early cold treatment, anyone?

[kath]

Lakelady, mine were in the basement for a few weeks and were very purple and now have been in the greenhouse/outside on warm days and the lower leaves are still purple- it's only the new growth that is the normal color. I don't remember if the old leaves ever turn completely green again.

[z_willus_d]

It's been my experience that the leaves which turn extremely purple often start to exhibit other issues and ultimately die. I don't know if this is directly related to the purple or just coincident. I've never seen the purple subside to green once apparent.
-naysen

[bower]

Some of my plants with purplish underside of leaves (and very purple stems) also had yellowish blotches on the older leaves. A feed of fish emulsion/molasses and a couple of days above 70 F, and those leaves are now all green - but there are still purple traces on the undersides. Mind you it is still around 40 F in the greenhouse every night, and we had one day that didn't crack 50 F when the greenhouse was snowcovered and dark... tough times, but they do seem to be hanging in there.

Since some of these plants already have 3 sets of true leaves, I've been wondering whether there is any reason to keep em in their pots any longer, instead of planting them into the big containers which will be their final home, in the same greenhouse. Any advice on that?

[willyb]

Hi Bower,

I have similar conditions here in Alberta as you speak of. My GH swings from 40 at night to over 100 some days and all temps in between. Many of my plants were some stage of purple at all stages. I transplanted many to bigger pots. They are looking good. I don't see any more loss with plants with purple leaves. I say. " If they can't take the Canadian climate, let them die" and nurture the tough ones for better seed stock. My issue is more with the cultivator. Most of my losses was with a pack of Mortgage Lifter seeds. Not the variety, I think, just poor seeds.

Brad

[bower]

Thanks WillyB,
It's great to know someone with similar conditions. I have just a little more work to do to recondition the soil in the containers, and I'll put them right in.
Too bad my compost pile is still frozen solid! I may have to buy some.
I was reading about minimum temps for growth of different crops, and it turns out the present greenhouse range a bit low for tomatoes is fine for summer squash, so I have a dozen plants started to get in there asap as well.

[ljp]

My tomatoes look healthy; but, I haven't seen much growth. They have been in the greenhouse since the first week of April. Lows with heat have been about 10C and without 4-5C. Mornings tend to be 12-15C. Afternoon temperatures hit 30C. Is it the cool nights that are holding them back?

[bower]

I planted my cold treated tomatoes in the tubs and I have been monitoring the day and night temps and keeping a record to compare outdoor and indoor temps. When it's -1 C outdoors I can expect a low of 8 C in the greenhouse. (not heated).
ljp, I didn't see any growth in my plants at temperatures you described either. They just got more purple! But they have really greened up since then and don't appear harmed by it - really very nice sturdy plants.

We've been having a little april heatwave here, way warmer than normal. I haven't had an overnight low of less than 50 F (the magical 10 C) since April 15. Daytime highs are in the good growing range with minimal sunshine, and I've been having to manage the sunny high temperatures with ventilation and a couple of fans. I did move the big tubs into the sunniest area to maximize the heat gain and retention.

All my cold treated plants unfurled their first cluster of flower buds on the same day ( the ones I started Feb 2 are maybe 6 inches bigger - and more purple on the stem - than those started Feb 22, but not more mature). As of today, there are fully open blossoms on Stupice (the first), Moravsky Div, Violet Jasper (all feb 22 starts). So I am now concerned about blossom drop - since our forecast is for outdoor lows of 0 C for the next two nights and -3 the night after! All of these outdoor lows could drop my greenhouse temp below 10 C (50 F).
(ljp, I always think the mainland is warmer than here, but it's obviously not the case, at least this year. Edmonton is far north, I think!)

So now I'm wondering... does that cold treatment help the plants to endure lows outside the 'prescribed' range for setting flower and fruit? I've heard that Stupice sets fruit in cold weather but not sure about the others. I also don't know whether buds may be harmed by temps of 8C (47 F) or less? I really don't care about catfacing, but I do want my early fruit!

One trick I used on a cold night (of panic!) was I took my recycle bag of juice boxes/bottles and filled them all with hot water, then placed them on the soil surface in the tubs between two tomato plants. In the morning the bottles were cold but the greenhouse temp had not dropped below 50 F as I feared. I left the bottles there, and I notice they are warm in the evening and cold in the morning. So it seems a good small mass to take up heat in the day and release it during the night. I'm planning to maybe organize better that kind of small heat storagre mass for solar capture and release. Also considering using row cover over the plants on that -3C outdoor night...

[moon1234]

Originally Posted by bower

Some of my plants with purplish underside of leaves (and very purple stems) also had yellowish blotches on the older leaves. A feed of fish emulsion/molasses and a couple of days above 70 F, and those leaves are now all green - but there are still purple traces on the undersides. Mind you it is still around 40 F in the greenhouse every night, and we had one day that didn't crack 50 F when the greenhouse was snowcovered and dark... tough times, but they do seem to be hanging in there.

Since some of these plants already have 3 sets of true leaves, I've been wondering whether there is any reason to keep em in their pots any longer, instead of planting them into the big containers which will be their final home, in the same greenhouse. Any advice on that?

This is a very old thread, but I was reading it and thought people might benefit from some information. Purple color to the leaves is almost always a phosphorus deficiency. This can be caused by a few factors. If you don't fertilize your plants properly, and many who area all organic can't as the sources of fertilizer and not 100% available to the plant right away.

Nitrogen is required by all plants, almost exclusively, when they are young. It modulates the uptake of almost all of the other nutrients. You could be feeding your plants a high phosphorus fertilizer and the purple won't be corrected on new leaves if there is not enough Nitrogen.

Purple color to the leaves usually won't go away as phosphorus is not normally transported into older leaves, only new growth. There must be a sufficient amount of phosphorus available as the plant grows in the plug tray or container. If you correct the fertility and new leaves are green and don't exhibit purplish tint then the problem is corrected.

We usually feed at 100 ppm Nitrogen and Potassium until the plants have their first true leaves. Then we do one feed per week of a fertilizer that has phosphorus at a rate of 30ppm. This phosphorus amount is continued until they are transplanted into the field 8-10 weeks later. Nitrogen and Potassium are upped to 150ppm per week once the plants are 6 weeks old.

Our fertilizer sources are:
Nitrogen: Calcium Nitrate, Potassium Nitrate
Phosphorus: 20-10-20 (Plant Marvel Complete or Millers Complete)
Potassium: Potassium Nitrate

We try to avoid Amonia and Urea Nitrogen sources as they cause a lot of stretch in tomatoes at early stages. It is hard enough to keep them short when in high density plug trays.

Knowing how much fertilizer to add to get to a particular PPM is easy math:

Desired PPM
--------------
% Nutrient x 75

This will give you the amount to add per US gallon of water. If mixing small amounts it is easier to use a 4 or five gallon bucket and a kitchen or postal scale for weights.

If you look at a fertilizer label you will see 20-10-20 or similar numbers. They are listed in order Nitrogen - Phosphorus - Potassium. Nitrogen is always 100 available. Phosphorus is not in a 100% plant usable form in the bag. You must divide the number by 2.3 to get the right amount. Potassium is also not 100% available, you must divide by 1.25. Always start with the nutrient that not available in other fertilizers. Usually this means phosphorus, then potassium and finally nitrogen.

Example:

Requirement: Fertilize tomatoes with 100 ppm of Nitrogen and Potassium, no Phosphorus. Your fertilizers are Calcium Nitrate (15.5-0-0 18% calcium) and Potassium Nitrate (13.75-0-48).

Calculations:
Potassium needed: 100ppm

48/1.25 = 38.5% available potassium in Potassium Nitrate (13.75-0-48).

100
--------------- = .034 oz / gallon of water.
38.5 x 75

Nitrogen contributed by potassium nitrate would be:

13.75 x 75 x .034 = 35ppm

Nitrogen Needed: 100ppm

15.5% available nitrogen in Calcium Nitrate (15.5-0-0 18% Calcium)

100ppm - 35ppm = 65ppm (35ppm from Potassium Nitrate above)

65
------------ = .056 oz / gallon of water
15.5 x 75

Solution:
Add the following amounts per US gallon of water:

.034 oz Potassium Nitrate
.056 oz Calcium Nitrate

Using a 4 or five gallon bucket is highly suggested as the amount of fertilizer will be increased and easier to weigh.

Read some of the university trials and greenhouse grower information sheets. Almost all nutrient sources are listed in PPM of nutrient at a specific grow stage.

Organic inputs usually don't have a fixed amount of any particular nutrient so it is hard to know how much to add to your grow mix or soil. Some that do work are Fish Emulsion and Chilean Nitrate. I will warn you that fish emulsion STINKS. You will smell like a swabbie if you use it in your greenhouse routinely.

If you are fertilizing a LOT of plants a small chemical injector can be really handy. These devices suck a concentrated solution from a bucket and mix with water at a predetermined rate. I have a chemilizer that has a 1:100 dilution ratio. Meaning I mix the fertilizer concentrate 100 times stronger. Use the same calculations as about and then multiply by 100 to know how much to put in a bucket. The injector will draw a small amount out and mix with water as it flows through to get the desired rate.

This all seems like a lot, but I promise you it is easy. I made a simple sheet with my crops that lists growth stage (1-4) and fertilizer needs. I don't need to do any math and just mix up what I need, turn on the hose and water with the correct amount of fertilizer.

P.S.
Growth Stages are usually:
1: Radical emerges
2: Cotyledons emerge
3. Second Set of True leaves appear
4. Final stage until transplant/pot up.

Growth stages will vary with crop and as you gain experience, you will be able to make up your own sheets with your preferred inputs.

My hints:
- Fertilize with EVERY watering at a lower rate. If the weather turns cold and cloudy and you can't water for 3-5 days you want your plants to have enough nutrition to make it through v.s. needed to water to apply nutrients.

- Never use fertilizers with high amounts of Ammonical or Urea Nitrogen (Miracle Grow, Schultz's veggies, etc.). These are cheap sources of nitrogen and cause stretch in young plants and can burn at higher rates.

- ALWAYS do a quick sprinkle with clear water after fertilizing before the fertilizer solution has a chance to dry on the leaves. Some fertilizers, especially complete fertilizers, can burn foliage if left to dry on the leaves.

- Never use potting soil from the garden center to start seeds or young plants. These usually have polymers or large amounts of vermiculite in them to help retain water. This results in damping off from staying too wet or algae starts growing on the top of the cells. Use Professional Growing Mixes from Fafard, Premier Horticulture, SunGro, Berger, etc. These can usually be purchased at a local greenhouse or a greenhouse supply company (BFG, Carlin Sales, Nolt's Produce Supplies, etc.)

- DO NOT over water. Wait until the top of growing media is showing signs of drying out. Then water until it runs out the bottom of the tray. Spot check by lifting up a tray after you water so you know how heavy a flat is when it is properly wet. You will then be able to do a lift test to determine how dry or wet your flats are. This is very useful in the event you do have algae grow on the top of the media (Algae makes it look wet even when the grow media underneath is bone dry).

[jmsieglaff]

Just reading this fairly old thread. I by necessity or maybe convenience do this to my tomatoes. I sow seeds and germinate atop my fridge probably in the upper 60s/near 70. As soon as they sprout they go under the lights in the basement in the upper 50s/lower 60s depending on the year. They get potted up into 4" squares then moved outside in the cold frame between April 15-25. While in the cold frame they experience a fair amount of 40s but they are receiving ample sunlight. The coldest nights are the ones following cloudy days as the black jugs with water are not warmed those days. My tomatoes are always stocky strong and have good roots. The plants always do well. I haven't ever not done it this way but I'm not looking to change a process that works. So call me a fan.

[Labradors2]

How long do your seedlings stay under the lights?

My growlights are in the basement with temps like yours, but I have been putting the seedlings upstairs on sunny windowsill during the day and giving them 4 hours under the lights + 8 hours in the cold/dark.

The resulting seedlings are robust and healthy, but not as stout as the ones that I see for sale in the nurseries in the early summer.

Linda

Originally Posted by jmsieglaff

Just reading this fairly old thread. I by necessity or maybe convenience do this to my tomatoes. I sow seeds and germinate atop my fridge probably in the upper 60s/near 70. As soon as they sprout they go under the lights in the basement in the upper 50s/lower 60s depending on the year. They get potted up into 4" squares then moved outside in the cold frame between April 15-25. While in the cold frame they experience a fair amount of 40s but they are receiving ample sunlight. The coldest nights are the ones following cloudy days as the black jugs with water are not warmed those days. My tomatoes are always stocky strong and have good roots. The plants always do well. I haven't ever not done it this way but I'm not looking to change a process that works. So call me a fan.

[jmsieglaff]

I have the lights just a couple inches above the plants. I turn the lights on ~6-7am and off ~8-9pm, so that's 13-15 hours a day. Sometimes I'll bring the flats up by our south facing patio door during the day when I'm getting ready to move them into the cold frame for a couple days, I don't know if that's necessary, I just don't want them to get sunburn when making the move to the cold frame.

[jmsieglaff]

We had a warm period during the last week the tomatoes were in the cold frame this past year and got a little taller than I wanted--but that really didn't have anything to do with the grow light setup. I just planted them deep.

This is what my tomatoes looked like after being in the cold frame for a few days last year (very cool cloudy days and hence cool nights) pretty much the same size as when them moved out there:
http://www.tomatoville.com/showpost....33&postcount=1

And then 10 days later:
http://www.tomatoville.com/showpost....66&postcount=5

[Labradors2]

Your seedlings look fantastic! I have cold frames, so maybe I could try putting the seedlings in them when spring rolls around. My main fear is scorching the poor things!

Linda

[jmsieglaff]

Thanks! My cold frame autovents so I don't have to worry about that. I bought it about 4 years ago for maybe $100. I've been happy with it.

[Labradors2]

Sounds like a great idea. *I* am the autovent for our cold frames (which hubby built last year). It was a bit late by the time they were finished, so I planted lettuce in them and they were very successful!