Starting From Seed – The Inside Scoop – Seed Starting inside

First of all, not all seeds should be started inside, in fact many seeds prefer being directly planted into the garden where they are to grow for their complete life-cycle. So, before you get too carried away, plan your entire garden and think SMALL! Just like a smorgasbord, beautiful pictures of mature plants, delicious looking vegetables and stunning flowers can lead to garden indigestion if you over indulge. Be realistic on how large an area you will be able to maintain and how much produce you’ll be able to use. No family of 4 needs 12 zucchini plants! There is even a late summer holiday called “Sneak Some Zucchini Onto Your Neighbor’s Porch” day for those that don’t heed that advice. For most families, planting a vegetable garden intensively (think ‘square foot gardening’) provides the most produce in the smallest manageable space. A total of six tomato plants of several different varieties will produce plenty of tomatoes to eat fresh and process for winter.

Which seeds that should be started early and planted outside when the weather is appropriate is based on how many weeks of growing season you have in your area and the temperature of the soil. For southern New England, many gardeners start their onions, tomatoes, peppers, eggplant, basil and perennial flowers early so that the plants have a head start by the time the soil is warm enough to be planted in the ground. Also, first plantings of lettuce, broccoli, and cucumbers are often planted inside a few weeks before they can be planted outside. The shorter your growing season (days between the last spring frost and first fall frost), the more varieties you may want to start inside. Contact your local extension service for more information.

Choosing your seeds.

If you’ve never grown a certain vegetable from seed before, it’s sometimes hard to decide which variety to grow. How do they taste? Are they resistant to diseases? Do they produce a few big fruits or lots of little ones? Are the plants large and rangy or behaved enough for a large pot? Are they hardy enough to produce in my area? Read the descriptions carefully, but if possible, ask a neighbor, fellow gardener or local farmer what varieties they would recommend. The best advice often comes from ‘over the garden gate’. For example, choose 3 different varieties of tomatoes that mature at different times. Remember, you don’t have to plant every seed in a packet (more about that later).

On to the germination station! Preparation is the key.

Plan on starting seeds inside anywhere from 4-16 weeks before you can plant them outside (depending on the varieties). Count back from your average last frost date (for central Connecticut, May 20th or the last full moon in May – whichever is later) to figure the date to start your seeds. As an example, onions are started 16 weeks before frost-free, hot peppers and eggplant 8-12 weeks, tomatoes and basil 6 weeks, lettuce and broccoli 3-4 weeks. Check the list “What to Plant When” as a guide but your local extension service will have better information for your particular area.

A Place to Call Their Own – It’s Important!

Depending on the number of seedlings you want to start, the area can be small, but the seedlings will likely need to be transplanted at least once into larger pots before it is warm enough to plant them outside. The plants from that one 12×18 seed starting tray could end up taking up 5 times the space by the beginning of May. The space will need to have good air circulation, easy access to water, room for lights, possibly a heat mat and be able to stand up to a little ‘mud’. A bright sunny bay window may seem a good choice at first glance, but will your nice white window sills need repainting come June? All seeds need the ‘right’ conditions to germinate, grow and thrive before moving to the garden. Soil temperature, a good medium to grow in, consistent moisture, air movement, food, light and darkness. Some seeds are hard or dormant and may need help to initiate germination (stratification/scarification).


You can be creative by using something as simple as an old egg carton, as involved as an APS (accelerated propagation system) or soil blocks. If it’s your first time starting seeds inside and you’re only planning on starting a few plants, I recommend using one of the seedling starting systems that are completely contained. Most are hard plastic which will last many years of use. They contain a water holding tray or reservoir, a cell tray and have a ‘water wicking’ mat that reduces the number of times you need to remember to water. It’s a small investment for the best possible results. Some even come with a heat mat, a full spectrum grow light and high dome cover if you want that ‘all in one’ system. I’ve also used a ‘soil blocking system’ for many years which involves no containers at all ( No matter what container or system you choose, drainage is absolutely necessary.

A Happy Medium for the Roots to Grow In.

It may be called dirt by some (my UCONN agronomy professor would not be happy if I did), but when growing inside, more often it’s a ‘soil-less’ mix made up of milled sphagnum, peat moss or coir (coconut fiber), vermiculite, with maybe some compost or worm castings. These mixes are free of weeds, diseases, and fungus and have the ability to hold moisture and yet are porous enough to allow air pockets too. Never use garden soil! When garden soil is used in a contained space, it can lead to poor results. You can mix your own medium or purchase one of the many excellent seed-starting mixes that are available. A tip: moisten your mixture BEFORE you put it into the containers or cells. It might seem a little messier, but you won’t have the dry mix push out of the cells when you first water the seeds.

Heat For Their Feet.

Most seeds germinate best at 72-80° or even higher soil temperatures, but prefer cooler air temperatures. The seeds will germinate at lower temperatures, but it can take weeks instead of days if the soil is too cool. Since most households don’t keep the thermostats turned up that high, consider purchasing a seedling heat mat or plan on placing the newly seeded tray on top of something warm. A hot water heater (with the insulation pulled away) or the top of a radiator covered with a towel will do. Even an incandescent light bulb can produce enough warmth to stimulate faster germination. After the seeds germinate, heat is no longer necessary but can encourage faster root growth.

Let There Be Light; and dark too!

Most seeds don’t need light to germinate, but once those green sprouts appear, the young plants need 12-16 hours of direct sunlight every day. You could use a sunny window, but soon you’ll see your plants stretching toward the sun and often in the winter months we don’t even have 12-16 hours of light. Plan on supplementing sunlight with grow lights or use just grow lights on a timer. Full spectrum light bulbs in a standard shop-light fixture will do, or there are many new grow-light systems available now. Read the recommendations for the distance these bulbs should be from the top of your plants as they grow. Traditional grow lights are set 2”-4” above the plants. A few years ago, I switched to T4 bulbs but didn’t realize the intensity of the light that these bulbs produced until one entire tray of seedlings was sun burned beyond saving. A tip: Static electricity will cause dry soil-less mix to cling to the light bulbs, therefore, dust the light bulbs regularly. Plants need dark time too. These green youngsters spend all day turning nutrients, water and sunshine into food to grow. But all their growing is done in the dark.

Facing Into the Wind.

Plants started inside are still prone to some disease problems. Damping Off disease is the most common of them. This presents itself as a perfectly healthy little plant one day and the next day the little stem is bent over at the soil line. If this occurs, there is no saving that plant, but measures are necessary to prevent the spread of the disease to the still healthy seedlings. Remove the diseased plant as soon as you find it. One way to help control this disease is to make sure there is good air circulation around the seedlings at all times. A small oscillating fan works well. This fan also will help prepare your seedlings for their eventual exposure to wind when you move them to the garden. A tip: if you’ve had problems with Damping Off disease in the past, consider top dressing your newly planted seeds with finely milled sphagnum moss.


It’s finally time! You’ve chosen the varieties, found the space and have all your supplies ready.

Set up your supplies in a place that you don’t mind getting a little dirty for planting day.

If you have a self-watering seedling system, fill the reservoir with water, put the wicking mat in place, and the cell tray on the wicking mat. Moisten the soil mix until it’s the texture of a rung-out sponge. You can just add water to the bag and kneed it together. If you don’t use all the soil, it will dry out and still be useable in the future. Fill each seedling cell or container with the moistened medium to the top edge. Press the mix lightly into the cell. Unless you are prepared to sacrifice the extra plants, sow only one seed per cell. I know from experience, that most gardeners cannot bear to cut off the stem of the least hardy baby plant if more than one seed germinates in a cell. This can lead to trying to transplant very tiny seedlings and often damaging the healthiest seedling left behind. If there is no sign of germination within a week in any one cell, then plant an additional seed in that cell. If you are using seed trays (without individual cells), add a few seeds in rows or scattered in the tray. Seeds should be sown approximately twice the depth as they are wide. For some seeds, you can use the tip of a pencil to push the seed gently into the medium. For very small seeds, it’s easier to sprinkle some dry soil mix over the top of them. The seeds will need to have contact with the soil to germinate; this can be achieved by sprinkling water lightly on the top of each cell. I love the old fashion bulb shaped waterer for this. The seeds must stay consistently moist and not be allowed to dry out. Some people like to put a plastic dome over the top of a cell tray to retain the moisture. Another option is to place a white paper towel over the planted seed tray, and water the seeds through the paper towel. The dome should be removed as soon as sprouts appear or the paper towel should be removed as soon as most of the seeds have germinated and are pushing the towel up off the edges of the tray.

Place your trays on the warm area – no need for light until the seedlings appear. Using a heat mat designed for plants will maintain a constant temperature and they are water-proof.

Into the Light.

If the conditions are right, seeds can germinate in 4 days! As soon as you see green growth from 50% of the cells, it’s time to provide the sun. If you wait too long, the stems will start reaching for brighter light. Place the seedlings under grow lights for 12-16 hours per day – use a timer. Now is the best time to provide air movement to prevent damping off disease. You may continue to keep the soil warm to improve root growth (although it is not necessary), but keep the air around the top of the plants cool. Air temperature that is too warm (above 60° at night or above 70° during the day) will also make the stems tall and leggy.

No Wet Feet Please.

Keep the soil moist but not wet. Soggy soil can lead to disease problems and poor root growth. In the beginning, you will not need to water very often. As the plant roots fill in the soil area of each cell, you may need to water every day. If you’re using a self-watering system, just check the reservoir regularly.

Feed Me! Feed Me! Feed Me?

Each seed is a fully contained next generation plant. Until actively growing and the first ‘true leaves’ appear, there is no need to add fertilizer to the seedlings. Once you see these first true leaves, it’s time to start feeding your young plants. Most seedling fertilizers (2-4-2) are water soluble and can be added when you water (or added to the reservoir). A balanced fertilizer (even numbers of N,P & K) or one that is lower in Nitrogen then Phosphorous and Potassium will work fine if that is what you have on hand. Start with one half the recommended dilution. As the plants grow, you may be able to ‘read’ its needs by how it looks (discussed later in Part 3 “Be on the Lookout”).

Pet Me Please!

Everyone laughs at this – petting the tops of your seedlings? You want those wimpy little babies to grow into sturdy, strong plants that produce baskets full of vegetables or arms full of flowers. The stem’s cell wall will not become sturdy until there is an environmental reason to do so. If you touch them, they bounce back and the cells become stronger. Think of it like a weak muscle on your arm; if it is not exercised with resistance – it cannot grow strong. So, go ahead and laugh, then go pet your plants!


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