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Starting From Scratch

Murphy, NC

Hi everyone. I am a new member that has been "lurking" for a while now. PLease allow me to ask a couple newby questions. I would love any/all ideas and suggestions.

I live in zip code 28906 in North Carolina. I am right between zones 6 & 7.
I have just built an unheated greenhouse.

I went overboard and bought many seeds and want to jump in with both feet. I am retired; so time is OK.

Here is my scenario: I have about a 4000 SF garden that I have raised using 2 X 12 lumber. My focus will be primarily vegetables. I will put some flowers around for aesthetics.

Now for questions and plans about starting seeds:

1. I have seed trays, flats and domes that I bought from TEK supply. The flats have slits in the bottom for drainage and watering. When 1st starting inside the house, is this correct: fill flats with soil-less soil; set flats in trays; put about 1/2" water in trays and let soil soak it up; next day, add seeds (as per package and also according to approximate germination times); put dome over flat; put tray under shop light; remove dome when seeds have started to sprout. Keep under shop light.
2. Do I keep water in tray, thus allowing soil to soak up as needed or do I empty the tray of water after about 24 hours?
3. How do I know if soil is moist enough (droplets inside dome)?
4. I know some seeds require darkness to germinate and some require stratification. These will be handled separately.
5. When 1st true set of leaves sprout, transfer to styrofoam cups (16oz) with drainage holes in bottom. How much soil do I put in cups? Allow seeds to grow until able to transplant outside.
6. How will the unheated greenhouse figure in this plan?
7. When do I fertilize seedlings? What kind of fertilizer is best?

PLease help. It seems the more I read, the more confused I get. I will try to get photos of garden and greenhouse soon (it's snowing outside now).

I really respect ya'lls opinions.


Galesburg, IL

Hi Bob and welcome. I'll try to answer some of your questions in the order you asked them. First, I am in Zone 5 and it will be a couple of months before I start any vegetables. I don't know what kind of conditions you will have in your greenhouse, so I'll let others address that issue. For reference, I have a veg garden that is about twice the size of yours, and I also raise a considerable amount of annual / perennial / native flowers each year. Total, I raise between 2000-2500 transplants each year.

1. I use a different method for filling my cell packs and trays. I pre-moisten all soil before I ever start filling trays/packs. I mix water with the seedling mix and then let it sit for about a 1/2 hour to let all moisture be absorbed. As too how wet, you should be grab the moistened mix in your fist and have it form a loose "ball" that won't readily fall apart. You should not be able to squeeze any water out of it with your hand. If you squeeze it and water drips out, add a little more seeding mix and let it sit for a little bit. Not necessarily a scientific/quantitative measure, but it works for me. When I fill trays/cells, I put all the cell packs in the tray and dump the mix on top, and "rub" it into the packs with the flat of my hand. When all are filled, I scrape the excess soil off with my hand. I will then compress each cell with a 35mm plastic film canister (remember those things?) so that the mix is about 1/2 inch below the top edge. I then plant seeds cover and press the cover mix with the film canister again to get seed/soil contact. I then proceed with covering with dome and put under lights. If you have water droplets running off the inside of your dome after about a day under the lights, you have too much moisture and should either prop the dome up to allow for some evaporation, or remove the dome for a while.

2. Do not keep water in the tray after seeding. I will be way too wet and you will kill anything you have sown. I do water from the bottom by adding water to the tray, but I will only leave the water in the tray for about 5 minutes and dump the excess out after that time.

3. It is moist enough if you see a little bit of water vapor condensing on the inside of the cover. Most people keep their seeding mix way too wet and have problems with damping off and other fungi. Seeds need much less moisture than you think to germinate.

4. As needed

5. I don't transfer any of my vegetables into larger containers. I use mostly 804 (32 cells/tray) or 806 (48 cells/tray) cell packs and I leave my tomatoes/peppers/cole crops, and everything else in them until I am ready to transplant. If you are transplanting, wait until the roots start appearing out of the holes in the bottom of the cells before transplanting. With transplanting into larger containers, the goal is to provide more room for the roots to grow. I don't have a set answer for how much soil to put into the cups if you use them, but you probably would want to double the height of the original cells you are transplanting from. Most of the flowers/perennials I grow I start in 128 trays that have small cells and need transplanting much more quickly than the cell packs I use for veggies. When I transplant flowers/perennials, I usually transplant them into a 2.5 square individual pots that are 5 inches tall. They will remain in those until planted outside.

6. Others will hopefully contribute here, I move all my plants outside as soon as possible into cold frames. If you don't have one already, invest in a good HI/Low thermometer with a memory to monitor temps in your greenhouse. As to when to move plants into the house, I would move plants into the house as soon as you can without stressing the plants with temperature extremes. You will also have to be careful not to move small plants into the full sun in the greenhouse without some hardening off. Another thing you will find is that plants need for water will increase unbelievably when you move them into the greenhouse. When I used to work with some research greenhouses many years ago, we needed to water plants at least twice each day. I wish I had a greenhouse to grow in rather than the bank of florescent lights in my basement.

7. I don't start fertilizing until I get 1-2 sets of true leaves emerging/expanding. Many mixes have a small amount of fertilizer in them so you are good until at least then. You want a balanced fertilizer, (10-10-10) is very common and easy to get. It should be a soluble fert and you should only start with about 1/4 - 1/2 strength until the plants get some considerable size on them.

Other info. Many of the flowers I grow (including perennial and natives) I will seed in mass into a 4 or 6" pot and will germinate them and grow them until about 2-4 true leaf stage before transplanting. Annual flowers usually get transplanted into 806 or 1206 (72 cells) and perennials and natives go into the 2.5 square pots.

Finally, you will get much advise here, and no one is wrong in their approach. Everyone differs in what supplies they have available locally, and in their "management style". Glean what you think will work for you and perhaps most importantly, try to keep as good a records as you can about what you are doing and what steps you take as you proceed.

Good Luck, and don't be shy asking followup questions.

Murphy, NC

Thank you sooo much for such a thorough reply. I knew this site was great and you definitely reinforced that.


Elmira, NY(Zone 6a)

1. I don't use domes, but I tend to have a heavy hand watering. I also plant in peat pellets, which are a compressed pellet of peat that expands when they are watered. But I use cellpacks when I run out of those. Peat is probably what the soilless mix you have is made up. When I used to use loose peat, I did like trc65 and wet the soil first. Otherwise, it goes all over. Hot water seems to wet it faster than cold. I also always use a bit of liquid kelp in my seed starting water. Seems to help germination. Keep the seedlings right under the light. I keep mine an inch of less away.
2. I water and then any water left standing after one half hour, I empty out. 24 hours would be risking making the seeds rot.
3. Once you have watered them good, heft the end of the tray. Feel how much it weighs wet. You can look at them for whether they need to be watered, but I lift the end. If it's light, time to water. Don't let it get too light. Once peat dries out, it's hard to wet again.
5. If you already have the styrofoam cups, okay. If not, get yourself a box of 3" or 4" plastic pots, preferably square. You can get cheap ones from greenhouse megastore or harris growers. I have used the same ones over and over for years. The problem with the styrofoam cups is they tip over easily IME. So do plastic cups.
6. An unheated greenhouse is great for hardening off seedlings. I don't have one myself, so I use my covered patio or carport. They can be put outside in a protected area and indirect sun. Work up to as much sun they need, increasing direct sun each day starting with 1/2 hr. But sometimes I get lazy and if they seem strong, just stick them out there. It's a risk. Depends on your temps and stuff.
7. I use only diluted liquid kelp added to watering water as a fert for seedlings. They get a lot of energy from their seed innards. When I put them in the ground, I water them in heavily and then once they are set in good, then I might fertilize if they need it.

Sounds like you've got a WONDERFUL retirement plan! Have fun!

Everett, WA(Zone 8a)

My local nursery throws away pots after one use. I clean them and use them forever.

3", 4", 6", quart, half gallon, gallon and BIG!

I can never seem to break my habit of over-watering, so I'm going to try to make a faster-draining seedling mix. Jiffy Mix (and other brands) seem to hold too much water forever.

This year I'll add some orchid bark (chunky shredded pine bark) and sand. Last year I just added sand, and killed fewer plants than the year before!

I don't know for sure that it really helps, but I took a tip from "Square Yard Gardening" and use a top-layer of vermiculite if I think the seeds will be slow, weak or fussy.
- First I push in a hole twioce as deep as I plan to plant the seed.
- fill that hole with vermiculite (medium or coarse), using a teaspoon.
- Overflowing the hole is fine.
- then push a SECOND hole down into the vermiculite, to the dpeth I wnat the seed(s) to sit.
- add the seed
- brush vermiculite back over the hole to re-fill it, or sprinkle more v. to get the right depth

Vermiculite won't "crust" or dry out easily, and is easy for seeds to push through.

Therefore it would be OK to put the seed a little deeper than you would otherwise, unless they need light to germinate.

Since top-watering would blow the vermiculite around, it reminds me NOT to top-water.
Misting is still an option, but I wish my sprayer had a motion sensor that triggered a recording like "those seeds do NOT need any more water, you dummy!"

I also use the trays of cells or "inserts". I still have 200 Dixie cups of different sizes with slits cut in the bottoms, but they sure do like to fall over!

The "72s" do seem a good size for vegetables and fast-growing plants. I also have a 50-tray of deeper circular cells, but I have to cut that into 1/4s to make it easier to get plants out (my 50-trays, 98s, and 128s are not pre-cut and don't tear apart easily. I can still re-use them after cutting up.)

Can other people get their seedling out of cells without turning trays upside down? I fear I would kill the seedlings if I went digging for them or tugging by the stem.

I turn a few rows of cells upside down or to an angle, and push on the bottom as if it were a plunger to pop them out. A little "shake" helps.

(Do you think getting them out is easier when soil is wetter, or drier?)

I like to keep some air moving with a fan, or at least blow them around 2 or more times times per day to blow gnats away, and strengthen stems.

So far, my seedlings have seldom had enough light, and usually too much water.
And I've often left them in the cells too long before potting up.
I usually sow too many in each cell, then hesitate to thin them out.

But I'm slowly learning!

seed-starting novice

Murphy, NC

Thanks so much. You all really are great.

Calgary, AB(Zone 3a)


Preparing the tray for sowing: I always pre-moisten the soil medium before putting it in the cell trays. Tamp down GENTLY to remove big air pockets and to ensure the soil is right to the bottom of each cell.
Sow to recommended depth, better to be not as deep than too deep
Keep the medium evenly moist, but not saturated. Cover with a dome for germination
Top misting with chammomile tea prevents damping off as well as water. Bottom water about twice a weak and only allow about an hour to uptake the water. Dump the water tray.
Remove bottom heat as soon as the seeds germinate
Remove dome when the seedling have their 1st true sets of leaves
Run a fan once you remove the domes
Start fertilize, diluted to 1/4 strength after the 1st or 2nd set of true leaves
Keep light 2 to 4 inches from the plant material. Put it on a timer for 15 hours. I like them to come on at 6AM and shut off at 9PM
Transplant when you see the roots escaping thru the drain holes. Every transplant will set the growth back by a few days. You indicated that you transplant them into bigger pots when they are quite tiny. Why don't you just start them in the bigger pot/cup.
Make sure all pots etc have drain holes. You don't want to starve the roots of oxygen

The key things are: Maximum Light and no more than 4" above the plant material. Good soil medium that is not compacted. Warmer temperature for germination, cool temperature for growing and yes your light will generate heat, so you may want to shut of the heatpad during the day when the lights are on. Too much & too little water can wipe out your crop. It is very difficult to re-hydrate the medium if you let it dry out too much. A fan will make a big difference in the plant strength and help prevent plant disease.

Unheated GH. Temps need to be above 15C or 60F day and night for most seedlings, but check the seed package

Edit to add: Managing the obsession. You don't have to plant the entire seed package. I often have trays with each row sowed with a different plant species or variety. Very important, label the cells or rows. I like the small plastic tags, which follow the seedling into the garden for the summer, ecspecially if you are doing different varieties of the same species. IE all petunias look the same when they are small.
Hope it helps

This message was edited Jan 12, 2011 9:39 AM

Murphy, NC

Excellent, thanks.

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