How do I maximize root size and strength in seedlings? - Page 2

bower · March 1, 2020

I mix a little bone meal into the bottom half of the pot when I transplant. This results in full pot roots every time. On one occasion I made the mistake of not mixing the bone meal down properly. At transplant time I found all the roots in the top of the pot, and none in the bottom!
I think regardless of watering habits - which really has to be tailored to how warm/cold damp/dry your environment is - the roots will seek out the P and use it if present in granular form.
Some people have perfect watering regimes where they also use liquid ferts - this didn't work for me because if it's extra cold I don't want to overwater, so I am watching and waiting to water when there's a need, never on a regular schedule. If one plant is dry, well that's the only one that gets watered, etc. However with the granular high P ferts, irregular watering does not affect root development. They are consistently good.

I've also transplanted other people's starts that were fed by liquid ferts, and the rooting was irregular - some were good but many were underdeveloped. So I think it may be more difficult to really distribute liquid ferts evenly (hats off if you can!) . Or maybe it's about root function, that makes them respond differently. With the granular, it's there in the soil and something the plant intends to mine for needed P. Forming roots is how they do that. Whereas having a liquid form of phosphorus dripping down periodically and then running off, does not localize a source of nutrients for the plant to get rooty about.

Anthony_Toronto · March 1, 2020

I always use a fan, and tops of plants are in great shape by the time they start visiting the outdoors. I think I"m going to counter-intuitively move to a balanced fert and not letting mix totally try out {*and I can see how this would be a good idea with a more soil-like mix, but with a light fluffy mix could lead to too much damage/death in roots if it dries out). I think some time in 3 to 4-inch pots would definitely do them a favour (and I confess I've often left them in the seeding tray for too long and then gone straight to 6/8/10 inch pots). Even when they get into larger pots I have them on large trays so its not too bad carting them in and out.

No matter what I do, the only thing that is really going to help them is the weather. For 4 out of the last 5 years, spring has started out unseasonably wet and cold (for tomatoes anyway), and then did an about-face and went pretty much straight into scalding heat and humidity, alternating between periods of drought or periods of downpours. Tomato plants were beaten up badly and blossom drop was rampant...so getting larger/older plants in early on was the only thing that allowed a few trusses on each to pollinate before the extremes set it. Last summer was so bad I was pulling out 90% of my plants in August.

Anthony_Toronto · March 1, 2020

Quote:

Originally Posted by bower

I mix a little bone meal into the bottom half of the pot when I transplant. This results in full pot roots every time. On one occasion I made the mistake of not mixing the bone meal down properly. At transplant time I found all the roots in the top of the pot, and none in the bottom!

That sounds like its worth a test - but I thought your secret out there was one cod tongue at the base of every plant???

Fusion_power · March 1, 2020

The secret to a healthy root system is doing everything right with your seedlings.

1. Pick the right seed for the plants you want to grow. Plants with good genetics tend to produce strong fibrous root systems.

2. Pick the right size container. Growing in a container that is either too large or too small will affect the plants. Too small is particularly damaging as the plant gets too root-bound. Very dense roots in a small cell with a large and healthy rapidly growing plant is ok. When the plant has nothing visible but a solid mat of roots, future growth is reduced and the plant may be triggered into transitioning from juvenile to adult phase. Do not let a seedling transition to adult phase! This is indicated by producing multiple clusters of flowers.

3. Use the right seed start mix. Pro-mix BX is ok but MPX gives slightly better results. Do not use contaminated seed start mix as it will cause problems with damping off.

4. The two tricks that set apart a master tomato seeding grower from the average run of the mill seed starter are: (1)deliberately let the seedlings get water stressed a couple of times as they grow, and (2)let the seedlings get down below 45F at least once before setting them out. I'll put a separate paragraph below.

5. Grow them at the right temperature. There is no single right temperature, but there is a range of temperatures that work best. From 32F to 45F is very low and causes bad things to happen in the stem while 45F to 65F is the low range. Plants can stand this temp a few times as seedlings with a caveat that it must not last more than 12 hours and must be followed by at least 12 hours of high temps. From 65 to 75 is ideal tomato seedling temp. From 75 to 95 will usually involve some moisture stress so the seedlings may slow down a bit. From 95 to 120 is high but completely acceptable so long as the plants have plenty of water. They may not grow as fast as at lower temperatures, but they will change physiologically, particularly the stem of the plant.

6. Make sure they are getting enough light of the right spectrum. With indoor grow lights, there will be problems if the plants are grown larger than about 8 inches tall. Use specialty grow light bulbs if this is the case! I have to use shade cloth to reduce the light levels in my greenhouse. The key here is balance.

7. Use appropriate fertilizer. Miracle grow for tomatoes works fairly well if used in moderation. I am using a general purpose liquid fertilizer with micronutrients from Walmart. I use 1/4 teaspoon per tray of 48 seedlings with a caveat that Miracle Grow MPX has some nutrients to get seed started. If growing seedlings more than 8 inches tall, more fertilizer will be needed!

8. Thigmotropism! This is the effect where a seedling changes growth pattern as a result of being touched. Seedlings that are regularly stimulated - such as by a fan flowing across them - develop stronger stems and are healthier than otherwise. Brushing a broom handle across a large number of seedlings is one way to do this.

Deliberately letting seedlings get a bit dry has two physical effects. The plant will slow down growing above the surface and it will expand the root system looking for water. Do NOT starve them for water! Let the plants dry to the point the leaves start to wilt, then water them very well. Do this twice and the root system will get twice as large as an unstressed seedling.

I can leave the greenhouse doors and vent closed and the spring temperature can easily reach 120F. The way I manage temperatures is to deliberately let the seedlings get down between 32F and 45F then push the temperature the next day up to between 90F and 120F. This has the net effect of reversing the impact of very cold temperatures the night before but the plants retain the effect which causes them to be more productive as adults. Look this up. A study done nearly 100 years ago showed that seedlings deliberately treated with low temperatures are much more productive than plants kept at high temps.

imp · March 1, 2020

Very clear and solid information Fusion and a thanks from me as I shall follow through or try to follow some of your advice.

bower · March 1, 2020

Quote:

Originally Posted by Anthony_Toronto

That sounds like its worth a test - but I thought your secret out there was one cod tongue at the base of every plant???

indeed it is b'y. we only call it 'bone meal' to be polite.

aclum · March 2, 2020

Darrel, I really appreciate all the great information you post! Thank you so much.

I was wondering if you could elaborate more on the following statement:
----------------------------------------
The way I manage temperatures is to deliberately let the seedlings get down between 32F and 45F then push the temperature the next day up to between 90F and 120F. This has the net effect of reversing the impact of very cold temperatures the night before but the plants retain the effect which causes them to be more productive as adults.
-----------------------------------------

If my nighttime temps outside or in the garage are in the high 30's to mid-high 40's range, might it make sense to put them outside at night (for less than 12 hours at these temps), then bring them indoors under a dome and on a heating pad to maintain temps at 90-100 under strong light during the day? How long would they stay at the high temp to compensate for the overnight cold?

If this is done, would it be a one or two time thing or for a continuous period?

I read somewhere about vernalization which is done sometime between the cotyledon and first true leaf stage. Would this be the case in what you suggested?

This procedure seems quite different from the cold treatments that you and Keith Meuller (?) have discussed in the past (and which would be unworkable in my particular situation). In that case, the particular procedure was started after the first leaf and lasted for a couple of weeks (iirc).

Also, will the procedure you mentioned also contribute to decreasing the interval between nodes in the adult plant?

Thanks for any additional information

! I really don't need great yields (doctor said to go easy on tomatoes

) but I like to experiment - and brag on occasion

.

Anne

Anthony_Toronto · March 2, 2020

Quote:

Originally Posted by Fusion_power

The secret to a healthy root system is doing everything right with your seedlings...

Much appreciated!!

One thing I would say for my climate is that the only thing that has saved my season in recent memory is getting plants that have transitioned to adult phase into the garden. If I hadn't done so (and for the plants that hadn't made it that far, or the younger plants that I'd purchased from garden centres) I would have had essentially no crop. That being said, in ideal conditions, I much prefer the way that a younger plant grows from set out, vs. an older larger plant, even if I give it as much care as I can before set out. Luckily for me, this year I have enough spare time for the time being that I can start some seeds early to help accommodate for any weather craziness, and start some seeds later, to get them in the ground at the proper age, and have them go through more growth stages in the ground/exposed to the elements for a longer period of time. Win-win, and a good experiment.

As for the water stress, once I started incorporating this into my seedling process, my roots counter-intuitively worsened (i.e. much weaker/sparse root structure) instead of getting better; this year I'll plan to do this for some plants and not for others, and track how they do.

Cheers...

Fusion_power · March 2, 2020

Aclum, cold treatment of tomato plants works if done just once or twice while they are seedlings, preferably after they are about 4 inches tall but before they set flower buds. The length of time a seedling spends below 45F should be the length of time they spend above 90F the next day to reverse the stunting effects of cold temperatures. If the plants are not brought above 90F the next day, the plants will sulk and refuse to grow for a week or two even if they are at 80F from that point on. There is a genetic component to this with some varieties handling low temps much better than others. Sub Arctic Plenty for example handles cold temps very well where most others struggle.

Anthony, Growing seedlings indoors past juvenile transition is acceptable so long as they are potted up to a larger container prior to the transition. "Larger" in this case means 3 gallons or more. The roots need that much room to expand and the soil mix used should have a lot of nutrients such as from good quality compost.

Anthony_Toronto · March 2, 2020

Quote:

Originally Posted by Fusion_power

Anthony, Growing seedlings indoors past juvenile transition is acceptable so long as they are potted up to a larger container prior to the transition. "Larger" in this case means 3 gallons or more. The roots need that much room to expand and the soil mix used should have a lot of nutrients such as from good quality compost.

My 10-inch pots with plants that often have 1-2 (unopened) flowers fall a little short of 3 gallons, but so far don't appear to be negatively impacted, in clear contrast to similarly sized (but likely more mature) plants that I get almost every year from garden centres, that soooo clearly prove what you're saying!! I don't know why I do it but I usually supplement with a few big lovely plants each year from garden centres...always looking healthy and sturdy and already hardened off...and without fail, the smaller plants that I set out always catch up to those big garden centre starts, and then pass them, with the big garden centre starts hitting the wall earlier in the season than my starts. Even if my starts are the same size, its clear that the big garden centre starts are older, and have materially suffered from not being in the ground sooner. And this is even with plants of the same varieties that I'm growing side by side. I do have at least a few nice large pots that I can test out on my earliest starts to see if they perform better than those in 10-inch pots. Hopefully this year I will have the willpower to steer clear of those big garden centre starts, but I think we all get moments of excitement and weakness when the season starts!

kath · March 2, 2020

Quote:

Originally Posted by Fusion_power

The secret to a healthy root system is doing everything right with your seedlings...

Bet I'm not alone in saying that if you wrote a book about gardening, I'd buy it! Your posts have been among the most valuable that I've encountered here since I joined a decade ago. Thank you for all the time you spend helping those of us who are trying to grow a better garden.

kath

aclum · March 2, 2020

Thanks Darrel! BTW, I totally agree with Kath!!

Anne

bower · March 6, 2020

Yeah Darrell, me three! Your advice has been invaluable to me.

FWIW I will mention that in my own context, that is growing only tomato varieties that tolerate cooler conditions, my seedlings grow just fine at a median temperature of 60 F, with lows down to 50 F at night and up as high as 70 F only if there's a sunny day in the window - not more than once a week here in March.
In years when I was trialing a lot of varieties to find the cold tolerant ones, there were definitely some varieties that did not thrive in those conditions, and may have performed poorly because of their stressful seedling days.

I just wanted to comment that there are some varieties which seedlings can take a steady diet of temperatures below 65 F without being overly troubled. That is thanks to the amount of variation in the tomato genome.

In the greenhouse, 48-50 F is my benchmark for minimum night temperature without protection, but there are always some nights down to 45 where I hope to see a sunny day and a nice high temperature afterwards to make up for the extra stress.

The best advice I ever got was to transplant when there were three fine days in a row, so that the plants weren't forced to deal with cold stress and transplant stress at the same time. Thank you Dar for this and other insights.

BigVanVader · March 6, 2020

Bottom water, don't fertilize.

Harry Cabluck · March 7, 2020

Anybody...When you uppot your seedlings, do you pick out around at the roots that have grown in a circle inside your smaller pot?

March 1, 2020	#19
Fusion_power Tomatovillian™ Join Date: Feb 2006 Location: Alabama Posts: 2,250	The secret to a healthy root system is doing everything right with your seedlings. 1. Pick the right seed for the plants you want to grow. Plants with good genetics tend to produce strong fibrous root systems. 2. Pick the right size container. Growing in a container that is either too large or too small will affect the plants. Too small is particularly damaging as the plant gets too root-bound. Very dense roots in a small cell with a large and healthy rapidly growing plant is ok. When the plant has nothing visible but a solid mat of roots, future growth is reduced and the plant may be triggered into transitioning from juvenile to adult phase. Do not let a seedling transition to adult phase! This is indicated by producing multiple clusters of flowers. 3. Use the right seed start mix. Pro-mix BX is ok but MPX gives slightly better results. Do not use contaminated seed start mix as it will cause problems with damping off. 4. The two tricks that set apart a master tomato seeding grower from the average run of the mill seed starter are: (1)deliberately let the seedlings get water stressed a couple of times as they grow, and (2)let the seedlings get down below 45F at least once before setting them out. I'll put a separate paragraph below. 5. Grow them at the right temperature. There is no single right temperature, but there is a range of temperatures that work best. From 32F to 45F is very low and causes bad things to happen in the stem while 45F to 65F is the low range. Plants can stand this temp a few times as seedlings with a caveat that it must not last more than 12 hours and must be followed by at least 12 hours of high temps. From 65 to 75 is ideal tomato seedling temp. From 75 to 95 will usually involve some moisture stress so the seedlings may slow down a bit. From 95 to 120 is high but completely acceptable so long as the plants have plenty of water. They may not grow as fast as at lower temperatures, but they will change physiologically, particularly the stem of the plant. 6. Make sure they are getting enough light of the right spectrum. With indoor grow lights, there will be problems if the plants are grown larger than about 8 inches tall. Use specialty grow light bulbs if this is the case! I have to use shade cloth to reduce the light levels in my greenhouse. The key here is balance. 7. Use appropriate fertilizer. Miracle grow for tomatoes works fairly well if used in moderation. I am using a general purpose liquid fertilizer with micronutrients from Walmart. I use 1/4 teaspoon per tray of 48 seedlings with a caveat that Miracle Grow MPX has some nutrients to get seed started. If growing seedlings more than 8 inches tall, more fertilizer will be needed! 8. Thigmotropism! This is the effect where a seedling changes growth pattern as a result of being touched. Seedlings that are regularly stimulated - such as by a fan flowing across them - develop stronger stems and are healthier than otherwise. Brushing a broom handle across a large number of seedlings is one way to do this. Deliberately letting seedlings get a bit dry has two physical effects. The plant will slow down growing above the surface and it will expand the root system looking for water. Do NOT starve them for water! Let the plants dry to the point the leaves start to wilt, then water them very well. Do this twice and the root system will get twice as large as an unstressed seedling. I can leave the greenhouse doors and vent closed and the spring temperature can easily reach 120F. The way I manage temperatures is to deliberately let the seedlings get down between 32F and 45F then push the temperature the next day up to between 90F and 120F. This has the net effect of reversing the impact of very cold temperatures the night before but the plants retain the effect which causes them to be more productive as adults. Look this up. A study done nearly 100 years ago showed that seedlings deliberately treated with low temperatures are much more productive than plants kept at high temps. Last edited by Fusion_power; March 1, 2020 at 12:19 PM.

March 1, 2020	#20
imp Tomatovillian™ Join Date: Apr 2009 Location: Wichita Falls, Texas Posts: 4,832	Very clear and solid information Fusion and a thanks from me as I shall follow through or try to follow some of your advice. __________________ I'm not a complete idiot, some parts are missing.

March 2, 2020	#24
Fusion_power Tomatovillian™ Join Date: Feb 2006 Location: Alabama Posts: 2,250	Aclum, cold treatment of tomato plants works if done just once or twice while they are seedlings, preferably after they are about 4 inches tall but before they set flower buds. The length of time a seedling spends below 45F should be the length of time they spend above 90F the next day to reverse the stunting effects of cold temperatures. If the plants are not brought above 90F the next day, the plants will sulk and refuse to grow for a week or two even if they are at 80F from that point on. There is a genetic component to this with some varieties handling low temps much better than others. Sub Arctic Plenty for example handles cold temps very well where most others struggle. Anthony, Growing seedlings indoors past juvenile transition is acceptable so long as they are potted up to a larger container prior to the transition. "Larger" in this case means 3 gallons or more. The roots need that much room to expand and the soil mix used should have a lot of nutrients such as from good quality compost. Last edited by Fusion_power; March 2, 2020 at 01:24 PM.

March 1, 2020	#16
bower Tomatovillian™ Join Date: Feb 2012 Location: Newfoundland, Canada Posts: 6,793	I mix a little bone meal into the bottom half of the pot when I transplant. This results in full pot roots every time. On one occasion I made the mistake of not mixing the bone meal down properly. At transplant time I found all the roots in the top of the pot, and none in the bottom! I think regardless of watering habits - which really has to be tailored to how warm/cold damp/dry your environment is - the roots will seek out the P and use it if present in granular form. Some people have perfect watering regimes where they also use liquid ferts - this didn't work for me because if it's extra cold I don't want to overwater, so I am watching and waiting to water when there's a need, never on a regular schedule. If one plant is dry, well that's the only one that gets watered, etc. However with the granular high P ferts, irregular watering does not affect root development. They are consistently good. I've also transplanted other people's starts that were fed by liquid ferts, and the rooting was irregular - some were good but many were underdeveloped. So I think it may be more difficult to really distribute liquid ferts evenly (hats off if you can!) . Or maybe it's about root function, that makes them respond differently. With the granular, it's there in the soil and something the plant intends to mine for needed P. Forming roots is how they do that. Whereas having a liquid form of phosphorus dripping down periodically and then running off, does not localize a source of nutrients for the plant to get rooty about.

March 1, 2020	#17
Anthony_Toronto Tomatovillian™ Join Date: Jun 2010 Location: Toronto Posts: 413	I always use a fan, and tops of plants are in great shape by the time they start visiting the outdoors. I think I"m going to counter-intuitively move to a balanced fert and not letting mix totally try out {*and I can see how this would be a good idea with a more soil-like mix, but with a light fluffy mix could lead to too much damage/death in roots if it dries out). I think some time in 3 to 4-inch pots would definitely do them a favour (and I confess I've often left them in the seeding tray for too long and then gone straight to 6/8/10 inch pots). Even when they get into larger pots I have them on large trays so its not too bad carting them in and out. No matter what I do, the only thing that is really going to help them is the weather. For 4 out of the last 5 years, spring has started out unseasonably wet and cold (for tomatoes anyway), and then did an about-face and went pretty much straight into scalding heat and humidity, alternating between periods of drought or periods of downpours. Tomato plants were beaten up badly and blossom drop was rampant...so getting larger/older plants in early on was the only thing that allowed a few trusses on each to pollinate before the extremes set it. Last summer was so bad I was pulling out 90% of my plants in August.

March 2, 2020	#22
aclum Tomatovillian™ Join Date: Feb 2010 Location: Merced, CA Posts: 832	Darrel, I really appreciate all the great information you post! Thank you so much. I was wondering if you could elaborate more on the following statement: ---------------------------------------- The way I manage temperatures is to deliberately let the seedlings get down between 32F and 45F then push the temperature the next day up to between 90F and 120F. This has the net effect of reversing the impact of very cold temperatures the night before but the plants retain the effect which causes them to be more productive as adults. ----------------------------------------- If my nighttime temps outside or in the garage are in the high 30's to mid-high 40's range, might it make sense to put them outside at night (for less than 12 hours at these temps), then bring them indoors under a dome and on a heating pad to maintain temps at 90-100 under strong light during the day? How long would they stay at the high temp to compensate for the overnight cold? If this is done, would it be a one or two time thing or for a continuous period? I read somewhere about vernalization which is done sometime between the cotyledon and first true leaf stage. Would this be the case in what you suggested? This procedure seems quite different from the cold treatments that you and Keith Meuller (?) have discussed in the past (and which would be unworkable in my particular situation). In that case, the particular procedure was started after the first leaf and lasted for a couple of weeks (iirc). Also, will the procedure you mentioned also contribute to decreasing the interval between nodes in the adult plant? Thanks for any additional information ! I really don't need great yields (doctor said to go easy on tomatoes ) but I like to experiment - and brag on occasion . Anne

March 6, 2020	#28
bower Tomatovillian™ Join Date: Feb 2012 Location: Newfoundland, Canada Posts: 6,793	Yeah Darrell, me three! Your advice has been invaluable to me. FWIW I will mention that in my own context, that is growing only tomato varieties that tolerate cooler conditions, my seedlings grow just fine at a median temperature of 60 F, with lows down to 50 F at night and up as high as 70 F only if there's a sunny day in the window - not more than once a week here in March. In years when I was trialing a lot of varieties to find the cold tolerant ones, there were definitely some varieties that did not thrive in those conditions, and may have performed poorly because of their stressful seedling days. I just wanted to comment that there are some varieties which seedlings can take a steady diet of temperatures below 65 F without being overly troubled. That is thanks to the amount of variation in the tomato genome. In the greenhouse, 48-50 F is my benchmark for minimum night temperature without protection, but there are always some nights down to 45 where I hope to see a sunny day and a nice high temperature afterwards to make up for the extra stress. The best advice I ever got was to transplant when there were three fine days in a row, so that the plants weren't forced to deal with cold stress and transplant stress at the same time. Thank you Dar for this and other insights.

March 6, 2020	#29
BigVanVader Tomatovillian™ Join Date: Mar 2014 Location: Greenville, South Carolina Posts: 3,099	Bottom water, don't fertilize.

March 7, 2020	#30
Harry Cabluck Tomatovillian™ Join Date: Jan 2018 Location: Austin, Texas Posts: 217	Anybody...When you uppot your seedlings, do you pick out around at the roots that have grown in a circle inside your smaller pot?