December 9, 2008

Getting ready for seed starts

A blizzard blew in early yesterday morning, took the power out and froze the ground up hard. Now it is an icy white world with a few inches of snow. My hoophouse project is buried and I'm still awaiting the arrival of the pvc pipe so I'm hoping we don't get much more snow for a few days. The foundation is all set for these ribs and I want to get ready so all I need to do is wing up the plastic in the early spring. I have my potting soil curing ready for the seedling starts that will commence next month. I thought I'd share my recipe for those of you that are looking to make their own. I don't sterilize the soil, as I've never had big problems with damping off, given the right moisture, airflow and microbial balance. I don't want to kill the mycorrhizae and other beneficial microbes. So I like a good compost as the basis of the mix, to provide that community of organisms that keep things healthy. We had a problem with mold in the greenhouse once and solved the problem with a horsetail and chamomile spray. (mix 1/8 cup of dried horsetail, and 1/8 cup chamomile in 1 gallon of boiled water, let steep for a couple hours. strain.)

Here is the recipe for potting soil mix:

2 parts screened, mature (2/3 year old) compost
2 part peat
1/2 - 1 part soil
1 part vermiculite

I pile up these ingredients onto a large plywood sheet in my shed, mix with a shovel, make an indentation in the center and add water into this bowl. When absorbed I mix again and repeat until the soil balls up and crumbles without any water squeezing out. If it doesn't hold together adequately I'll adjust the materials (more compost) until I get it right.

I like a mix with some plasticity as I use a blockmaker rather than flats or plastic for most of my starts. They come in several sizes and the blocks fit into one another in an ingenious way so fine roots are not as disturbed as traditional transplanting. Johnny's Select Seeds carries them. The challenge is in achieving a plastic soil without it being too heavy. I do broadcast some seeds densly in flats and transplant later (parsley for e.g) to save on space under the lights.
For fertility I rely on my good compost and soil, and use kelp, fish bonemeal, foliar fish and have used bloodmeal in the past but have given this up.

I've started my seedling under florescent lights hanging from ropes on tiered shelves... . but I like the idea of this simple design and may set up this system. Its important that air circulation isn't compromised and that the room is warm to maximize quick growth. Once the early starts: onions and leeks are up, healthy and have a few inches of growth, I'll transfer them to the hoophouse to free up space for brassicas, parsley, basil, tomatoes, etc, under the lights. The hoophouse in march and april will keep the killing frost off of the hardier starts and provide warmth for growth when its sunny. I'll start lettuce right in the hoophose.


Patrick said...

We live in different parts of the world, and what works well for me may not be a good option for you, but this is what I use for a light:

A sodium vapor light is about twice as efficient as florescent tubes, so a 400w SV bulb is good for about 800w worth of tubes. However having the light in a single source makes it hard to reflect evenly, so you won't get the benefit of all 800w. Think along the lines of about 600w in practice.

I think one of the main advantages is you just have one pretty small light that can fit on a closet or workbench shelf, instead of dozens of fixtures, bulbs, shelves, chains, wires and other electrical fittings. While there is probably not a big difference in cost, because florescent bulbs and fixtures are not expensive, a growlight is probably a little cheaper for a large setup. A growlight is very bright, so when your plants start using too much space, you can cut corners a bit by raising the light up to cover a larger space and rotate in the plants off the edges which will get a little less light.

The disadvantages are mostly that it's a bit wasteful if you only have a couple of plants, because as soon as you turn the light on you're using 400w. It's also not really practical to make use of vertical space, and generally what you end up doing is putting everything on the floor.

A growlight is also very bright, and I for example have the problem of keeping it from shining into my neighbors houses and bothering them. It also has a very distinctive orange color, and if growing marijuana is not tolerated in your area like it is here, you might attract unwanted attention from the police...

When you think of costs, consider a SV bulb is kind of expensive, about US$50 a shot, and you'll need a new one every 3-4 years.

anne said...

Hi Patrick, I've used florescent fixtures as they they are usually plentiful and cheap at auctions or garage sales...and they fir over shelves well for flats of seedlings. I don't grow single plants under lights and I don't grow marihuana. But I appreciate the inefficiency of florescents. How many lights would you need for 40 flats?

anne said...

ok I reread your light covers 2-3 yards? Thats pretty good.

Patrick said...

I'm not sure how big your flats are, but I think you can compare one 400w SV light to about 20 x 32w florescent light tubes. If you use two florescent bulbs per flat, and have 40 flats, think in terms of 4 x 400w SV lights.

Like I said, in a pinch you can stretch things a little further, because the problem is reflecting the light which comes from a single source. This means it's dimmer around the edges, but very bright in the middle, so you can just do some rotations to make up for this. In the example above, you could probably make due with just 3 SV lights if you wanted.

SV bulbs are bright enough to grow plants to maturity, unlike florescent which are just good enough to get seedlings ready for transplant. Seedlings grown under a SV light are very healthy!

Honestly, if you already have a florescent light setup, I wouldn't throw it all away for SV lights. If you are starting fresh however, SV lights are worth considering.