{planning your garden} Guide to Starting Seeds


There are many ways to garden. Some people buy plants from a nursery, your local farmer or garden center, which is a great option for many. I have done this in the past, primarily with annuals flowers (like pansies and petunias), tomatoes and peppers.* Last year, I decided to try my hand at starting my own seeds. Here’s a little how-to for those looking to do the same.

What you need:
Growing Medium
Containers (preferably with a clear glass or plastic cover)
Light and warmth

1. Do some research and math. GASP! Did you actually think gardening required math? Remember your high school calc teacher telling you over and over again that you might actually need this information someday? Well, you don’t need calculus, but you will need some simple math skills. Think about a realistic date when you will be able to plant your seedlings in your garden. Then examine the germination and maturity rates. Some plants (like rosemary) need up to three weeks to germinate; others (like tomatoes) only need about 7 days. Maturity rates are often several weeks. Plus, your seedlings will need to time grow strong enough to survive “in the wild.” Most seedlings will need a five days to a week to “harden off” (ie: get used to the outside weather before being placed in the garden) before they are planted permanently. Work backwards from the date when you want to plant your garden (my rule of thumb is around Memorial Day weekend, when the threat of frost in the Northeast has ended). This means I need to start my seedlings (most of them) around mid-February so that I can have tomatoes come late July or August.

2. Find the best planting solution for your situation. I have two sunporches that retain a lot of heat in the late winter and spring. Pair that with the seed starting kit I use, and it makes for great growing conditions. I selected a tray growing container that nestles into a bottom compartment to drain excess water and circulate air around the roots and includes a clear plastic cover that helps create a warm, humid environment for seedlings (which aids germination). Sounds expensive, doesn’t it. Don’t worry, it only cost me $8, I think. Seed starting takes space, so you will need a shelving unit or flat surface on which to place your seedling trays. You can also use basic pots and planters, but you will want to make sure they can produce humidity. Here’s a trick – cover the top with plastic wrap, and remove/replace for watering. My sunporches generate a decent amount of heat, and I place my trays on the ledge near the windows (see picture below). During the day, I’ll sometimes move them outside to get more light and generate more heat. Seeds love moisture/humidity to germinate, so try to encourage this environment as best possible. Other solutions include greenhouses (small, portable greenhouses are available for purchase at big-box stores and online), on a kitchen windowsill, in cold frames, or under a grow lamp.

My seedling trays

3. Plant your seeds. This is pretty straight-forward. Some seeds require different planting depths, so make sure to read the back of the seed packet for more info. My preferred method of planting is using a good, organic seed-starting mix (NOT gardening soil!). Other methods include peat/soil pellets that come dry (you just insert the seed and add water). These can typically be placed right into the ground once the seedling is ready for transplant. There are also compressed peat moss pots that require soil, but can also be directly planted in the garden when the seedling is ready. Hydroponic plantings are also popular, though I cannot speak to the effectiveness of this method, as I have never tried it. I like the black plastic seedling trays featured in the above picture, as it retains heat in the soil well (probably better than any other method). Add about an inch of soil, then your seeds (for larger plants, add one seed per cell. Most other seeds (tomatoes, peppers, herbs) can be planted two to five seeds per cell. These plants can be divided and planted in larger pots/containers once they germinate and crowding becomes an issue). After seeds are added to the soil, cover with more soil (generally 1/4 – 1/2 inch) and water thoroughly. You’ll need to water every day until seeds germinate.

Also, be sure the seeds you are planting actually want to be seed-started in this manner. Some seeds are direct-sow, meaning you are better off planting them right into the garden. Direct-sow plants include lettuces, kale, spinach (and other leafy greens), radishes, peas, and beans. Basically, any other seeds can be started indoors. Check the back of the seed packet for more specific planting information.

4. Fertilize and Water. Once seeds have germinated, only water once the soil is dry. Too much water/moisture can cause root-rot or mold on the seedlings. The general rule of thumb for fertilization is not to do it until seedlings have developed a second set of leaves (which usually happens 3-4 weeks after germination). Look for a complete organic fertilizer that has trace compounds to ensure seedlings get all necessary nutrients. Seedlings are delicate and cannot handle a full-dose of fertilizer, so dilute the fertilizer to a half-dose with water. Seaweed or kelp extracts and fish emulsions are great for seedlings and help them mature quickly and fruitfully. Again, you will need to dilute these as to not overpower little seedlings.

5. Transplant. Some seedings might get leggy and spindly, which means they are ready to move to a bigger growing environment. Many factors contribute to transplant rates. The back of the seed packet will give you specific information on when to move seedlings to your garden. Transplant factors include the outgrowth of the planting cell or overcrowding (if you plant more than one seed per cell), and garden environment (that is, if the weather is conducive for gardening and the threat of frost is over). If the seedings have outgrown cells, but are not ready for the outdoor garden, simply move into bigger pots or cells.  It is important to acclimate your seedlings to the outdoor environment. Coldframes are great for “hardening off” your seedlings, but cloche pots also work well. Place your seedlings in your coldframe for 5-7 days before planting in the garden. If you don’t have a coldframe, simply place your seeds outside in a sunny spot, being sure to cover with a tarp, blanket or other protective covering at night, for the same amount of time. Be careful to maintain delicate root systems. Use small gardening tools (or old kitchen spoons and forks) to ease the seedling out of its cell.

Please Note!! It’s very important to test your soil before you plant seedlings in your garden for the best success. It’s a really easy step! You can do it yourself at home, or send your soil samples to another source, like Cornell Cooperative Extension and other agricultural education networks. From there, you can amend your soil with calcium (good for tomatoes), nitrogen, phosphorous, and other nutrients.

If you garden using containers, you can plant your seeds directly in your containers, keep inside or in a greenhouse until seeds have germinated, then move the containers outside when seedling are ready. This saves a few steps!

Organic "Beefsteak" and Heirloom "Big Rainbow" Tomato Seedlings
If you have specific questions related to seed starting, please leave a comment or reach out on Twitter (use the #fscgarden hashtag, please!) and I will try to respond as best possible. Good luck!

*If you choose to buy plants to put in containers or your garden, try to buy from a reputable source or local grower. Some studies have shown that the “great tomato blight” of 2009 was caused by a bad batch of plants from big-box gardening stores.

Picture Courtesy of Ms. Christine Hmiel

6 Comments Add yours

  1. Christine says:

    Look at that lush garden of yours! We may have officially given up on our windowsill garden, so I’ll just steal tomatoes and peppers from your plot instead 🙂

  2. emmycooks says:

    Your garden is so beautiful! Mine is tucked into a city back yard so it is a bit less lush and sprawling–but still grows delicious veggies! Thanks for the reminder to start planning for springtime!

  3. @Christine – I’m sure your amazing photography skills make it look all the more lush. Tomatoes, peppers, and whatever else you might like, are totally up for grabs… stop out anytime!

    @emmycooks – GOOD FOR YOU for urban gardening. Seriously, so many people talk about how important it is to do it, but you are putting it into practice! I’m a big advocate for sustainable living, regardless of how/where you live. You are a great example of this! Good luck with your garden and seedlings, I’m always here if you need advice, and thanks for reading!!

  4. narf77 says:

    As penniless student hippies we have learned the value of “from scratch” over and over again and the incredible empowerment of doing things for yourself is a real eye opener. As horticulturalists we have been growing all sorts of edibles (nut trees, fruit trees etc.) to facilitate a 4 acre edible food forest here in Northern Tasmania, Australia. This blog has excited me to more potential and has given me all sorts of ideas. I am mingling organics with permaculture and agroforestry to churn out something customised for our conditions (wet winters and extremely dry summers)…the possibilities are endless, extremely exciting and liberating…cheers for this wonderful post 🙂

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