There are several methods depending on the resources you have to care for the seedlings. How big do you want your plants to be when transplanted? If you start seed 5 to 8 weeks before transplanting, your seedlings can grow in seed flats and will be about 10 inches tall at transplanting. If you start 8 to 12 weeks early, then plan on growing them in pots up to 12 inches diameter. Find out your last frost date by calling your co-operative extension agent. Plan on transplanting within 2 weeks after that date.
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 sterile soil-less 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 covering them 1/8 of an inch deep with seed start 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.
11. Either brush your hands across the plants twice a day or else get a small fan that will blow air across the plants to enourage stocky stems.
12. Fertilize only if you prefer to do so. 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.
13. Transplant outdoors when the seedlings are about 8 to 10 inches tall.
14. Check on the plants often in the first 2 weeks after transplanting. This is the time that most problems can occur.
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.
What kind of grow mix should I use? Is potting soil ok? What about using coco fiber (coir)?
This is arguably the most important decision you will make for growing healthy seedlings. You should ONLY use seed start mix made specifically for that purpose and that has been STERILIZED. Promix BX or MPX, Miracle Grow, Peters, Fafards, etc all make good seed start mixes. Do NOT use garden soil! Do NOT use potting soil! Do NOT use the remnants of that bale of damp seed start mix you saved from last year! Why is this so important? Tomato and pepper seed can be totally killed before the seed germinates by fungi that live in un-sterile soils. If you use garden soil or potting soil, then it will contain phytothora and other organisms that are only too happy to feed on your seed. Picture little green eyed big mouthed monsters screaming "MEAT!" when your nice fat seed show up for dinner. If you store damp seed start mix over winter, the fungi in the air will multiply which means it is no longer sterile and now has a healty population of seed munchers. Use stored seed start mix ONLY if it has been stored dry.
Peat moss is a good beginning for starting seed, but it is not appropriate in pure form. Mix it with vermiculite and/or perlite and then add some lime to balance the ph. There are several good recipes available on the net. Please note that if you mix your own seed start mix, you must add nutrients! Most of the commercial mixes are prepared with a small amout of NPK plus micronutrients.
Coir is 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. Most of the coir on the market does not contain enough nutrients to grow seedlings. You must be prepared to fertilize them to get normal growth.
Can I "mix my own" seed start mix?
You certainly can, however, be aware that most organic materials like compost, worm castings, topsoil, and manure are heavily infested with fungi that just love to munch on tomato seedlings. If you mix your own, be prepared to sterilize the soil mix. This can be done by putting an inch of water in the bottom of a large pan, bring it to a boil, pour in the seed start mix, cover with a lid, then bring it back to a low boil for 20 to 30 minutes so steam and heat sterilize the mix.
A good formula for homemade seed start mix is 2 parts worm castings, 2 parts peat moss, and 1 part perlite. This mix is light enough for most seedlings but has enough nutrients to last about 3 weeks from germination. Don't forget to sterilize it, the worm castings are nice for older plants but are full of fungi that devastate seedlings!
I did what you said, I planted the seed, NOTHING is growing?
If viable seed were planted to begin with and if the seed start mix is properly moist and you waited an appropriate time (4 to 21 days for tomato) but nothing has germinated, then you may have a problem with evaporative cooling. Evaporative cooling can do enormous damage to seed because it keeps the surface of seed start mix up to 15 degrees cooler than the ambient temperature. The containers you use to germinate seed must either be in a very warm location where humidity is balanced or they must be covered to prevent evaporation. If your seed trays were properly prepared with the right amount of water and the seed are planted at the right depth but you place them on top of the refrigerator in a cool room, the seed may take forever to germinate because evaporation at the surface of the soil is reducing the temperature from a comfortable 72 degrees down to a frigid 58 degrees. There are two ways to prevent this. Put the seed trays on seed start heat mats and/or cover the containers with clear plastic. Either way, monitor for germination at least twice daily and move the trays under lights immediately when seedlings appear. Please note that the clear plastic dome covers sold with many seed start trays will provide the proper protection from evaporative cooling, but they should NEVER be left on the tray in full sunlight. Heat will accumulate inside the dome and can reach temperatures of 180 degrees which will make crispy critters of your seedlings.
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. Please note that very small amounts of fertilizer are needed, 1/2 teaspoon of 15-30-15 is enough to grow 48 seedlings to 8 inches tall.
How fast should my seedlings be growing?
There will be a lot of variation depending on the variety. Here
is a general timeline to expect.
From seed, germination should be in 4 to 7 days, plants should be 1 to 2 inches tall with large cotyledon leaves at the 2 week mark.
3 weeks most plants should have the first true leaves.
4 weeks should have plants with 2 or 3 true leaves and about 3 inches tall
5 weeks would be 4 or 5 true leaves with a nice rosette developing at the growing point
6 weeks would have plants 6 inches tall with 5 or 6 true leaves and heavy normal growth
7 weeks would have plants 8 inches tall with some of the lower leaves falling off and new leaves forming at the top
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 is a good light system to use for tomatoes?
A fairly cheap setup is two or three fluorescent shop lights on a stand. You can build one or buy something workable at several of the large home building materials stores. The bulbs should be kept about 2 inches above the top of the plants. Suspending the lights so they can be raised or lowered makes this easy. If you have different sizes of plants, you might place a box or a book under the plant to raise it to an appropriate level. It is important to get fairly uniform light across all the seedlings. This reduces problems with leggy seedlings and maintains rapid growth which helps prevent damping off. Remember that fungi - like mushrooms - like dark damp places to grow. Intense light helps prevent this. High intensity lights such as halide and high pressure sodium should be used if plants larger than ten inches tall are desired. Use only bulbs designed for plants if you choose one of these systems. One problem with 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.
Fluorescent shop lights are an acceptable way to grow seedlings, but be sure to use enough bulbs of the proper output to sustain plant growth. Also, be careful about the shoplight ballasts. El cheapo shoplights mostly have magnetic ballasts which consume more electricity and are likely to fail after a few months use. Search around until you find a decent shoplight with an electronic ballast. As an added bonus, try to get a fixture that will support T8 bulbs. I use one high output white 40 watt and one high output warm white bulb in each light fixture. These bulbs are rated at 6500k. The cheap bulbs found in most box stores are 4000k or below and will not support plant growth as well as the higher output higher temp bulbs. Plants absorb a narrow range of light in the blue and red spectrums. Plant growlight bulbs are a much better option if you can handle the cost because their output is optimized in the range that plants need.
Tomatoes have type C3 chlorophyll and 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 of sustaining plant growth. As the plants grow, the lights will have to move further away which reduces the intensity levels at the leaf surface. Either increase the amount of light or adjust the position of the lights to bring the light intensity back up to a range the plants need. These are some general numbers for photo enthusiasts who might want to get into the details of plant lighting systems.
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 in their garage.
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 (7 C), and may be killed below 35 degrees (2 C). They can stand temps a bit lower but they almost stop growing until the temp is a bit warmer. Tomatoes grow best between 50F (10 C)and 75F (25 C) degrees. Greenhouse growers generally try to propagate seedlings with germination over 70 degrees but with daily growing conditions around 60F (16 C) 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?
Production of anthocyanin is a normal response for most tomato varieties. Most of us see the purple leaves and stems and think the color represents something wrong. It doesn't! This is a normal chemical produced by a plant to defend itself against excess light and pests. Guess what most of us do when we are growing seedlings indoors in winter? We put them under very bright lights that don't have the right balance of ultraviolet. So what do the plants do? Well, if they have the genetics to produce anthocyanin, then the leaves and stems turn purple. So this is a stress response, but the stressor is not cold, it is bright lights that do not have the proper amount of UV. But read on, this story continues.
The signs of cold stress are yellowing leaves, curling leaves, slow growth, and spindly stems. There are two parts to this stress. The first is caused by reduced root efficiency for absorbing potassium and phosphorus. The second is the leaves and stems which do not have effective genetic mechanisms to deal with low temps. The leaves in particular reduce transport of photosynthate and produce less plant sugars. Guess what happens when you combine bright lights with plants that are growing at less than optimum because of low temps? Well, that thing called a "stress response" happens and the plant produces anthocyanin trying to protect itself in the face of overwhelming bad growing conditions. End result, purple leaves.
Why is a tomato plant so intolerant of cold? Tomatoes originate in the tropics. They are tropical plants which we are trying to grow in a temperate (think NOT tropical) environment. There are two wild species of tomato that are able to grow at higher altitudes up to 2 miles high where temperatures routinely get down to 0°F to 15°F yet are fully hardy true perennials. So from a genetic perspective, there is a lot of room to improve cold tolerance of our tomatoes.
Purple color 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. If this happens, you can flush 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. High Anthocyanin varieties like Indigo Rose have naturally purple leaves and stems so they will show anthocyanin all the time. Ildi is a variety that never shows anthocyanin no matter how adverse growing conditions get. For growing in a greenhouse, see "What effect do gases such as ozone, ethylene, and natural gas have on tomatoes?"
What is the temperature range at which tomato plants can grow and thrive?
120°F = Severe heat, but if plenty of water is available, the plants are fine. This temp is way above levels at which pollination can take place. Plants with heavy fruit set may show stress. Nutrient transfer imbalances occur because the plant is busy moving water into leaves instead of moving nutrients into fruit.
92°F = This is the temp at which pollen starts clumping and blossoms begin to drop.
70°F to 92°F = This is the goldilocks zone. Tomatoes grow prolifically, flowers set readily, plants need maximum fertility in the soil. The high end of this range is optimum for spread of several foliage diseases.
65°F to 72°F = the best temperature to grow seedlings. Temperature can be used to slow down growth. 60°F will cause growth to be reduced about 1/4 compared to 70°F.
50°F to 65°F = this is the beginning of cold stress. Tomato plants in this range grow slowly, often produce anthcyanins (turn purple), and become pale green from loss of chlorophyll function.
32°F to 50°F = This is the range where normal tomato plants show severe cold stress. Leaves shrivel, turn yellow, wilt, stems lose turgor, roots stop absorbing water. Rubisco is deactivated by free radicals with byproducts accumulating which causes the leaves to die.
28°F to 32°F = This is the maximum range most tomatoes can withstand without freezing. Note that if frost forms on the leaves, then the leaves will freeze and die. The plant may live and can form new leaves, but the stunting effects take quite a bit of time to overcome.The time a plant can stand at this temperature is very short, in the range of about 6 hours in a 7 day period. If the temperature remains below 50 deg F on average and if the temperature dips below freezing a couple of times, the plants will deteriorate rapidly.
22°F to 28°F = This is the range that a few select varieties can withstand for brief periods of time but stipulating that frost on the leaves will still kill them.
15°F to 22°F = This is the range that a few Russian cultivars are reported to survive, again only if frost does not form. The reports I have read indicate that this tolerance is only for a limited time period, in other words, repeated low temps for 3 days or more will still kill the plants.
0°F to 15°F = A few Russian cultivars are able to handle temps this low for brief periods of time. This is the low end of the range that wild tomato species S. Habrochaites, S. Chilense, and S. Lycopersicoides can withstand.
As the temperature goes below 60°F, tomato plants enter a state where normal photosynthesis ceases. Sugar accumulates in the leaves, rubisco - a crucial chemical in the plant- begins to be deactivated by free radicles. This process causes the leaves to become dysfunctional in such a way that they can not recover. One very special trick that greenhouse growers MUST know is that if plants are exposed to overnight lows below 45°F then the greenhouse must be let rise to a high temp near 100°F the next day. If this is done, then the plants totally reverse all effects of being too cold the night before.
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 60 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.
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.
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? What on earth is a “leggy” seedling?
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. 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. 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. See the info about lighting systems for info about bulbs and plant lights.
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. Usually this type plant dies because it cannot produce any new leaves, but sometimes it will spontaneously generate a new growing point which will then produce a normal plant. Such plants will be severely delayed so under most conditions it is better to cull them as soon as they are found.
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 ordinary Sharpies. They will fade in sunlight in about 6 weeks. There is a line of sharpies available that are labelled Industrial that will last. If it is 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. An ordinary lead pencil is useful if you have plastic plant marking strips. The lead will not fade and you can erase it to re-use the marker. Just be careful if you wipe the label while it is wet, you could also remove the pencil marks!
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 size seedling is best? Mine are SO tiny!
Magic secret #1 about tomatoes:
Smaller transplants that are healthy and in the proper growth phase will outproduce larger transplants 2 to 1 or even more. Why is this? Tomatoes go through several phases of growth from the initial soft stem seedling to a rapid growth phase and then to a reproductive phase. If you set out transplants that are already in the reproductive phase, they don't grow as large or set as many flowers as the smaller plants. By comparison, the smaller plants will go through a rapid growth phase where the plant produces vigorous leaves and stems before it sets blossoms. The result is a much bigger plant that keeps expanding as it supports an increasing fruit load. The tomato growers mantra should be Small But Healthy!
Now lets deal with the special case for short season areas. You MUST set out a large plant or you won't get a crop, especially from long season varieties. For growers with this concern, plan on starting seedlings in small cells or cups, pot them up to 4 inch cups when they are about 5 or 6 weeks old, then pot them up to 1 gallon containers about 9 or 10 weeks old. Set them in the garden by 12 weeks or they will be too big to manage. The key with this is that you never let the plant get root bound and it either does not set blossoms or if it does, you get it into the ground soon enough to still have the initial growth phase. I would recommend removing all blossoms from a plant that has just been transplanted because that will give it more time to establish a root system before fruit load hits.
One last item is disease tolerance. A larger healthier plant with fruit will tolerate disease much better than a smaller plant with heavy fruit load. This is crucially important in humid climates where early blight is endemic. Setting out a plant that already has blossoms or fruit is a recipe for disaster. The plant has so much stress from trying to fill out fruit that it pulls nutrients down from the leaves which makes them very susceptible to early blight. Again, the secret is setting out healthy plants in the right growth phase.
How can I improve germination and "Wake UP" old or poor quality seed?
Old seed gradually lose viability because of oxidation of the endosperm and loss of nutrients in the embryo. If the seed are dead, they are dead, no amount of heroics will make them grow. If even a few of the seed are viable, then here are some steps that may help.
1. The most important and essential item needed is water, but not in
excess. The next most important is oxygen. Third most important is nitrate.
Fourth is a source of growth regulators like salicylic acid.
2. Prepare a seed start tray with good quality moistened seed start mix such as promix bx. This MUST be sterile mix!
3. Get some miracle grow or peters or whatever variety available of water soluble fertilizer with a high nitrate content. Mix 1/2 teaspoon fertilizer with a quart of water. Alternatively, use "tea" made from oak or tea leaves as below.
4. Saturate a paper towel with the fertilizer water and then let just enough drip out to be thoroughly wet.
5. Loosely wrap a large quantity of seed in the paper towel so that the seed are not clumped up, but are in a single layer with each seed touching the towel.
6. Place the paper towel in a ziploc bag and drop it in the refrigerator for 16 to 20 hours. The bag MUST contain air, the seed need oxygen! See instructions below to increase the oxygen level if you feel that might help.
7. Remove the seed from the paper towel and carefully sow them on top of the seed start mix well spread out so that seed do not touch each other.
8. Do NOT heavily cover the seed, instead, gather a small amount of the seed start mix and dust it over the seed so that they can still receive light but have a light dusting on top. The easiest way to do this is by putting the seed start mix in a large mesh screen kitchen sifter/strainer. The seed must be spread out so they are not touching each other, otherwise mold will be a problem.
9. Place the seed start tray in an incubator at 85 degrees for up to 20 days. A chicken egg incubator works fine for this purpose. Humidity must be kept very high. If you are using a chicken egg incubator, fill the water tray and keep it filled. If you are trying to germinate them at room temp, cover them with a sheet of plastic to prevent evaporative cooling and to keep the seed moist.
10. check the seed daily to see if any are breaking the seedcoat and if so, put them in very bright light immediately.
11. Be patient. I have had seed take up to 7 weeks to germinate.
12. Old seed that manage to germinate may have a range of problems from stuck seedcoats to missing growing points. Stuck seedcoats are easiest to remove by coating them with saliva and waiting 30 minutes, then pinching the seedcoat off. If there is no growing point but the cotyledons are healthy, wait patiently, they will often generate an adventitious shoot which will grow normally.
Increasing the oxygen content in the ziploc bag can help. I have done this by putting a cup of hydrogen peroxide in a pint jar and then adding a package of dry yeast. This releases a huge amount of oxygen which you can capture by holding the ziploc bag over the top of the jar.
To make seed tea: Get some dry oak leaves, crumble them up, then pour
1 quart of boiling water over them. Let them steep until the water
is cool, then pour the water through a strainer into a quart jar and add
1/2 of an aspirin (pure old plain generic aspirin is salicylic acid, a
plant growth regulator) and 1/2 of a teaspoon of a water soluble fertilizer
such as miracle grow. Soak a paper towel in the liquid and wring
out most of it. This also works using ordingary "tea" leaves.
The tannic acid from the oak leaves prevents mold and helps break dormancy.
The salicylic acid from the aspirin stimulates growth. The nitrate
from the fertilizer triggers the seed to initiate growth. But the
magic secret is that it contains water. Remember, no matter what
you do, you can't wake up a dead seed!