I began my seed-starting journey 20+ years ago. Down in our farmhouse basement, I would help Mom get a few trays ready starting with soil, adding seeds, and placing them under some lights hanging from the ceiling. I remember running to check them every day, eventually seeing something poke through, its growth making itself known to the world. That is seed starting! A pretty simple process:
- Take a seed.
- Place it in soil.
- Water it.
- Watch it grow.
At its core, seed-starting is super easy and pretty much painless. The challenge can stem from all the factors and variables that affect the way a seed grows.
Here’s the simple way I go about starting seeds with all the questions I’ve ever had and the answers I’ve learned.
Why start seeds?
The first question a lot of people ask is “why should I start seeds as opposed to buying the plants at a garden center?” There are a couple of reasons:
- When you grow from seed, you have so many more options and can choose the variety of plant you want. For example, you won’t be stuck with an in-stock red tomato. Instead, you can choose an heirloom variety with superior flavor.
- You control how they are grown. Many plants at garden centers can be raised with neonicotinoids which is an insecticide that makes growing plants easier for large growers. But this can be harmful to pollinators once planted in your yard. When you grow plants from seeds, they can be 100% organic.
Where do I start?
Seed starting is exciting and can be overwhelming. I start by separating my seeds into two categories:
- Ones to start indoors
- Ones that are directly planted in the garden without the need for indoor germination
When do you start seeds?
This is variable and changes depending on where you live. As a general rule, seeds can often be started about six weeks before your last spring frost. In the United States, begin by searching for your last spring frost date. This is the date where the chances of getting a “killing frost” are almost zero. The date is determined by your location and weather. Knowing your last frost date will allow you to work backward to create a timeline for seed starting.
Some seeds can be started earlier and can take cooler temperatures. These include:
- head lettuce
How do I know when to plant each specific type of seed?
The back of a seed packet is your key for this and has a lot of vital information on it:
- depth to plant the seed
- whether it should be sowed directly in the garden or started indoors
- the days to germination
- the weeks to transplant outside
- the weeks to harvest
Do I need grow lights?
Not necessarily. Grow lights are ideal but not required. These special lights provide a stronger, consistent light to seedlings. Strong light will help the seedling become stronger, grow straight, and have sturdy stems.
If you do not have grow lights, small amounts of seeds can be grown on windowsills. But the strength of the sun and the amount a seedling will receive early in the year will likely not be as much as the seedling desires.
Can I use any soil?
Short answer: no. Seedlings have very delicate roots and need to be able to break through the soil easily. The roots also need plenty of oxygen to remain healthy. For both of these, seed starting soil is essential. This special soil will not have any fertilizer and is very light and airy. The soil is formulated for seeds to easily germinate and grow.
What do I do once the seeds sprout?
When seeds first break through the soil, it can prompt panic for someone growing them for the first time. These seeds were just fostered and grew: now what? All seeds have the same two leaves at first, called cotyledons. These tiny leaves are the first source of photosynthesis for the plant, helping establish the roots and getting the plant started.
Once the cotyledons have appeared, remove the clear lid, and if using lights, lower the lights to within four inches of the seedlings.
How do I water and fertilize?
As soon as the seeds sprout, the roots have started to grow. The roots take in water and it’s important to water the soil if it’s feeling or looking dry.
Plastic seed starting trays with cell pack inserts are designed to be watered from the bottom. When water is poured into the base of the tray, the cell packs soak it up without disturbing the seedlings and soil on top. Mist the tops with water and, if you must, water from above use a water breaker to give a softer waterfall.
Fertilizing can be tricky for seedlings and can burn them easily. Once the true leaves have appeared and the cotyledons have gone away, fertilize every other week at half strength. Use an organic fish emulsion or seaweed fertilizer. Alternatively, an all-purpose 10-10-10 fertilizer can be used at half strength.
Watch how to start seeds:
How to Start Seeds for an Early Spring Garden
- Seed starting tray without drainage holes
- Clear lid for seed starting tray
- Cell inserts for tray
- seed starting soil (no fertilizer added)
- Start by pre-moistening the soil. Add water until the soil feels damp but not heavy. I find it best to slowly add water and mix the soil to make sure it is evenly moistened.
- Add the pre-moistened soil to the seed starting cells. Press the soil slightly to ensure each cell is filled with soil.
- Using a fingertip or the end of a pencil, make a small hole in each cell according to the seed's planting depth instructions (see back of packet for specifics).
- Add two or three seeds to each hole. Adding multiple seeds will increase the probability of germination and extras can be easily removed later.
- Cover seeds with displaced soil. Add a thin layer of vermiculite on top of the seeds to prevent condensation from sitting on the soil.
- Spray with water to ensure the seeds have moisture and cover with a clear lid to create a small greenhouse. Place under grow lights or in a window that receives a large amount of sun.
- Check daily to ensure condensation is inside the clear lid. This means the seeds have the moisture they need. If the lid is dry, spray the soil with water.
- Once the seeds break through the ground, remove the lid and keep the grow lights four inches from the seedings.