Starting from seed; everything you need to know in 10 easy steps
If you live in the Northeast, you know it’s been one heck of a haul towards something remotely resembling spring these days. With mornings still hovering in the 30's and 40's and afternoons barely scraping the 50 degree mark, it’s hard to make a case for any early spring planting in the garden. However, for those of you who read my last post about keeping busy while it’s still cold outside, you’ll know there’s nothing idle about these winter-esque days. With nearly four weeks until Mother's Day (the unofficial green light day for planting in the garden) , now’s still a great time to get your seeds started indoors if you haven’t already!
TO NOTE: In this post, we'll only be exploring starting seeds indoors, versus directly in the garden.
Before you begin, you’ll need a few essentials:
Any seeds you plan to grow this season
Obviously, seeds are the foundation of this exercise, and by now you should have a general idea of what you plan to grow in your garden. As I mentioned in my last post, there are multitudes of options to consider, and be careful not to buy more seed than you need!
A few of my favorite suppliers for organic seed are Hudson Valley Seed Co., Seed Savers Exchange, Territorial Seed Co., and Johnny’s Select Seeds. These companies offer everything from heirloom seeds to disease resistant varieties, so read the descriptions carefully and select the best types for your space and personal needs. And, if it’s a flower garden you’re after, definitely check out Floret Flower Farm for a dreamy selection of cut varieties!
Planting trays, seed starting kits, and/or small pots
Equally as important as the seeds themselves, make sure you have something to sow them in! If you’re trying seeds for the first time, there are many inexpensive and efficient seed starting kits available that come equipped with everything you need to start your seeds from home. Jiffy Greenhouse seed starting trays are a great option for small spaces!
If you’re a bit more thrifty, you can re-use old flower flats or small plastic pots from last season. Egg cartons are great, too! Just be sure to thoroughly wash them before hand in case there’s any pathogens lingering that may jeopardize the health of your seedlings.
Sterile seed starting mix
This is probably one of the most overlooked yet most important aspects of starting your plants from seed, and one which I cannot stress enough. Regular potting soil often contains pathogens and even certain pests that may harm your fragile seedlings and inhibit their growth.
By comparison, seed starting mix is a sterile formula that has been heat-treated to kill any lingering disease in the soil and give your seeds the best chance at survival. You can find seed starting mix online or at most major home improvement stores and garden centers; it’s definitely worth the investment!
These can be store bought plastic gardening labels, wooden popsicle sticks, or even strips of cardboard cut to size – anything that allows you to keep track of what varieties you’ve planted where, and on what date. Noting the date can help you keep track of germination rates and fertilizing schedules, and key you off to any health issues if plants aren’t germinating within the range noted on the seed packets.
If you opt to be thrifty and re-use old flower flats or other small plastic potting trays, you’ll want to cover your seeds with a layer of plastic wrap prior to germination so that they retain moisture and heat. Think of it as creating your own temporary mini greenhouse for your seedlings!
Right after you plant your seeds, and while the seedlings are still very small, you never want to water heavily from above, as you may run the risk of disturbing or washing away your seedlings before they’ve had a chance to establish their roots.
Bottom water from a tray to start, and then use a spray bottle to apply a fine mist. This will allow you control the amount of moisture you introduce, and keep the seedlings from being jostled around too much.
Sharpie or pen – for labeling your seeds and taking notes!
In addition to the basics above, you may want to consider the following optional but highly recommended items:
Vermiculite can be found in store bought potting soil mixes, or purchased by itself, and is a mica-like mineral that prevents damping off, a common fungus that can afflict many infant plants. Fine grade vermiculite is light weight, inexpensive, and when applied to the surface of your soil post seed-sowing, will prevent mold from killing your precious seedlings.
In addition to moisture, seeds require warm soil temperatures to germinate. Heat mats are easy to use and guarantee an even source of reliable heat if placed beneath your seed starting trays from the get-go.
Grow lights are definitely not necessary for the beginner trying his or her hand at seed propagation for the first time; however, if you lack sufficient sunny window sill space, and/or live somewhere where it’s just too cold to risk keeping your seeds outdoors, there are a number of garden retailers that sell reasonably priced small-space models that can allow you to set up shop in the comfort of your own home. Or you can build your own! Some of my favorites include Gardener’s Supply Co., and Burpee.
Once you have everything you need, find a bright, clean work space and let’s get started!
1. First you’ll want to prep your seed starting mix so that it’s moist, but not dripping wet – typically the consistency of a well-wrung out kitchen sponge.
Wetting the soil before planting is critical because seeds require a moist environment and need to be in close contact with the soil in order to germinate. I use plastic bin to wet and mix my soil to keep everything contained and avoid making a bigger mess than necessary (sometimes easier said than done!).
2. Next, using a garden trowel or kitchen spoon, fill your trays or pots to the top with the moist, sterile seed starting mix. Once full, use your thumbs to firmly press down along the edges and then gently tamp down the middle so that the surface is even.
Compressing the edges will keep the soil from contracting when dry and increase moisture retention as your seedlings emerge and begin to grow.
3. Now you’re at the exciting part – sowing your seeds! However, before you fully dive in, review any instructions on the individual packets for seed depth recommendations and germination times. If you can, try to group seeds that take about the same amount of time to germinate in the same tray so that you’re not stuck with runaway tomato seedlings while your strawberries are just starting to pop up!
The New Seed-Starters Handbook by Nancy Bubel and Jean Nick is a fabulous resource and one which I personally find to be invaluable when I’m starting my garden from seed. Besides noting in detail which seeds should be started indoors versus directly sown in the garden, it’s full of tips and tricks for getting the most out of your vegetable, flower and herb seedlings. I’ve said it before, but it really is the equivalent of life hacks for your garden!
TO NOTE: Now that you’re ready to sow your seeds, remember that seed depth is important. Seeds come in many different shapes and sizes, and this influences how deeply they should be planted in the soil.*
* As a quick botany lesson: all seeds contain within them a built in energy source which includes an embryo and cotyledon. The embryo supplies the plant with the sugars and nutrients it needs to reach the surface and begin to grow before it is able to produce its own food via photosynthesis, and the cotyledon becomes the plants first leaves. Plant too deep, and your poor seedlings will use up all their energy and the cotyledon will die before it’s able to reach the surface. Yikes! *
4. Now, using a pen or pencil, make two to three evenly spaced, shallow holes per tray cell or pot in your soil. Place one seed in each hole and cover with soil. Make sure to press down lightly afterwards to ensure the seeds are in contact with the soil. Think of it as tucking your seeds in!
For extremely small seeds such as strawberries or basil, sow your seeds directly on top and then lightly press down to ensure contact. Personally, for small seeds like these that are hard to handle, I gently tap the seed packet a few times to lightly and evenly sprinkle them along the surface.
5. Label each cell in your planting tray or individual pot with the plant variety and the date.
6. Next, sprinkle a light layer of fine-grade horticultural vermiculite on the surface of your soil. As noted above, this will help prevent damping off, a common fungal disease that can devastate your seedlings.
7. Fill your spray bottle with room temperature water and mist each tray cell or individual pot several times so that it is thoroughly moist. Make sure the water is room temperature and not cold, otherwise you may inadvertently send your seedlings into shock! Remember – seeds germinate better in warmer soil temperatures, so keeping conditions stable will be best in the long run.
8. Finally, if you’re using a seed starting kit, cover your tray with the plastic cover and place in a warm, sunny window. If you’re re-using old flower flats and pots, cover with clear plastic wrap and make sure it’s secured around the edges to lock in heat and moisture.
Additionally, if you invest in a heat mat, place your finished trays/pots on top of the mat. As soon as your first seedlings begin to appear, remove the plastic cover/wrap and heat mat. Failure to do so invites mold that will kill your seeds, and may cause your seedlings to bolt before they are ready to be transplanted.
9. In two weeks, apply a half-strength liquid fertilizer to your seedlings to provide additional nutrients while they continue to grow. I recommend a seaweed emulsion, which provides equal parts of the three essential elements for plant growth, Nitrogen, Potassium (also called Potash), and Phosphorous.
10. When seedlings are at least two inches tall and/or have their first set of true leaves, they are ready to be thinned into bigger pots! To do so, carefully remove each seedling from its individual tray or pot and gently separate the individual roots, being careful not to rip or tear. Use regular potting soil (moistened in the same way we did for the seed starting mix), and place each individual seedling in its own pot.
Sprinkle a light layer of fine-grade horticultural vermiculite on the surface and mist with room temperature water. Place thinned seedlings in a sunny window or under grow lights until they are ready to be hardened off and eventually planted in the garden.
And voila, there you have it – a ten-step guide to getting those seeds started and ready for the great outdoors!
I’d love to hear from you; what kind of seeds are you planning to sow this season? Have you already started and need guidance on where to turn next? Leave me a comment, or visit my Contact page and send me a message!
As always, happy planting!