Growing Seedlings in flats

[snappybob]

I'm fairly experienced in growing seedlings. I start a lot of tomatoes and peppers every year to sell to friends, co workers and some farmers market growers. I start them out in the little six packs sowing a half dozen or so seeds per cell and then transplanting to 4 inch pots and growing them out to sell or plant in my garden. I have a customer who would like me to start and grow out to transplant size two varieties of peppers in 96 cell flats. One flat for each variety. I am looking for pointers on what I may need to do differently with this method of growing. Will I have to feed periodicly since the plant will have much less medium to draw nutients from? I'm sure diligent watering will be a must since the small cell will tend to dry out quickly with a big root system drawing from it. I grow in a small green house that is heated at night when nessesary. I usually start my plants around the third week of January. Will seedlings grown this way grow faster, slower or at the same rate? I am looking forward to getting some experience at growing with this method. I'd like to get some advice to avoid any pitfalls that may be on the horizon. Thanks in advance for any help.

[Keger]

Might want to check with a local greenhouse, commercial type, for tips. I have one here I work with a lot. They start theirs as plugs, in trays of 288. I think patience is the deal with some good light. They keep them as plugs 4 weeks, then into 4" pots for 4 weeks. At 8 weeks, ready to sell. They dont water unless there is food in the water. Their system is set up like that. I water my new stuff with Miracle grow and it blows up pretty good, as there are 0 nutrients in seed starter mix. I use plain water at planting and a spray bottle until the stems are a little thick and fuzzy, then the Grow solution.

[moon1234]

Originally Posted by Keger

Might want to check with a local greenhouse, commercial type, for tips. I have one here I work with a lot. They start theirs as plugs, in trays of 288. I think patience is the deal with some good light. They keep them as plugs 4 weeks, then into 4" pots for 4 weeks. At 8 weeks, ready to sell. They dont water unless there is food in the water. Their system is set up like that. I water my new stuff with Miracle grow and it blows up pretty good, as there are 0 nutrients in seed starter mix. I use plain water at planting and a spray bottle until the stems are a little thick and fuzzy, then the Grow solution.

I grew 10 to 12, 72 cell plug trays worth this year of tomatoes and 6-72 cell peppers. It is NOT true that growing medium does not have fert. MOST good ones will have a starter charge that is designed to get seedlings to the first true leaves. You should NOT use miracle grow for young seedlings. MOST fert sold in home stores will have most of the nitrogen in an ammonia based form. This will cause stretch in your seedlings.

It is best to feed with Calcium Nitrate ONLY until they have four true leaves. You can THEN use a weak complete fertilizer (10-10-10, etc.) once a week and alternate with calcium nitrate. The key is to produce short, stocky plants. You do not want tall lush plants for transplanting.

I grow from seed to transplant in the 72 cell trays. They work great.

Peppers are a little harder as the seed needs to stay warm for at LEAST 2-3 weeks until you have good emergence. This means you need a germination chamber or bottom heat to keep the SOIL at a constant 80-85 degrees until you have full emergence. Once you have good emergence then grow on the same as tomatoes. Peppers need 10-12 weeks for good transplant size or you will not get peppers until late in the season in the north.

Choose growing mix such as Fafard, Pro-Mix or similar. I use Fafard GM-1 and mix rice hulls in to replace the perlite and vermiculite. Most growers I know start early tomatoes in 72 cell plug trays and later season toms in 128. We transplant with either water wheel transplanters or a normal holland style transplanter.

Gowing in 4" pots is more for retail consumers who think bigger plants are better.

[Keger]

Guess there's several different ways to do things huh?

[ilex]

If you have the space, I would use bigger trays with more space for the seedlings. You'll get better quality than comercial ones. At least here in Spain, comercial seedlings are skiny and really crowded.

If it's only a few flats you can go for the quality, if it's a big business, you'll have to find a compromise between space used and plants sold.

[clkeiper]

I would not agree to growing in the 96 size for anybody as a "finished" plant. they really need the soil mass to keep from dying if someone forgets to water them for a day. Moon is correct in giving peppers more grow time than tomatoes. I always plan on 10-12 weeks for the crop AFTER they are germinated. I germinate them on a heat mat, too. Otherwise I don't get a very good germination rate. You may not need to there depending on the night temperatures....but I would still plan on having one just in case it is cool at nighttime.

[moon1234]

I have had at least six people respond to me asking about Calcium Nitrate so far. Here is the message I have sent back so others may benefit:


You did not state how many plants you start. This will sort of dictate what fertilizers make economical sense to you. Calcium Nitrate comes as a dry fertilizer. The greenhouse grade is in crystal form and looks like table salt. I buy around 500 to 1000 lbs per year. It comes in 50lb bags. The most common brand in my area is Yara. Nolt's produce supplies or Nolt's Midwest produce supplies sells it for a reasonable price if you are on the east coast or Midwest.

If you don't need that much, then there is a brand called Jack's fertilizer that is sold at many greenhouses and lawn and garden centers. Look at the label, one of them is just plain Calcium Nitrate, but you will pay about 5x more per lb to get in in the small 1lb and 5lb containers.

10-10-10 or any complete fertilizer can be bought anywhere, but I avoid all of the stuff at the big box stores. Miracle Grow, Schultz's, etc. has Urea as one of the main Nitrogen components. Urea will burn young seedlings if you top water and get the leaves wet, which almost everyone does. I buy either Millers complete or Plant Marvel 20-10-20 Complete now. Whichever is cheaper, which is usually Plant Marvel. These can be bought from Nolt's as well.

The 20-10-20 I apply by either using a half teaspoon per gallon of water in a watering can or I mix a concentrated solution of 100x normal strength and then use a chemilizer injector that has a dilution ratio of 1:100. This way I can mix a concentrate solution in a 5 gallon bucket and then use the normal watering wand with the hose to fertilize the flats. It saves a HUGE amount of time. Next year I will add the little drop nozzles you see in the larger greenhouses so I can just set the timer to water for me and avoid manual watering for the most part.

For Calcium Nitrate and a complete fertilizer I will start with 100ppm Nitrogen as my goal until the plants have 6 to 8 leaves, then move to 150ppm nitrogen until ready to go to the field. The 50lb bags of fertilizer will have a table on them that tells you how many ounces or pounds to add to a gallon of water for a concentrate. Most greenhouses use a 1:100 chemical injector that pulls one ounce of fertilizer concentrate per 100 ounces of water. The person mixing the concentrate then looks on the table under the 1:100 column and goes down to 100ppm or 150ppm and finds out how many ounces or lbs to add to each gallon of water. You will need to do some simple math if you are not using a chemical injector.

If you are using a watering can, then you will need to look under the 1:100 column of the table and divide the weight stated by 100 to get the amount to add for direct application in a watering can. Hopefully that is easy enough.

Here is an example from Plant Marvel's website: http://www.plantmarvel.com/201020_ge...e_tech_sht.pdf

If you are growing more than a few trays you should also own an EC (electrical conductivity) meter. It will allow you to approximate the fertilizer concentration in your solution tank AND the concentration in your applied water. They are simple to use. Simple measure the EC of the tap water coming from your hose before any fertilizer. Then measure the EC in the fertilizer concentrate or coming from the end of the hose. You then subtract the lower number from the higher number to get your EC. Look on the fertilizer bag or the tech sheet and see what EC matches which concentration. It is not exact, but close.

What experienced growers do is check the EC on the drain water from their plants. This tells you want the approximate EC is in your soiless media and what is there for the plants. Many people do not realize how quickly plants will absorb nutrients or if they are over fertilizing. The simple way to do this is to use pure water (distilled with an EC of 0 or very low), then put a disk or tray under the flat and water the flat until you get a fixed amount of water out the bottom of the tray, then measure the EC in this water. This is essentially leeching nitrogen from the tray so you can see what was left for the plants. If you use a fixed amount of water each time then you will see if the plants are using more or less fertilizer than you are applying. If the EC goes UP each time you check then you know you have salt buildup in your tray. Too much salt can damage the roots of plants. Just use plain water the next time and leech the extra salt out. If the EC is always low then your plants are using all the nutrients (well nitrogen anyway) and are still wanting more.

I am sorry if this all seems overly complex. I start around 100,000 transplants each year now (not all tomatoes) so doing things by hand is more than a full time job and I need to automate. We started around 1800 tomatoes and 5000 peppers this year.

One thing to keep in mind is that none of the greenhouses use "potting mix". That is what is sold in the big box stores to consumers. It is never used by greenhouses. "Soilless Media" is what most greenhouses will use. Pro-Mix BX is the most popular in my area, but Metro-Mix is also popular. I don't like perlite and vermiculite due to their dusty and non-renewable nature (they are both mined products). I use Fafard GM-1 soilless media (Peat Moss, Limestone, Starter Nutrients and wetting agent) and then I mix in Parboiled Rice Hulls. Rice hulls are from Riceland (like you buy in the grocery store). They are the hull that the rice grain grows in. The rice hulls replace the perlite and vermiculite for me and have worked well, are bio-degradable and cheaper than perlite and vermiculite. If you live in an area where you can buy compost at a reasonable cost then that would work as well. Vermont Compost is one company that sells compost with a guaranteed analysis. The nice part about their compost is that it will provide all of the nutrients required for about four weeks of growth provided that it does not get too hot (which increases growth rate and nutrient requirements) or you over water and leech out the nutrients being mineralized by the bacteria in the compost.

Hope that was not too much information.