There are advantages and disadvantages to each system.  For small quantities of say less than 100 plants, the jiffy pellets work fairly well.  Remember to cut the netting off the pellets before transplanting to larger pots.  The jiffy pots dry out quickly and they don’t break down very easily in the garden so if using the pots, be sure to cut the sides or remove the pot before planting outside.  The best tip on using the jiffy pots is to place them in an aquarium which can easily be set outside on sunny days and brought indoors in inclement weather.  Put a piece of glass or plexiglass on top of the aquarium and prop it up for air circulation to prevent rain damage.  Pour water into the bottom of the aquarium and it will wick up into the plants.

If growing seedlings in volume, seed trays are the best option.  Start seed in dedicated seed trays with per seed spacing of about ½ inch.  Up to 1000 seedlings can be grown in an 11” by 22” tray using this method.  If you want to start several varieties, use a 48 or 72 cell flat and plant up to 25 seed in each cell.  Carefully label the cells and when the seedlings have their first true leaves, transplant to individual cells in seed trays again carefully labelling the seedlings as you go.  Here is a summary of the steps in growing seedlings:

1. Use the best seed starting mix you can get.  Not potting soil, not topsoil, only the best soilless seed starting mix.
2. Start the seed about 5 to 8 weeks before you plan to transplant outdoors.
3. Thoroughly moisten the seed start mix and place it in a tray.
4. Plant seed in the mix and cover with a plastic bag with the end propped open for a little air circulation.
5. Place the tray in a warm spot such as on top of the TV, Refrigerator, etc. or use a heating mat to get 70-85 degrees F.
6. The minute you see the first seedlings germinating, remove the bag and place the tray under grow lights for 16 hours/day.
7. Keep the temperature between 50 and 70 degrees while the seedlings are growing.  55 to 60 is the best.
8. When the first true leaves on the seedlings are about 1/2 inch long, transplant them to individual cells or pots.
9. Bury them up nearly to the true leaves so the stem can root, then place back under grow lights and let them develop.
10. Water the seedlings only when they are dry but avoid letting the plants wilt.  Fertilize only if you prefer to do so.
11. I choose to apply 2 feedings of 1 level teaspoon of 15-30-15 to a gallon of water and using that gallon on about 150 plants.
12. Transplant outdoors when the seedlings are about 8 to 10 inches tall.

How do you prepare seed trays in volume?

I use a 3.8 cubic foot bale of miracle grow seed start mix (or equivalent). I start by cutting open the top of the bale and digging a bowl shaped depression into the top of the tightly compressed mix. I then pour in a gallon of water and mix thoroughly by hand. My seed flats are sitting beside me so I place one on a piece of plastic and quickly transfer a scoop of the mix onto the tray. I spread the mix into the cells and pack it lightly with my fingers to the desired depth which for me is about 1/2 to 2/3 full.  I fill as many trays as the moistened mix allows, then pour another gallon of water into the bag of mix and repeat the process.

Seedlings are popping up everywhere, when do I feed them and what do I use?

It depends on the seed starting mix you used.  Some mixes are pre-fertilized with enough nutrients to take a tomato plant to the 4 leaf stage.  Other mixes do not contain any extra nutrients.  A very few contain inadequate nutrients to grow seedlings and may require supplements before the first leaf emerges.  A general suggestion is to watch carefully the growth of the seedlings and if they are not growing at a reasonable rate, then consider feeding them.  You can water with a liquid mix of 15-30-15 at a rate of 1 level teaspoon in a gallon of water or you can make manure tea to water them with.

How do I make manure tea?

A simple method is to put ½ gallon of composted cow manure in one leg of an old pair of pantyhose.  Tie a knot in the top and drop it into a 5 gallon bucket nearly full of water.  Let it steep for a week and then stir well before using it to water plants with.  Another useful method is to bore a small hole in the bottom edge of a plastic garbage can.  Sit the can on top of some cinder blocks and fill it with composted manure.  Pour water into the top and manure tea will drip out of the hole in the bottom.  If the manure is really dry, several gallons of water may be required to get it to start dripping.

What about using coco fiber (coir)?

Its often reported as a good seed starting medium and is more renewable than peat.  Hydroponics suppliers may be the best source.   Advantages over peat are: easier to wet, neutral pH, and contains a modicum of nutrients.  There's some debate over whether the ecological argument that peat is a non-renewable resource is valid. Northern areas act as "carbon sinks" while tropical areas don't store carbon, so (the counterargument goes) the coir is taking carbon from where it's needed most, while peat is returning it to circulation.  Pay particular attention to nutrients when using coir.  It may not support normal seedling growth without amendments.

What is a good light system to use for tomatoes?

A fairly cheap setup is a couple of fluorescent shop lights on a stand.  You can build one or buy something workable at several of the large home building materials stores.  Use one warm white and one intense cool white bulb per fixture to deliver a fairly balanced spectrum.  The bulbs should be kept about 2 inches above the top of the plants.  High intensity lights such as halide and high pressure sodium should be used if plants larger than 10 inches tall are desired.  Use only bulbs designed for plants if you choose one of these systems.  One problem with the HID systems is that they provide point source light which can cause seedlings to grow taller due to shading effects.  A good track system that moves or rotates the light avoids this problem.

Some of my seedlings are taller than others, what do I do?

Presuming you are growing them under lights, you can raise the lights above the tallest seedlings then sit the shorter plants on boxes or anything that will raise them up to a similar height with the taller plants.

Can I grow seedlings in my Basement? Garage? Outbuilding?

Yes, as long as the temperature is in the correct range.  One person had a problem with seedlings being eaten by mice.

What temperature should seedlings be grown at?

There is a minimum temp for seedlings but it is highly dependent on the variety in question. Generally, seedlings should not go below 45 degrees fahrenheit. They can stand temps a bit lower but they almost stop growing until the temp is a bit warmer.  Tomatoes grow best between 50 and 75 degrees. Greenhouse growers generally try to propagate seedlings with germination over 70 degrees but with daily growing conditions around 60 degrees.  If the growing temperature is too high, the seedlings get “leggy” and have poor physical structure.

Help! My seedlings are turning purple, what do I do?

This is usually a result of some combination of cool temperatures, low phosphorus or micronutrients, and too much light.  Some varieties seem to do this normally. It usually appears on the seed leaves, not so much on the true leaves. Eventually the plants grow out of it.  The best solution is to use a good micronutrient supplement with extra phosphorus to water with. You can also toss a handful of rusty nails in a jug of water and use it to water the seedlings. They seem to like the extra iron. Consider also the water source you are using. If it is clorinated or has an excess of salt, it can build up in the pots and cause serious problems. You could try flushing the pots by deliberately overwatering till it leaches the contaminants from the soil. Immediately follow up with a nutrient supplement if you do this as it will also leach most of the nitrogen from the soil.  You might also consider spraying with seaweed emulsion.  If you are keeping the plants under 24 hour lights, turn them off for 8 hours per day.  For growing in a greenhouse, see What effect do gases such as ozone, ethylene, and natural gas have on tomatoes?

How do I germinate seed?

Moisten a paper towel, wring it out, then spread it open.  Place seed on the towel and roll it up very loosely.  Place the towel in a ziploc type bag and place in a warm spot such as on top of the refrigerator for 2 or 3 days.  Check for germination.  Some people use this method to get germinated seed to plant.  This allows them to have 100% seedling emergence in the growing media.  It works but handling the damp seed is time consuming.

How fast should my seed germinate?

It depends mostly on the temperature, humidity, and the age of the seed.  Below 65 degrees, germination is seriously delayed and at 50 degrees virtually stops.  Older seed also tend to take longer to germinate than fresh seed.  Generally, good seed will germinate within 4 to 7 days and older seed within 20 days.  There are a very few varieties that take up to a month to germinate and thats just the way they are.  There is one species closely related to tomato that normally has to go through a tortoises gut before it will germinate!

My seedlings are 5 weeks old and growing healthy but oh so slow?

This can be a sign of inadequate nutrients in the potting mix, too low temperatures, or improper light level.  Make sure the temps range from 50 to 75 degrees Fahrenheit and that the lights are on at least 14 to 16 hours per day.  Once that requirement has been met, consider feeding them with manure tea or a fertilizer concentrate.  Miracle grow 15-30-15 can be used at a rate of 1 level teaspoon in a gallon of water to water about 150 seedlings.  This is a low enough concentration to avoid burning the roots.  Some other fertilizers contain micronutrients which can be very beneficial for tomatoes.

How do I thin out my seedlings?

You could try to 'prick out' the smaller seedlings and transplant them to other jiffy pots or into small pots as individual plants.  Do this with a knife or a fork with only one or two tines.  This method is especially good if you have limited numbers of germinated plants for a given variety and can't afford to waste plants. If however, you do not feel confident doing this better then to thin to the strongest seedling in each pot.  You can cut off the unwanted seedlings at the soil line with a small pair of scissors leaving only the strongest and best looking plant.

How can I improve germination of old or poor quality seed?

There are several methods that improve germination of poor quality seed.  Imbibing is the proces of encouraging the seed to take up water.  This can be achieved by dampening a paper towel and then wringing it out so it is moist but not soggy.  Place a few seed on the spread out towel and roll them up.  Place the towel in a ziploc bag in the refrigerator overnight.  Label the bag if you are doing several varieties.  About 16 hours later, get the seed out of the bag and plant them in a tray of well prepared moist seed starting mix.  Controlled temperatures will help at this point.  Either use a heat mat under the seed tray or use an incubator to regulate the heat to about 85 degrees Fahrenheit.  Watch the seed mix and if it starts to dry out, either water or use a spray bottle to mist the surface.  Germination of old seed may take 3 to 5 weeks so be patient.  When the first seedling appears, get the tray under light.

What about a seedling heating mat?

An el cheapo heating pad from Wal-Mart works just as well as an outrageously expensive seedling heating mat.  Use a probe type thermometer (available at Wal-Mart for under $20) to check the temperature and cover it with  a piece of plastic to keep from accidentally getting it wet..  Another good heating pad is a waterbed heater.  If you are really growing a LOT of seedlings, consider using an electric blanket.  Spread it over a large table, cover with a plastic sheet, sit trays on top, and adjust the temperature to about 72 degrees fahrenheit.

Where can I get heirloom seedlings?

There are several online sources but be prepared to pay a stiff price.  By the time you have spent lots of time and effort and some real cash on getting set up to grow your own seedlings, they may still seem cheap.  Some local garden suppliers have heirlooms as well as hybrids.  Check out forums such as gardenweb.com to see where they may be locally available.  There are some good local producers scattered across the U.S.A.

I grew seed of variety X and they are imposters!  What do I do with these seedlings?

This is happening more and more often these days.  Seed are being substituted for the real variety or crossed seed are being shipped.  It helps if you know someone else who has grown them and can find out if the tomato is worth growing.  There is a potato leaf faux Red Brandywine and a yellow that is being called Lillian’s but is not.  The potato leaf Red Brandywine is reported to be an excellent tomato and at least one good report is on the net about the faux Lillian.  I personally don’t want the imposters, I bought seed of a specific variety and if its not that variety, then I want the real thing.  You might consider giving the seedlings to someone who would like to give them a try.

What kind of potting soil should I use to start my tomato seed?

The best light textured soilless seed start mix you can find.  Peters, Promix, and Miracle Grow all produce excellent mixes that are approximately equal parts peat, perlite, and vermiculite with a bit of lime to adjust PH.  It is best to avoid garden soil, potting soil, topsoil, etc. either because they carry diseases that may kill the seedlings or because they are too heavy a mix for good seedling growth.

Whats the best way to water my seedlings?

Almost any way except pouring water onto the seedlings.  If they are in seed flats, put water in the bottom tray and let it wick up into the cells.  You can also use a spray bottle to mist water onto the plants.  A squeeze bulb, turkey baster, even a large syringe can be used though not as conveniently.  In greenhouses, a sprayer is used to spray water onto the tomatoes till the soil is saturated.  One very big warning, overwatering kills more seedlings than just about anything else.  Let them dry out till the potting mix is dry and crumbly and the plants are about to wilt, then water thoroughly.

The seedcoat is clinging tightly to the cotyledons, what do I do?

Sticktight seedcoats occur on a large number of seedlings.  In most cases, they are easily removed.  Start by moistening the seedcoat.  You can mist it with water, hold a soaking wet cotton ball to it, or just drop water on it from your fingers.  One person even recommends putting a small ball of saliva on the seedcoat to soften it.  Once it is thoroughly soft, you should be able to gently pinch it free or use a needle to release it or even just leave it be and let the plant push it off.

An excellent method to reduce the number of sticktights is to soak the seed pre-plant for 30 minutes in a solution of household bleach and water at a ratio of 1 part bleach to 5 parts water.  The disadvantage of doing this is that you have to handle wet seed when planting.  It does reduce sticktights and can help reduce seedborne diseases!

I started my seed, now they are 3 inches tall and falling over, what did I do wrong and how do I fix it?

You probably didn’t give them enough light fast enough.  Seedlings should be under at least 12 hours per day of light from the very first day they start to emerge and the light source should be less than 4 inches above the seedlings.  At this point, they might be salvaged by transplanting to deep seedling flats or pots so that the seed leaves are an inch or less above the soil line.  You will have to be very careful, “leggy” seedlings are very easy to break.  Tomatoes have type C3 chlorophyll and they saturate at light levels around 400 mols.  Direct sunlight is about 2000 mols.  A light source that provides about 500 mols will do an excellent job.

Threee cotyledon leaves, Is that unusual? (its not a missprint(>:-)>

No, its really quite common with some varieties more likely than others.  The plants are usually normal and the 3 cotyledon leaves just drop off like normal 2 cotyledon plants.  Another common malformation is 1 or 2 cotyledon leaves with  no growing point.  Eventually this type plant dies because it cannot produce any new leaves.

Do you “harden off” tomatoes by pouring concrete in them?

Hardly! (pun intended)  You harden off tomato seedlings by gradually acclimating them to weather conditions outdoors.  When grown indoors, seedlings do not develop the ability to handle temperature extremes or direct sunlight.  Place them outdoors in partial shade for an hour or two the first day, 3 to 6 hours the second, and all day the third.  By the fourth day, they should be able to handle direct sunlight for a few hours.  It takes 7 days to harden off most varieties.

What about direct seeding in the garden?

Growers in areas that don't have a cold season can grow tomatoes year round or at least more months than in colder zones. Tomatoes are a perennial, originally from the tropics, so if temperatures never get below about 40 F they could conceivably be kept year round, pruned, treated etc.  Also, if you are in an area with a long enough season, you can direct seed tomatoes to be transplanted for a fall crop.

Alas, the pen I used to mark paper pots faded.  How do I “permanently” label tomatoes?

There are special plant marking pens and "paint" pens that will not fade.  Don't be fooled by the permanent markers such as Sharpies.  They will fade in sunlight in about 6 weeks.  If its really important that permanent labels be used, you can cut aluminum pie plates into strips 3 inches long by one half inch wide and use any sharp pointed object to inscribe a name into the metal.  Either bend it around a branch or place it on a stake near the plant.

When do I transplant my seedlings, I am in zone X?

Seedlings should usually be transplanted after the last frost date for your area.  Contact your local agricultural extension office if you don't know what that date is.  Some general ranges are: zone 9 February to early March, zone 8 March to early April, zone 7 late march to mid April, zone 6  mid to late April, zone 5 mid May.  These are not absolutes and there will be years when tomatoes could be planted earlier and other years when cold temperatures will last longer than normal.

What on earth is a “leggy” seedling and what do I do with one?

A leggy seedling is one with a root system, a loooong stem, and a few leaves near the top.  It is a result of growing in competition for light or with inadequate light.  If your seedlings get “leggy”, you may be able to salvage them by re-potting in deep pots so that you can bury several inches of the stem.  When you get ready to transplant outdoors, make a trench to plant them.  Lay the stem out in the trench and prop the leaves up above the soil so they can grow.  The plants will root all along the stem which makes the plant more productive.
 

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