Seeds can be started indoors or outdoors. Start seeds outdoors only when the temperature is right for the certain seed. Different seeds germinate at different temperatures. Cool-weather crops tend to germinate at lower temperatures, while warm-season temperatures germinate at higher temperatures. For example, onion, parsnip, spinach, and lettuce, can sprout at as low a temperature as 35F, while squash, watermelon, and cucumber need at least 60F to germinate.
To start seeds:
- Start the seeds at the right time for the seedling to be ready to plant out when the weather is favorable. Seeds can be started indoors or outdoors. If you sow seeds before the last frost, start them indoors. If you start seeds outdoors, start them after the last frost date.
- Get the seeds ready
- Prepare the right containers for the seeds to germinate. Almost any type of container with a depth of at least 2.5 inches will do. Seed containers must be able to hold soil well, drain well through the holes on the bottom and allow space for the roots to grow.
- Prepare the soil, seed starting mix, or potting soil
- Sow the seeds
- Water your seeds
- Germinate your seeds at the right temperature
- Provide adequate light once your seeds germinate
- Feed the plants if needed
- Harden your seedlings off before planting them outdoors
- Plant the seedlings once the weather and the soil are right
When to start seeds indoors
Start seeds of cool-weather vegetables about 10-12 weeks before the last frost date so they can be ready to be planted outdoors around 4-6 weeks before the last frost date. Start seeds of warm-weather vegetables around 4-6 weeks before the last frost date so they can be ready to be planted outdoors right after your last frost date. Plant the seedlings outdoors when the soil is thawed, the right temperature for the specific seedlings, and the weather temperatures are favorable for the specific seedlings. If needed, protect young seedlings from occasional frost by covering them with frost protection.
I start my seeds indoors with the hardiest pantry staple vegetable like an onion. They will be planted outdoors first. Couple weeks after sowing onion, I start my other pantry staple vegetables like leafy greens such as lettuce, arugula, Swiss chard, cabbage, cauliflower, and broccoli.
TIP: If you want to grow sweet potatoes from slips, you can start your sweet potatoes very early, about two months before the last frost. They start to spout about 2 weeks after being buried in soil indoors and the slips take about 6 weeks to be fully ready. Different varieties of sweet potatoes start to sprout at different times. I would recommend starting your sweet potatoes at least 2 months before planting. In general, they like warmer soil, so I would recommend planting them after the soil warmed up well.
When to start seeds outdoors
Start seeds outdoors when the temperature is right for the seeds to be planted outdoors. The soil should be thawed, workable, and not too wet and the temperature should be as the specific seed requires. Check the seed packaging for the temperatures when the seeds can be planted outdoors. Seeds of cool-weather vegetables are to be planted outdoors first. Some can be planted outdoors even before the danger of the last frost is over. Seeds that can be sowed outdoors about 4 weeks before the last frost are onion, carrots, parsnip, beets, Swiss chard, spinach, lettuce, arugula, radish, turnips, and peas. Even potatoes can be planted. Potatoes however might need to be covered with frost protection if the frost hits your location at night. Warm-weather vegetables can be sowed directly outdoors after the last frost date and when the soil temperature has reached the ideal temperature for the seeds to germinate. Warm-season pantry stocking vegetables that can be sowed outdoors after the last frost are tomatoes, peppers, cucumbers, watermelon, corn, beans, zucchini, squash, and pumpkin.
Each gardener should know in what hardiness zone he or she is located, to know when to sow seeds indoors and outdoors. I have written an extensive article to help you understand what hardiness zones are and how to find out your hardiness zone. Knowing your hardiness zone will help you determine your first and last frost date, and what plants to sow when. Click on What hardiness zones mean and how to determine yours, and enjoy the good read!
Where to get seeds for the garden
Seeds can be purchased at your local garden center, or nurseries, many grocery chain stores carry them, and farm and hardware stores too. You can even get some seeds at dollar stores. Seeds can be purchased online at seed stores. Check your local library, they might distribute free seeds to local gardeners, and some libraries do.
How to choose seed starting containers
If starting seeds indoors, one will need contains to start seeds in. Seeds can be started in any containers that are at least 2.5 inches deep. Seed containers should hold the soil well, drain well, and provide space for the roots to grow. One can start seeds in seed starting trays, small yogurt containers, plastic cups, paper or Styrofoam cups, or you can simply recycle your food contains and start seeds in those.
I like to have things organized and keep them simple and hustle-free. Therefore, I like to use seed starting trays with at least 72 cells, and a clear plastic dome to keep the moisture and warmth in while the seeds germinate. I just want to make the planting easy, and avoid thinning and transplanting overcrowded seedlings. I plant each vegetable seed in its seed cell and get individual seedlings rather than planting many seeds in one space and then separating seedlings when planting them outdoors. Once seedlings are ready, I just plug them out and drop them in the garden where I want them. I try to avoid thinning because it is a waste of seeds to me, as I see harvest hidden in each seed. As always, each gardener has his method on how they start their seeds. I like to keep things easy and simple.
What is the best soil for the seeds?
The best soil for seeds is the one that is light and airy, drains water well, holds moisture well, and has nutrients for the sprouted seeds to feed on. To start seeds, use a seed starting mix, compost, or potting mixes.
I do not use seed starting mixes. I like to use a good quality grower’s mix which drains well, holds moisture well, and is airy but most important has already nutrients needed for the young seedlings to grow. When I start seeding outdoors, I might use my compost if I have enough. I avoid mixes that are sterile and have no nutrients for my future seedlings to grow strong and healthy. These add more work for me to do as I would then have to feed my plants. I would have to think of what to feed seedlings with, purchase additional feed, and do the work. You can avoid all these by simply planting in a mix that already has all that and you just water your seedlings while the mix does all the work for you. It is also easy to overfeed or underfeed young seedlings. I simply plant in a good quality mix and don’t have to do anything else besides watering. Do yourself a favor, and give it a try. Start your seedlings in a good quality, nutrient-full mix.
In one of my articles Easy vegetables to start from seed indoors, I share what grower’s mix I use to start my seedlings. So far, I am very happy with it. I use the same mix for my whole Amaryllis collection in growing year-round indoors.
How to sow seeds in the soil
Fill the preferred seed container with your preferred soil. Some choose to moisten the soil before the seed is dropped in. Make a dent in the soil deep as the recommendation on the packaging. In general, seeds should not be planted deeper than twice their width. Drop the seed in, cover it with soil, and tamp the soil. Water well with mist spray or gentle flow. Some seeds like onion, arugula, peas, beets, leek, Swiss chard, lettuce, and radish, can be sown in clumps, or groups. Some need to be sown in individual seed cells or sown in groups but later on, they need to be thinned or transplanted to provide the spacing recommended on the packaging. If you sow seeds in grout outdoors sow them at recommended spacing found on the back of the seed packaging.
What is clump-sowing or multi-sowing
Multi-sowing means sowing seeds in groups, sowing multiple seeds next to each other in a pot, module, or seed tray. Some gardeners multi-sow to save space, to save soil. Some vegetables can be sown in groups of 3-6, but some require spacing. If vegetables that were sown in groups need their spacing, they then need to be thinned or transplanted to accommodate the needed spacing.
Vegetables that can be sowed in clumps
Vegetables that can be sowed and grown in clumps till full maturity are leeks, onions, beets, arugula, peas, turnips, basil, Swiss chard, annual herbs, leafy greens for baby salad, lettuce, radish, arugula, and spinach.
Vegetables that need thinning, vegetables that need to be transplanted if sown in groups
If sowed in groups, these vegetables need to be thinned, transplanted, or divided before planting them outdoors carrots, tomatoes, broccoli, cauliflower, broccoli, peppers, melons, and beans.
How to water seeds
Once the seeds are sowed and covered with soil, water them thoroughly. To water the seeds, they need a gentle mist or very gentle flow to keep them covered and not exposed then potentially left to dry out. Use water mist spray, or a gentle flow to water the seeds. Water them about once a day, and check at least once during the day if they need additional watering or not. Do not let the soil with the seeds dry out, it can delay germination. If the seed starts to sprout and the soil is left to dry, the sprout might have dried out too and you just lost the seed. Soil can be watered from the bottom as well, as long as it keeps the top moist as well. Make sure, however, the seeds do not sit in water as they can rot when overwatered.
I like to water my seeds with a spray water bottle in the morning when my grow lights go on, to keep them hydrated and from drying. Once they sprout and I have little seedlings, I additionally water them with a gentle flow of water to make sure the roots down are watered as well.
It is very easy to overwater seeds and seedlings. Check the bottom of the seed tray and discard any water that sits there.
How to fertilize seedlings
Once the seedlings grow and develop a set of their true leaves, they can be given feed if your soil does not have any fertilizer in it. Young seedlings can be fed a 2-3-1 liquid fertilizer. The numbers represent the value of nitrogen, phosphorus, and potassium.
What light is best for seedlings?
Provide your seedlings with adequate light right after they sprout out of the ground. Intensive light for at least 12 hours or more is best. It should be a bright light, somewhere between 1500-2000 Lumens, and the color temperature somewhere between 4500-6500 Kelvin.
Keep the grow lights closer to the seedlings so they don’t have to reach for light and become leggy. But not as close as to burn them, about 2-4 inches away should be a comfortable distance.
Some home growers choose to use their sunniest window sill to grow seedlings. My beloved mom grew all her seedlings like that. It might work for some, but not for all.
I do not have space on my windows to grow seedlings and have no sunny window that would provide adequate hours of sunlight. I needed grow lights to do the work as my no grow light attempts were not successful.
To learn what grow lights I use to grow my seedlings please visit my article Easy vegetables to start from seed indoors.
How to prepare seedlings for outside planting
Preparing the seedlings for outdoor planting is crucial. Till now they were grown in a controlled, warm environment. Prepare the seedlings to be planned outside by hardening them off, or by acclimatizing them about 1-2 weeks before placing them in their permanent outdoor location. Start to harden the seedlings off by placing them in a shaded location for a couple of hours, then bring them back inside. Slowly increase hours outside by each day, and add time for sunlight. Ensure they are not forgotten outdoors during the night especially during early spring when frosty, frost might kill them.
When and how to plant seedlings outside
Seedlings are ready to be planted outside when they have at least 2 sets of true leaves, are about 2-3 inches tall, the soil is thawed and warmed up, the weather temperatures are right for the seedlings and the seedlings are hardened off.
Allow me to walk you step-by-step in my other detailed article, When and how to plant a seedling.
Reasons for starting seeds indoors
There are many good reasons and benefits to starting seeds indoors. Starting seeds indoors allows you to extend your growing season, allowing those in short-growing season climates to grow long-season vegetables and harvest them in time. The seeds can be started and grow into strong, healthy seedlings long before the last frost date. Once the frost is over you don’t have to start from seeds but already have mature seedlings to grow. You will get to harvest earlier. Starting seeds indoors allows you to grow more by a succession planting method, which gives you more harvest.
I do start seedlings indoors in early spring, and when the weather and the soil outside allow, I also direct seed. Thus, I enjoy succession planting and always have seedlings ready when I pull something out. I also start seedlings outside in a mini greenhouse after the last frost date.
I prefer to grow from seeds, also because it saves me money as I do not have to buy more costly seedlings. I also sell some seedlings if I have too many. I can grow seedlings of some vegetables that are no longer offered at stores as seedlings. I can grow whatever plants I like. And being able to grow from seeds is a life skill for me.
Easy vegetables to start from seed indoors
When and how to plant a seedling