seeds.
Once your seeds are at room temperature, take a bowl of the soil you will be using for sowing and mix in a little water to moisten it. It’s best to wear a face mask when doing this, as the seed-starting soil is fine and can irritate your nose and throat.