Starting Your Garden Seeds Indoors
After a long winter there’s nothing more hopeful than pushing seeds into fresh potting mix.
For many years I’ve started my seeds indoors, under lights, before transitioning them to an outdoor unheated hoophouse or directly outside.
Starting your own seeds is beneficial because:
You can control when you plant, thus when you will harvest the crop.
You have access to many more varieties than can be found at the local nurseries.
In the long run, it’s less expensive than buying from the nursery each year.
Growing your own perennials from seed is way less expensive than buying from the nursery.
It’s way more fun!
I want to share with you how easy seed starting can be! You don’t need anything fancy.
I’ll start by outlining what you do need to get started:
Pots and domes
Seeds
Potting mix or growing medium
Lights
Heat mats
Shelves
Now I’ll walk you through each of the above items in more detail.
Pots and Domes
I use 11x21 inch trays and fill them with soil blocks. Interested in soil blocking? Read more HERE!
You can also use 4 pack or 6 pack plastic containers. Or plant straight into 3-4” pots. You can find all these options at your local garden store.
How do you decide which size pot to use?
If you plant into larger containers you won’t have to worry about transplanting later when your plants are getting big. But if you’re growing a lot of plants you’ll get more plants in less space if you use the 4 or 6 packs.
In general, plants I start earlier, I’ll start in smaller pots or packs. Plants I start later or I know grow fast, I’ll start in larger pots. Plants that don’t like root disturbance (like beans, cucumbers, squash, etc) must be started in a larger pot.
Domes are another indoor garden supply you don’t want to go without. Invest in a few plastic domes. These will help keep the humidity perfect for seed germination. Without them, soil may easily dry out or get cold, which is not ideal for germination.
Seeds
Ready to order seeds?
Go to my blog on where to order seeds HERE. It’ll help you get off to a great start.
Potting Mix
There are a few potting mix products that I really like. Most of these mixes can be found at your local garden supply center.
1) Pro-mix MP Mycorrhizae Organik. This is a great all-round potting mix and it’s organic! I’m using this for all my seed starting needs this year. It is also working great for soil blocking! Find this in cubes at Grow Generation.
2) Fishy Peat or Alaska Earth - made in Alaska! I’ve had success with both products. They are not organic but are made with wholesome natural ingredients. Both can be found at Alaska Mill and Feed.
3) Fox Farm Light Warrior or Ocean Forest- this company has a variety of potting mixes and seed starting mixes. They use natural products and they work great! Grow Generation and Alaska Mill and Feed carry these.
If you’re growing a lot of starts, buying a cube of mix will be more cost effective than buying individual bags. Ask your local garden store if they offer these products in cubes!
Lights
I tend to be opportunistic when it comes to lighting. I look for free stuff and cheap stuff. And what’s great is that they’ve all worked great for starting seeds.
So here’s what I’ve used: LED shop lights from Costco, florescent shop lights as found in any hardware store, and grow-specific LED lights. All these will do the job! Buy whatever fits your budget best.
The most important steps when it comes to lighting is:
to keep the lights just a few inches from the plant to prevent “legginess” and
to give your plants 16 hours of light (an inexpensive outlet timer works great for making this happen).
My indoor seed-starting set up.
Heat Mats and Thermostats
For the BEST germination, invest in a a seed starting heat mat AND thermostat made specifically for this. This will cost you around $80.00-$100.00.
If you can’t afford this your first season, don’t sweat! But even soil heat at around 75-80 degrees will give you the best seedling germination (for most plants).
Soil temperatures are roughly 10 degrees cooler than ambient room temperature, so often your soil may be cooler than you think without a heat heat mat. Cold soil leads to slow and poor germination. It can also lead to “damp off”, where your beautiful tiny seedlings suddenly keel over and die. Not fun!
Shelves
I use simple metal wire shelving so I can stack my seedlings. But get creative here! You’ll just need a place to hang the lights and a place underneath to set your trays.
NOW you’re READY TO PLANT!
Fill your pots with damp soil.
Put 1-2 seeds on top. Your seed packet will give you a germination rate for each seed. If its less than 80% put 2 seeds in each pot.
Lightly cover with soil. Just barely cover as light aids the germination of most flower seeds. I like to cover just so there is a bit of soil contact on top of seed.
Cover with a plastic dome and place under lights and on heat mats.
Keep seeds damp but not overwatered. Once seeds germinate I vent the domes by making sure there’s a bit of airflow between the tray and the dome. You can also take the dome off if it’s getting too moist in there.
Happy planting!
Starting Seeds with Soil Blocks
Last year I was inspired to change up my seed starting system to include soil blocking. If you’re not sure what this is, please read on! Soil blocking requires taking a wet grow medium and using a little blocking press to create perfect stand alone squares in which to sow a seed or transplant. I invested in a 3/4” blocker for germinating slow growers and tiny seeds and a 2” blocker for transplanting into or sowing larger or quick growing seeds. These are available from Johnny’s Seeds (my favorite online planting/growing store).
New Methods
A few years ago I was inspired to change up my seed starting system to include soil blocking. I now use it exclusively.
If you’re not sure what soil blocking is, I’ll walk you through the whole process! Soil blocking requires taking a wet growing medium and using a little blocking press to create perfect stand alone squares in which to sow a seed or transplant.
I invested in a 3/4” blocker for germinating slow growers and tiny seeds and a 2” blocker for transplanting into or sowing larger or quick growing seeds. These are available from Johnny’s Seeds (my favorite online planting/growing store).
After lots of experimenting with growing medium (I’ve mixed my own, I’ve purchased all sorts of seed starting mix) I’ve settled on Pro-mix MP Mycorrhizae Organik. I purchase large bales at Southside Garden Supply each spring.
If you’re interested in trying to mix your own starting mix, here’s a recipe from Lisa Mason Ziegler. She’s author of Cool Flowers (a great book about maximizing your cool shoulder seasons for planting early in the spring or late in the fall - I’m still trying to perfect this method in a snowy climate, and honestly still sort of flailing):
Recipe
16 C sifted peat or coco fiber (I used our local Fishy Peat mix available at Mill and Feed)
4 C of sifted compost (I used Susitna Organics humidified compost)
1/4 C greensand (available at Southside Garden Supply - let me put a plug in for this awesome local shop. Thanks to the marijuana industry, this place is loaded with great stuff for the urban farm or garden set-up)
1/4 rock phosphate (Mill and Feed or Southside Garden Supply)
6-7 C water
How To
Mix all ingredients well in a large tote or bin. One batch makes around 600 mini blocks.
If you’re using Pro-mix MP Mycorrhizae Organik or another pre-made mix, just mix a set amount of soil in a tub and add water until it’s a very wet mud.
Once your planting medium is all mixed grab your blocker, dip in a dish of water (aids in releasing blocks), firmly press your blocker down into soil medium a few times to really pack it in, scrape off excess, and while holding just above the bottom of your seeding tray depress the plunger until blocks release.
It takes a few tries to get the hang of it! Seeds can then be planted in the little depression left my the blocking pin.
Get creative about what you use for trays. I use regular seedling tray bottoms with no holes. I reuse these every year for 3-5 years! Folks also use lunch trays, plates, left over styrafoam trays, yogurt lids, etc.
Growing on
To water, less is more. Although you don’t want to desiccate your precious seedlings it’s easy to over water and get disastrous results (like damping off). Be sure to water from the bottom to preserve the delicate soil block structure. They wick up water like crazy.
Once the 3/4” blocks are ready to transplant, plant directly outdoors or up-pot into a 2” or 4” block. I up-block into a 2” block for most of my starts.
The larger seed blockers come with a different blocking pin that creates a square indent that perfectly fits a 3/4” block.
Now go grow some epic plants!