strawberry winter trials dwc and nft

PupillaCharites(FL 9a)November 12, 2013

I'd like to share my strawberry trial which started with transferring 'Sweet Charlie' strawberries from plugs to a DWC nursery for the young plants.

The idea is to run dual nursery tubs and experiment by making changes in one to get ideas that work better, and as soon as new roots formed, long enough to transfer them into an NFT rig.

DWC is clearly not a preferred method for strawberries and this so far has re-enforced that in a practical way for me. If you can put them directly in an NFT, great! The goal to start NFT is to get the original dirt grown roots from the plugs to reach the channel, and some people cut the disks out of the net pot bottoms and pop them in that way. Others raise the level in the channel with dams for a temporary sort of RDWC in the channels until the dams are removed. I didn't want to do either, but both approaches have issues to deal with.

Whenever I come across a problem I thought I'd share it here in case someone else can benefit since I have appreciated comments from other kind members here which were very helpful.

On September 18 I got my plugs, 49 in all. They were supposed to be pathogen free, but that was not the case. Two fungus types can be noticed on the leaves, though they are strong plants and the pathogens are not obvious in the euphoria of getting live plants of your favorite variety even if they are flattened and somewhat smashed;-). We'll meet both fungi later though.

Due to incessant rains and not being able to get outside, I had to hold the plugs for 3 weeks before transplanting into the nurseries. During that time, I mistreated them by drying them out too much due to inattention and then when outside in the rain to stay acclimatized, they were too humid in a cycle that alternated in extremes with the humidity. They just about used up all the room and fertilizer in their flat and three died by drying out beyond recovery.

Finally they could get the earth removed and be put into 2" net pots with hydroton as the support medium. I chose two inches because it was Grizzman's favorite size and he gets many plants to work in it. Strawberries develop huge root systems when florishing and 3" or 3.5 inches is much more commonly used.

9 days after transplant, they hit their best point. The nutrient formulation was completely custom made and I started them on a 50% EC of my recipe.

pH was maintained somewhat acidic, at about 5.8. The thought was as the very dense planting (about 23 per res - lots of plants and a relatively weak solution), the pH would rise and I wouldn't have to adjust it for a while setting my adjustment only if pH hit 5.6 or 6.9. The plants continued to look stronger for a few days after the above picture, but hadn't moved from pH 5.8.

Within a week a lot of drizzle fell causing initial fungal contamination of a few of the healthy leaves. It was time for a res change which was done on #2 (left side) first. The first test was planned, to keep the formula the same but replace some sulfur with silicon at 12 ppm for that element.

The result was a second variable into this res during this change of 10/25: a careless preparation of the water by skipping a reasonable period of time for dechlorination.

Strawberries are extra sensitive to root damage from chlorinated water. Here is a 50/50 mixture of rain water with chlorinated municipal water (my town uses sodium hypochlorite, i.e., normal household bleach) and the free chlorine concentration is about 0.8 ppm, making this 50/50 dilution under 0.4 ppm of 'chlorination'.

It only sat about 2 hours in the afternoon before the plants started swimming in it, and the reaction was immediate, vigorous plants to the last man and girl quickly wilted and look suddenly like the poop was beat from them in res #2.

#2 was dealt a setback of approximately one month, due to the chlorination. The plants fell back to worse than they were upon transplant negating the excellent growth for three weeks and they did not pick up growing for about 10 days.

The picture is comparing two reservoirs of identical setups, about two weeks after the deed was done. The upper picture was has the insufficiently de-chlorinated water, and the lower water that sat out three days, covered at night and during the day sometimes with new Saran wrap (PE) and stirred once in a while. During the time the sunlight radiated directly in, I uncovered it and mixed it up a bit.

If you have a spare pump or airstone, this is a good time to use it, principaly working better when the sunlight is penetrating. Only 1/16 of the effective UV solar radiation penetrates to the bottom of of 2 foot deep res.

It is principally the sunlight that accelerates the speed at which chlorine is deactivated, and a temperature ramp helps, in addition to 'solarizing' it: for every 10 degrees F it warms, the available chlorine neutralizes itself about twice as fast. This is not the same reaction rate rule of thumb in chemistry - that's a doubling for 10 degrees Centigrade, but in the case it is twice that rate (quadruples for 10 C increase). Two days at 70 F is fine, even if one is somewhat overcast.

Meanwhile in res #1, I decided to leave the nutrient solution (16.3 gallons per res) for a full month since they were doing great so far and I wanted to prepare the water with time. At this point both reservoirs were attacked by a few individual Southern Armyworms (Spodoptera eridania).

Whether I plant peas or strawberries, this is the number one foliage pest by a lot, an incredibly wide spectrum of veggies host it, in this area and throughout a lot of the South. Other similar relatives are the Fall Armyworm -has for black dots on one end on upper back) and Beet Armyworm --usually a more light green which stays on the belly and gets a black back as it matures.

If you don't get it quickly, it decimates leaves, especially young and newly emerging growth. Plus, it provides fungi perfect places to spawn on the attacked leaves.

The armyworms are one reason it is hard to get motivated to put anything tender outside to grow!

This post was edited by PupillaCharites on Tue, Nov 12, 13 at 22:35

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I just started strawberries from clippings, by pressing them into Oasis blocks and pushing them a little deeper into the NFT channel. So far, so good... they look pretty well.

    Bookmark   November 16, 2013 at 6:33AM
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PupillaCharites(FL 9a)

That's a fine idea that can be adapted to the transplant problem of roots not yet reaching the channel bottom. Instead of bringing the roots to the channel by cutting pots, or damming up the channel to raise the water level, or teasing out in a separate nursery hydro setup like me, bring the channel to the roots with a wick like an oasis foam or rock wool and set the bottom of the pot on it ... assuming you want your plants in net pots. sweet!

This post was edited by PupillaCharites on Sat, Nov 16, 13 at 16:57

    Bookmark   November 16, 2013 at 4:39PM
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PupillaCharites(FL 9a)

Ok, earlier on I mentioned the plugs were received with two fungi even though they were from a commercial greenhouse supplier. Here is the first one.

It is called Phomopsis Leaf Blight. My 'Sweet Charlie' strawberry variety is somewhat susceptible to it, unfortunately.

The bad thing about Phomopsis obscurans, the scientific name of the fungus, is that it also attacks strawberry fruits when it's called Phomopsis Fruit Rot which reminds me of a leprosy for strawberries. It is often seen on the strawberries in Walmart here especially as they mummify so I must be careful to keep the hydro strawberry plants far from the mulch pile. Not so easy with all this wind.

Hopefully I can keep it in check. Phomopsis Leaf Blight's signature 'look' on the leaves is a "V" shape with the point starting near the center leaf vein and opening to yellow on the outer portions and dead leaf tissue inside its zone of attack.

This post was edited by PupillaCharites on Tue, Nov 19, 13 at 1:11

    Bookmark   November 19, 2013 at 1:08AM
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Most of your roots won't grow in the net pot. That is why you don't need anything larger than 2".

When I grew strawberries, I dammed the ends of my NFT channels. It was a nightmare. it didn't help that I let so much light strike my nutrient. I had massive silky long strands of algae everywhere. They'd even clog my pumps. The plants grew well until something ate them. I think I got one berry out of 25 plants.
If I were to do it again, I would either start the plants in a shallow DWC system to get the roots out the bottom then transplant directly into the NFT troughs. I won't dam the troughs ever again. More likely, though, I would plant them in an EnF bed. make it about 4" deep full of lava rock. place a styrofoam lid over it all then cut holes for the plants. that will hold moisture a lot better and the plants will be happier. This was working wonderfully for me with some soybeans until the deer caught wind of the free buffet.

    Bookmark   November 19, 2013 at 11:27AM
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PupillaCharites(FL 9a)

Thanks for the commentary Grizz - please feel invited to share your thoughts or experiences in this thread more.

Grizz adds on to two important points. First, the reason I did not want to dam the channels --as mentioned earlier, all these teasing out of root ideas have drawbacks-- was for the suspicion I had that the system would overload with algae. I am a low microbe/algae stickler and the system will be new when it is done. The last thing I wanted was to start off with the problem of algae gobs. I want to say I am pleased I went with the 2" net pots considering the goal is an NFT system with these strawberry plants. In NFT supposedly no support medium is needed and some crops are routinely just stuck in bare stemmed in holes, centered by a plastic cap so they point up and don't fall in. Our use of net pots is actually an NFT-medium hybrid. The 'original' NFT envisioned no net pots.

Now, there are systems in which damming would be a more effective choice. For example if you had a closed system (to prevent light from propagating algae), such as a zig-zag PVC pipe and elbow construction.

IMO, the difference of 3 1/2" recommendations between some DWC systems and the 2" here does follow some logic. The problem with DWC for strawberries is that strawberry roots get waterlogged too easily in my experience. Sooner or later, usually sooner, the system goes downhill for that reason. They develop large roots if you keep going which make the flow of oxygen inside very difficult, and they are prime candidates for rot.

A larger pot filled with say perlite/vermiculite as a mixture will be much more successful of a model to simulate - it is how some commercial systems work - in a DWC system, though hydroton or lava rock would be likely fine too and are easy to manage - because it relieves this problem and converts the DWC to a somewhat above solution "bag" type hydroponic system in that it is actually the medium where most of the action is at and the roots fill out comfortably. So if you want to do DWC I would recommend against small pots.

If your are doing NFT, EnF, Vertical drip, though, that logic no longer is the case and the small pots Grizz uses as well as this system as he says, make little difference to success.

So, I need to get my plants out of the DWC and into an NFT or they will succumb to root rot and oxygen poor water soon. You could blow more bubbles in there, but strawberry roots when healthy *really* grow into massive mats. Not only that, I currently have a plant density that is through the roof. There are about 43 plants in 0.54 square meters in the combined nursery tubs. That is about 80 plants per square meter. The best practices is about 8 plants per square meter!

The needed Sunlight is not getting to them and the roots thankfully are growing. They have outgrown their cribs and how! If I don't watch it, the growing mass will collapse the tub covers on the healthier reservoir that did not suffer the chlorine damage to the roots since they have grown much, much more than the recovering bunch.

This post was edited by PupillaCharites on Tue, Nov 19, 13 at 14:17

    Bookmark   November 19, 2013 at 2:10PM
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PupillaCharites(FL 9a)

OK, now here's the second fungus that was on my plugs. It's name is a real mouthful so common strawberry Leaf Spot is easier. The scientific name is Mycosphaerella fragariae, and it likes strawberries so much that it is named after the genus of strawberries: Fragaria.

I blame more the humidity/drizzle early on and unfortunately never drying up so far more than a few days at a time before another weekof dreariness, and depriving the plants of the needed fall sunlight to grow big and strong vegetation.

Anyway, it starts out as a pretty purple dot, and expands to the size of buckshot, but usually never getting to the diameter of a marble. The inside purple center gets yellow-orangish as the colony progresses and can cause the dying tissue to usually get wet and turn into a hole as it washes (or blows) out.

This stuff is spread in drizzle and wind, and if you have other injuries on leaves, the spores go right in.

Common leaf spot also can attack the strawberry fruits, when it's called "Black-Seed Disease" because it encircles seeds in a hard tar-like color and texture. The seed stuctures are easy access entry points and also the tissue supporting them immediately below seem to form chamber-like compartments like in a submarine so flooding can be controlled. But unless you are selling them,the damage is usually superficial and can be cut off without a problem.

    Bookmark   November 20, 2013 at 5:57PM
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I heat my greenhouse in the middle in of winter in Wisconsin with a natural gas heater. Watch my video

    Bookmark   November 21, 2013 at 10:47AM
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PupillaCharites(FL 9a)

Armyworm caterpillars try to make a comeback, but to the rescue pitter patters a friendly lizard for a continuous security patrol so I don't have to.

I'm guessing s/he's a juvenile Anolis carolinensis seminolus, the Florida variety of the Carolina Green Anole, which species ranges as far up as Texas, Virginia, and Tennessee, but he may be the type species. If I got it right these guys are in danger by encroachment from the huskier Cuban Anoles, invasives, which also have happened by but seem to play marbles with hydroton.

I don't think he'll want to eat flowers but for the moment he has a red-carpet welcome and seems to enjoy being around hydroponic strawberry plants and will fight for his place in the next Biosphere! Can't say enough about being attentive to pest problems. Everything can be just great but some of the plants have been attacked and are now marginal rather than strong due to the loss from preditors eating leaves and it snowballs when fungal infection follows and thiose plants get pushed over the edge. So far there are 42 plants remaining of the original 49 but really only about 4 were lost for this reason, and about two are pending and probably should be removed for the safety of the rest. I haven't seen much in the way of mites. But there has been a healthy crew of miniature wingged insects that look to be patrolling for micropests as well which may explain getting this far.

The best natural pest control I could ask for, lucky, and he has a partner or two.

This post was edited by PupillaCharites on Thu, Nov 21, 13 at 18:27

    Bookmark   November 21, 2013 at 5:59PM
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PupillaCharites(FL 9a)

Now, I wanted to talk about temperature for the Strawberry Winter Trials. It is something I thought a lot about before deciding I had a chance. The question was basically,

"How far north can we go and successfully have an expectation of reasonable production of strawberries in an outdoor hydroponic system?"

But that became more complicated than just drawing USDA zone lines, and I settled for, Will it work on coastal NE FL?

To answer that, first had to understand the needs of strawberry plants... Generally it is 50 F - 80 F, with cool nights being ok...but what happens if the res gets near freezing?

Nope, no problem a heater wouldn't solve in the reservoir. The problem is keeping enough photosynthesis going.

There is a commercial strawberry industry in Florida, which is centered on Plant City, southern zone 9b and even spilling into zone 10. I'm barely 9a and can ride a bicycle to zone 8b at my leisure. So - I thought better just compare what the commercial industry has with what's here:

The result: They are several degrees warmer for their average mid winter temperatures, but if I look at their records, we have a lower variability, actually when looking at record lows, we haven't gotten as low. That's good. The only significant risk was actually the average highs from the end of December to the first week of February. They run about 8-10 degrees warmer, 62 vs. 72 F or so. Now I can see where they get that spurt of winter growth to beat out the California crop - an Ah Ha! moment, since California is generally milder, but at a higher latitude. It fits together. So the question will be whether my mid Dec to mid Jan temperatures is warm enough to keep it going, and maybe I'll just be delayed a month in sync with California (and Maybe I should have chosen the 'Chandler' variety). This is a good bet though - since their extreme temperatures fall reasonably within my weather. But Brunswick Georgia is about as far as I would be enthusiastic.

Yes. I should have chosen 'Chandler'. However, 'Sweet Charlie' is a proud Gator (Univ. FL) may have some ability to resist Florida pests and humidity, unlike 'Chandler' which is a California variety, and possibly the most succulent.

Here is the temperature profile comparing prime 'Chandler' country in Saticoy, CA vs. NE FL, with the same color scheme as the previous graph where Saticoy's data and colors replace Plant City, FL. You can see where that California mildness comes in, but my area is closer to Saticoy through the early Spring than it is to Plant City Florida. NE FL and Saticoy lows are similar and Saticoy is right between Plant City and NE FL, if not somewhat closer to NE FL regarding the average daily highs through the crucial January stretch for the Valentine's Day strawberry race. However, cloud behaving, NE FL gets more vital Sun than Saticoy, and NE FL has a better December to make Saticoy its (our) winter/early spring California counterpart and competitor if there could be one:

By June, you can see our average highs go towards 90 F while Saticoy's stick around 80 F for the Summer. That's why they can have nearly year round production, and we can't as the pathogens go wild and the plants can't hold up well at those temperatures and humidity.

In Florida strawberries are treated as annuals and planted around October 1 in general, and finish off around June. These are generally short-day varieties to insure genetics for enough Sun to support fruiting. Other types of strawberries require long day length. The whole reason the Florida industry is competitive is due to getting berries out one month earlier before Valentine’s Day, before California is fully online.

Unfortunately for Florida, imported Mexican Strawberries from places like Michoacan are starting to spoil the tiny window of opportunity, thanks to stores like Walmart’s shrewd encouragement, Florida's 10,000 strawberry farmed acres fell for the first time last year after being a poster child of modern farming success and has a gloomy projection. Meanwhile, in the last 15 years, Michoacan has essentially gone from nothing exported to offer to increasing acreage to over 10,000 acres as Walmart and multinationals like Dole effectively make the future of Florida strawberries as a commercially viabile employment less and less possible. The benefits are cheaper strawberries optimized less for taste, but for long distance shipping and pretty much are tending to relegate Florida Strawberries to U-Pick and farmers' market operations plus home gardeners. Regulations and government subsidies are widely recognized as grossly unfair against US growers, compared with ever increasing strict US regulations. If only breeders would focus on hydroponic traits in selections, this clearly losing paradigm might be shifted back into the US's favor in some areas, as strawberries is a high value crop that has always been on the edge of possibly going hydroponic. Instead, The best shipping resistant US commercial cultivars principally developed by the Univ of FL (especially 'Strawberry Festival', named for the Plant City Strawberry Festival and commonly called 'Festival') an to a lesser extent Univ of CA (for example, 'Camarosa') and are both adapted well to Michoacan, Guanajuato and Baja California, led by contracts, paybacks and subsidies among governments, drug cartels (Michoacan's economy is dominated by the cartels and nothing can be done withiout approval) and the following multinational catalyst players: Driscoll's, Green Giant, and Dole Foods to follow the Walmart business model using the Sinaloa tomato model. Hopefully this explains why strawberries 'don't taste as good as they used to' and why hydroponics might become a more saving niche and local opportunity, if breeders only changed their mindset (they won't, since our state ag instuitutions receive a couple cents royalties to supply the farmers using conventional growing methods, including from Mexico - simply there are no champions of the hydroponic's cause and farmer's have little leverage when it comes to international trade and the politics of the ag departments of their local tax dollars built).

Absent that, recalling the perfect temperature for growing strawberries is a high in the 70's (F) and a low in the upper 40's (F) to 50's (F), as Mexico catches on, I have no doubt that the Florida Strawberry industry and its 12,500 jobs will be out of business over the next 10 years, thanks in part to enterprising Mexicans that made liberal use of UF and UC professors earning "consulting fees" on the side with Mexican vacations helping transfer farm technology in a strawberry wonderland at perfect year round temperatures that slaughters US weather year round at all but the very best months. Part of the Mexican growing systems utilize hydroponic fertilizers for fertigation. I mention this only to show how enterprising farmers can utilize some hydroponic methods and breeding programs set up by state institutions and cannibalize the agricultural interests that established them in the fiorst place. Also, because an unstated goal of the trial was to learn enough to see whether I could start a profitable business growing strawberries. That was a no-brainer - the answer is it isn't worth doing except for a U-Pick farm to sell local high end, high risk crops.

BTW, average rainfall in Michoacan is less than 1" monthly (less loss to fungi and bacteria - preferred by strawberries) and solar exposure is always more in Mexico than in California and all the Florida growing months, and intensive picking labor is much cheaper and essentially unregulated.

OK, back to the trial, but that was an important topic for my trial, now it will just be for a hobby and I'll leave the up and coming strawberry mongels to the Mexicans, They'll have double the Florida acreage in just the state of Michoacan alone in the next two years and likely continue exporting 98% of it, swamping completely Florida's winter crop which in recent years has been the exclusive provider of strawberries for US consumption representing 15% of American strawberries.

I also checked the Solar energy maps from the Department of Energy. While the story on average was not great, the consolation was that some winters have been worse in historical data from Plant City vs. NE FL, I assume due to cloud cover, but at the threshold the 25% more energy they get is difficult to compete with.

Final assessment. Yes. Get the earliest producer possible, and plant 2 weeks earlier. That's part of the reason I chose 'Sweet Charlie' which was patented based on three things: Super early heavy production, high brix, and the first strawberry developed for Florida that had Anthracnose (Colletotrichum acutatum) Fruit and Crown Rot resistance. I hope not to be posting examples of this fungus. which is even worse than it sounds!

This post was edited by PupillaCharites on Sun, Nov 24, 13 at 12:45

    Bookmark   November 22, 2013 at 11:26PM
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PupillaCharites(FL 9a)

I let this thread go since it started getting big and had my hands full. I still haven't gotten my strawberries out of the nursery since I lost my Mom. It is a very special project because she was not well and I promised her she could eat flavorful strawberries unlike the stuff in the stores. An hour after I harvested the first two that were to go in her special food that evening, I lost her. It is hard to eat these strawberries now. We had our temperature drop 45 degrees from nearly 80F to 32F this morning and most were harvested as a little precaution, just too delicious for me to eat. I planned to run a blog on it as a more appropriate format, completely non-commercial at but it may take a while to get back into it since at the moment I am just keeping the two nurseries healthy.

    Bookmark   January 3, 2014 at 1:40PM
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