seed starting in soil blocks

It seems like lately there are tons of posts out there about making soil blocks, and rightfully so, because they are pretty awesome. Hopefully, we can add a bit to the knowledge pool through our own experience trying them out this year.

For those that aren't familiar with the soil block maker,  it's a simple molding tool that creates compressed, self contained blocks of soil complete with dimples on the top to drop seeds in. Ours came from Johnny's Selected Seeds, but there are plenty of places online that carry them.

Soil block maker

Initially, we spent an obscene amount of time reading articles & watching videos on the subject (as we do with most projects ;) before deciding that we wanted to give this a try! Although it is certainly more effort, we're happy we decided to go this route because it provides so many advantages, not just to the plant, but to our pocketbook & the environment as well.  

Some of the reasons we chose to use this method include:

• Elimination of root bound transplants
  The blocks have a bit of open air between them which allows for air pruning. Basically, the roots reach the edge of the block & stop there instead of twisting around and getting root bound. 
• Reduced transplant shock
  Transplanting is much easier on the plant with this method because there's minimal disturbance to the root system, which gives it a running start once it hits the garden.
• Sustainability & Reduced cost
  Eliminates waste & the need to buy pots or other containers. When you're starting a large amount of seeds, as we are, it's more economical than buying countless bags of germination mix and biodegradable pots. 
• Control of your germination mix
  Using soil blocks, you can still choose to use a pre-made germination mix. However, after reading the ingredients of many of the affordable mixes, we found most contain only peat moss & perlite with no added nutrients from compost or fertilizer. We chose to mix our own so the seedlings would have plenty of phosphorus, nitrogen & potassium from the start for fast, healthy growth and higher yield.

Here's a few videos that helped us:

   Front Porch Farm: http://www.youtube.com/watch?v=k2m8-hfhtDU
   SF Urban Farmers: http://www.youtube.com/watch?v=PltQYV1oqec

The recipe we're using for our starter mix came from Front Porch Farms (we divided it in half for smaller batches):

• 5 gallons organic peat moss
• 1/4 cup lime
• 2.5 gallons course perlite
• 2.5 gallons organic compost 
• 2.5 gallons water (add more if needed)
• Fertilizer blend: 2 cups blood meal, 2 cups phosphate, 2 cups green sand

This makes about 4-5 trays with 50 soil blocks per tray, so 200 total of 2"x2" blocks.

Making soil blocks

Ready to fill the trays!

We prefer working with the soil blocks over the peat pellets and small plug flats we used last year. They're easier to move from tray to tray if needed, the dimple for the seed is nicely sized, which makes sowing easier, plus, we can fit more per tray. And they look like little brownies!

We took a cue from Front Porch Farms and also covered our seeds with a bit of vermiculite instead of soil. This helps retain moisture and makes it easy for the little sprout to break through once it's ready to meet the light.

Filling the seed simples with vermiculite

First four trays ready!

Some things we learned along the way:

• Add water to the starter mix gradually
  It took a bit for us to get this right. You want it to be about the texture of oatmeal. A good way to judge is to squeeze a handful of soil - some water should come out, but not a ton.
• Don't try to make the blocks in a wheelbarrow...
  unless you want a serious backache. We found it much easier to move the soil into a small, flat bottomed container & make the blocks at waist height.
• Wear a dust mask when adding the perlite & if possible, buy it in bulk
  Perlite can cause respiratory irritation and is super dusty, so always better to wear a mask. We also try to buy all these components in bulk to save a bit, but the perlite especially gets expensive in smaller bags. If you're in the St. Louis area, OK Hatchery has a ginormous 4 cubic ft. bag for around $20. (compared to $7 for 8oz at Lowe's)
• Use solid bottom seed starting trays
  If you plan to start these indoors under lights, we recommend an enclosed tray instead of the open bottomed ones. We found out the hard way that the blocks dry out pretty quickly under lights & misting isn't sufficient to keep them moist. Plus, with our seed starting system, we don't like the idea of water splashing around 500 watts of light fixtures. Not cool. We've since moved everything over to enclosed trays with DIY capillary mats, which we'll probably be posting details about in the near future.

On a side note, we used Espoma Plant-Tone in place of the fertilizer blend in our first batch of starter mix, thinking, "same difference, right?" It appeared to have the necessary ingredients, but we overlooked it's lower nitrogen percentage compared to blood meal. In theory, this could result in slower plant growth. We'll see soon enough, but so far they're looking great!

Lettuce, spinach, chard & kale - started 2.20

jump starting spring: seed starting station

We've been hyper-focused on getting seeds started this week and making improvements from our slightly sad, leggy seedlings of last year. Our first task this spring was to do some research and decide how we wanted to set up a dedicated seed area. I really have to give Marc the credit on this one. He did many hours of research, went back and forth on what type of bulbs to use several times, and then diligently hunted down all the supplies. He also played a large part in relaying the technical details for this post. He's awesome like that. :)

Last year, we had a modest set up consisting of two folding tables and two shop light fixtures that used Plant & Aquarium bulbs. I think we only did about six trays of seedlings, and it was mostly effective, but not ideal - especially for the amount we're doing this year. In retrospect, we realize now that the legginess of our plants was caused by the fact that the light was positioned a bit too high. We've since found that, ideally, you want the light to be no more than 2"-3" above the seedlings. Each light fixture, under the best conditions, puts out about 6,000 lumens - compared with the midday sun, which measures about 100,000 lumens (!!!) - so really, the more light the better!

We were also total slaves to marketing on the whole "Plant & Aquarium bulb" thing. These types of bulbs tend to be lower in lumen output and heavy in the red spectrum. That's very useful for blooming flowers, but for seedlings, the key seems to be the blue spectrum with high lumen output. Seedlings prefer a cooler light temperature (around 6500k) that promotes fast, stocky growth. Our research also revealed a heated online debate about mixing a warm & cool bulb together to create a wide spectrum vs. just using a full spectrum, high lumen output bulb. After a good deal of consideration, we opted for the latter since it seems to be producing the best results for others.

While we were brainstorming, I showed Marc this nifty set up from Gardener's Supply Company with an equally nifty price tag:

If you can afford it, this looks like it would be a great system to use and seems to have everything you need to get going. However, I'm lucky to have a handy boyfriend who's interested in this as much as I am and who's first reaction was, "$600? Seriously? I can build something like that in a day or two; and for 1/4 the price." Again, awesome like that.

After a picking the features we liked from other set ups and making a few revisions, we decided to build our system using the following:

• 5 tier wire shelf from Lowe's (it needed to be powder-coated to avoid rust & have shelves at least 18" deep to fit our standard 20" seed trays)
• (8) T-8 fluorescent light fixtures (2 fixtures per shelf, 2 bulbs per fixture) We almost went with T-12's but, luckily, found the more energy efficient T-8's for the same price
• (16) Daylight Deluxe 6500k bulbs at 2850 lumen each, so 11,400 lumens per shelf (A variety of manufacturers make these, so you should be able to find them at Home Depot, Lowe's, or similar store.)
• (2) Emergency Space Blankets (the kind you use for camping or emergency kits) We hung one on each side of the shelf unit for light reflectivity and heat retention. These are very effective & also make me feel like I'm in a sci-fi movie every time I check on the seeds. (bonus.) You could also use aluminum foil, or any other reflective material to increase the light.
• (4) inexpensive outdoor thermometers (one for each shelf)
• Power strip with 8 outlets
  

  

  Hanging fixtures

Installing lights

Lights installed & space blanket hung

Completed seed station!

Using this set up, we are able to exceed the lumen output of most of the commercially available seed starting systems out there and for way less money. The whole set up supports 16 trays of starts for approximately $150. We're super excited to fill these shelves in the coming weeks & see how well it works for us!