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barcus
04-23-2010, 05:22 PM
Aloha from Hawaii. I am on the Big Island and started an aquaponic system last Nov. There is only one problem and that is the lettuce is all bitter. Some say heat, I say nay. I grew up in Iowa where it is 90-100 in summer and never had bitter lettuce. Some say it is growing too slow. I was wondering if a lack of potassium would do it. In checking water this is the only thing not showing up. What do you guys think?

urbanrunoff
04-23-2010, 07:56 PM
yeah mine was a tad bitter too, maybe because it grew slower because of my f#$%$#% high PH

badflash
04-24-2010, 05:56 PM
It is caused by heat. Heat triggers lettuce to go to seed. When that happens it generates a bitter alkaloid, sort of a natural bug poison so the seeds can mature. Lettuce is a cool weather only crop.

jackalope
04-25-2010, 08:20 PM
Have you tried thick seeding and harvesting very early so as to get micro greens?

Although i live in a very temperate area (sun diego, ca) i always make sure to buy loose leaf, slow bolt varieties, harvest early and replant often. For me, heading lettuce is just a waste of time. Loose leaf is more reliable, faster and easier.
Good to know, thanks .... now if I can just get mine to get past the sprout stage this year .........

mommyhen42
01-09-2011, 10:49 AM
I have found that too strong of light will also make it bitter as well as inadequate nutrients.

I grow most of my lettuce indoors year round and have not had problems with that system, but the system is 3 years old now and well aged.

Inside the greenhouse I had to overload things for a while to get the correct amount of nutrients in the gravel, the introduction of a pound of redworms to each tub helped out a lot too!

We are iron defficient here so I have a couple of horseshoes in the tilapia tank

urbanfarmer
04-18-2011, 11:12 AM
High temperatures (above 85 F) can lead to bitter tasting lettuce.
http://edis.ifas.ufl.edu/cv247

Information with numbers from the University of Florida Institute of Food and Agricultural Sciences extension are based on scientific research. I hope this settles the matter! :mrgreen:

rfeiller
04-18-2011, 11:38 AM
I believe both heat and bolting cause bitterness. As soon as the winter lettuce in my greenhouse started to bolt the lettuce became bitter. The greenhouse never hit 80 usually in the 60's. I don't plant lettuce in the summer here because it is always bitter. Near the coast where it seldom gets above 70 lettuce is grown year round

swamp creek farms
04-21-2011, 06:43 AM
I read in a book yesterday to put the bitter lettuce in the fridge for a couple days, lets it relax or something. Have not tried it

davidstcldfl
04-21-2011, 07:34 AM
I believe both heat and bolting cause bitterness.
Me too. They seem to go hand and hand..it seems to bolt when it's hot, and at the same time, it's obvious it's getting bitter.


I read in a book yesterday to put the bitter lettuce in the fridge for a couple days, lets it relax or something.
Hmmm.?...now that's interesting. Might have to try that. :)

urbanfarmer
04-21-2011, 09:52 AM
To be technically accurate: heat without bolting will cause bitter lettuce, bolting will cause bitter lettuce, heat will cause bolting will cause bitter lettuce. The exact numbers are VERY specific to cultivars.

UF Research Study: Lettuce Cultivars for Warm Season 99-13 (http://nfrec.ifas.ufl.edu/files/pdf/publications/SVReports/crop/lettuce/99-13.pdf)

> Common name: lettuce.
> Latin name: Lactuca sativa L.
> Family name: Compositae (Asteraceae)
> The Latin name (Lactuca) is derived from the Latin root word "lac" or milk.
> "Lettuce" derived from the French "laitue" meaning "milk".
> "Sativa" means grown from seed.

Bitterness associated with the production of latex, the milky juice still found in the cultivated varieties when they flower.

http://www.hort.purdue.edu/rhodcv/hort4 ... e00001.htm (http://www.hort.purdue.edu/rhodcv/hort410/lettuc/le00001.htm)

http://www.hort.purdue.edu/rhodcv/hort410/lettuc/milk.jpg

Also, from our Master Gardener's in AZ: Lettuce withstands light frost; however, sunlight and high summer temperatures usually cause seedstalk formation (bolting) and bitter flavor.

http://ag.arizona.edu/pubs/garden/mg/ve ... ttuce.html (http://ag.arizona.edu/pubs/garden/mg/vegetable/lettuce.html)

and a fun fact...

What is the best time of the day to harvest lettuce?

A. Research has shown that lettuce harvested at 7 a.m. contains up to 100% more sugar than leaves picked at 2 p.m.

http://www.ag.ndsu.edu/hort/info/vegetables/tips.htm

rfeiller
04-21-2011, 12:44 PM
Good info urbangardner.
Didn't know about resting iti in the fridge. The turtles enjoyed most of it :D

davidstcldfl
04-21-2011, 12:59 PM
What is the best time of the day to harvest lettuce?

A. Research has shown that lettuce harvested at 7 a.m. contains up to 100% more sugar than leaves picked at 2 p.m.
The early bird gets the sugar fix.... :P
Do you think that applys to most veggie plants...?

urbanfarmer
04-21-2011, 02:30 PM
What is the best time of the day to harvest lettuce?

A. Research has shown that lettuce harvested at 7 a.m. contains up to 100% more sugar than leaves picked at 2 p.m.
The early bird gets the sugar fix.... :P
Do you think that applys to most veggie plants...?
I would think so. This happens in leaves; so, any plant where you eat the leaf will probably have a similar situation.

rfeiller
04-21-2011, 02:35 PM
Flowers picked in the early morning last much longer then those picked later in the day.

urbanfarmer
04-21-2011, 02:45 PM
But, do they taste better? :mrgreen:

rfeiller
04-21-2011, 05:05 PM
You bet!! :lol:

davidstcldfl
04-22-2011, 05:08 AM
I've got some lemon gem marigolds started....I'll let you know if the flowers taste better in the morning. Serious....I'm trying them to see if a restaurant wants to use them for their garnishes. They also come in red and orange.
Johnnys seeds has several flowers they 'claim' they are edible....maybe it depends in 'how hungry you are'... :lol:

urbanfarmer
04-22-2011, 01:43 PM
David, there is at least 1 commercial grower that I know of that converted his hydroponic farm of lettuce and the like into edible flowers. He sells exclusively to restaurants in Georgia and is making a KILLING off the profits. If I run into those folks again I will try to ask more about it, but that's something you might want to look into if that's what you are trying to do!

davidstcldfl
04-22-2011, 04:48 PM
Cool. Thanks, it would be interesting to hear more.