Bottom watering
 

I start my seedlings in 3" square pots, and have accumulated various trays to hold a dozen or more pots which fit under my grow lights.

I have always watered from the top because I cannot figure out how to bottom water without the threat of perhaps over-watering and then having to remove all the pots from the tray to drain it.

The problem with this is that it is a right royal pain to have to raise and lower the grow lights every day.

I recently bought some sturdy 10/20 trays from Lowes which should fit, and I'd love to learn how to bottom water.

Any suggestions gratefully received.

Linda

Put holes in the bottom of the pot, I use a soldering iron but you could use an ice pick it something heated on a gas stove
This helps prevent cracking.
Or you could buy cells that are already open at the bottom.
When you start seedlings, add potting soil to the top and press down with your thumb.
Plant seedlings and top with a bit more mix, press slightly.
Fill a small tray about 1" water and set the planters in the Potting mix until they soak up water, move to your permanent tray and water the tray as needed

Make sure you moistened your potting mix prior to filling up your cells.
The water will wick up from the bottom.
Place a fan that will blow lightly across the plants to study them up and prevent damping off.

Yes, using a fan really works well. A friend who has grown peppers for years was amazed at how thick the stems on my peppers are, only due to using a tiny fan.

Bottom watering can be a bit tricky if the sizes of the plants are mixed. I often have to take a pot out to water it individually when the whole flat does not need watering.

Thanks Squibb. I know the basics, and my pots have holes in the bottom and potting soil is moistened well before planting, it's just the concept of bottom watering that I find difficult which is why I've always individually watered everything from the top.

Thanks Growing Coastal. I can see that different sized plants would also be tricky. I really should use a fan too!

Linda

I have always watered from the top and have never had any plants damping off. I start my plants in a sunroom where the air temperature is about 73° rather than in a cooler area like a basement like some people use.

I also use a sterile soiless mix and brand new cell packs since I only grow 2 trays of seedlings and the cells are only $99 for a whole tray.

Fungal spores (like the ones that cause damping off) love cool and damp and they can be introduced by fungus gnats, used pots or garden soil and they will thrive in cool, moist conditions whether you water from the bottom or the top. I try to avoid all of these possible routes of transmission.

Additionally, if you are bottom watering and the water is shared by all of your pots then you could also be spreading the spores if they are present on some of the pots. They will float to the uninfected pots.

I put my plants in web bottomed trays. I now use soil blocks, but I used to use 3.5" pots, but still put them in web trays, which then go into solid trays as long as dripping is a problem. (I start many of my things in the house.) then I found rabbit hutch bottoms at Tractor Supply, which hold two trays nicely with room to spare. I put an inch or so water in those, and rotate my trays needing water through them. Last year I ordered large shallow trays from Greenhouse Megastore which hold four 1020 trays which speeds up watering. I also experimented with using microfiber mats in the trays for improved wicking. It sped watering up by allowing me to dump a measured amount of water into the large trays, and I didn't have to keep moving the trays around. I just got enough large trays to hold most of my 1020 trays, and left them in the large trays with the bottoms lined with the microfiber mats. But again, that's with the soil blocks I now use almost exclusively.

Thanks FarmerShawn! The web bottomed trays sound like the perfect solution to my concern about having to drain the 1020 trays if I over-water, and I will look out for the microfiber mats too.

I started my seeds today (on damp paper towel) :).

Linda

I also top water, figure that overwatering is a bigger risk with bottom water. Also it's messy/splashy at least the way I've seen it done at the farm. :) Not ideal for indoors, for me the wobbly waiter.



Linda I got a little watering can from Dollarama which is great. It has a long spout and I can water everything individually without raising the lights.
I have had the lights down so far I couldn't get in, when I do that I have to make a space and move the tray out to water then put it back. That is, instead of raising the lights which would be much more of a hassle for me.

I have always tried to do all watering from the bottom once I have plants. It makes the plants increase root systems to reach down to the water. If you leave a seedling in the flat and then later check below, you'll see that the plant has sent out a "tap root" to find and retrieve the water in the bottom of the tray. Also, during transplant, I always bury the seedling as deep as I can to make sure the exposed stem can become more of the root system.

The root system is the key to healthy plants that can stand some of our shenanigan's and mis-steps. Work hard on the root system needs and the rest will be a walk in the garden.

Linda, I have to rotate my trays anyway, because the outside row of seedlings in my set up gets less light than the inner rows. So when I pull out my tray to reverse it, half of it comes out from under the lights and can be watered. Then I shove that to the new position and pull out the dry side and water that and replace under the lights. I've never cared for bottom watering either. I also use a fan after most of the seedlings are up.

I do agree with Ted. However, I think location has more to do with how we do things. The lighting and where you are starting plants at inside your house, greenhouse, basement... makes a difference. A fan is important, but that too comes into that grey area. Does your outdoor planting area receive light winds? Mine receives heavy winds - so
I have to get the plants ready for heavy winds of 30 mph/48 kmh +, and then give the plants help with cages or whatever is needed.

You are at the point of starting seeds - my advice is to get them ready along the way to your final growing conditions.

[QUOTE=bower;729937]I also top water, figure that overwatering is a bigger risk with bottom water. Also it's messy/splashy at least the way I've seen it done at the farm. :) Not ideal for indoors, for me the wobbly waiter.



Linda I got a little watering can from Dollarama which is great. It has a long spout and I can water everything individually without raising the lights.
I have had the lights down so far I couldn't get in, when I do that I have to make a space and move the tray out to water then put it back. That is, instead of raising the lights which would be much more of a hassle for me.[/QUOTE]

Sounds as if we are in the same boat Bower! I bought one of those Dollar Store plastic watering cans in the shape of an elephant with a think curly trunk. It can be a bit tricky to use, but what's a little water on the basement floor ;)

Linda

I'm so interested to hear that others top water too, as I thought I must be in the minority for sticking to that. I'm going to try bottom watering this season to see if I can manage it.

Robert, I have heard that putting a fan on the seedlings gives sturdier stems - always a good thing! Failing that, just running your hand over them whenever you can also helps ;).

Linda

I just watered my seedlings and I like to see how much water is added to each pot. Some say that bottom watering encourages deeper roots and I understand the theory. It makes sense but my seedlings always have roots coming out the bottoms of the pots when they are ready to transplant so I am not going to change my methods. I don't really like the idea of water sitting in the bottom of the trays.

It may be different with hundreds of seedlings but I only have 2 trays and I water them every day. Sliding the trays out also shakes the plants a bit. I do not use a fan.

I also slide my trays out from under the lights to water them with a small plastic watering can with a spout. It is the kind that people use for houseplants.

Bottom water only. I want my roots to reach down. Especially once i've potted up.
I'm a slob. But my seedling room is tidy-ish. If it gets chaotic it becomes unmanageable
once I'm off and running come warmer weather with seedlings everywhere.

I am officially in all 1010 trays. Started that a few years ago. No more red cups. I cut all my
1020 small cell trays in half to fit the 1010. Nine 4inch pots fit in a 1010. Sixteen 2and1/2inch
pots.

All my grow lights are fixed. Two 4ft shelves at 8inches to the lights. Two shelves at 16inches.
I just raise my trays. Better use of space. No fussing with chains. All my trays/seedlings are
at different grow heights.

I grow all winter so I need organization. Otherwise is is no longer much fun.
1010 trays I can spin one quarter, or pull it down to check, shake for gnats...check for water.
Right now I have 3 trays going. One is dwarf/micros, one is cherries, one an Artsy dwarf hunt.
A fourth is all salads and greens. (needs potting up). Next 1010 will be indeterminates. 1010's
let me spread out the seeding chore. I can do a flat at the dining table and water in the kitchen
sink being just 10x10 inches. Easy to cary one handed and open a door with the other.
(dropping a 1020 tray after all that work labeling is not funny).

Oakley, thanks for the detailed description! I too have been using trays that are about half the 1020 size. They are sturdy and easy to haul around. I bought them in WM and they don't have smooth bottoms, so no good for bottom watering. The 1020's that I found in Lowes seem to be fairly sturdy, but I will have to be careful not to drop them!

Brownrexx, sounds like my modus operandi, top watering every day, except that when the seedlings are tiny, I water them with a teaspoon, just enough to keep them alive, but not drown them or cause damping off in my chilly basement!

Perhaps bottom watering would be a better idea for me after I have potted up.

Linda

I bottom water as long as my plants are in flats or pots - until I plant them out in containers or earth. I weigh one flat and one pot with completely dry planting mix. Then I weigh the flat or pot with the plant(s) before watering, so I have an objective measure of the moisture level.


Steve

Steve, I was hoping that someone would say something about measuring the water used. I guess I will just have to try different measurements of water for each tray until I can figure out the perfect amount for each watering.

Linda

Watering needs change daily. No real guessing or measuring. For young seedlings
an inch or so tall I just quickly lift the front edge of each tray in the morning. They get
thirsty at the first sign of true leaves.

If any tray feels light I pull it down to my workbench below. Take it out of the 1010
tray a put it in my back burner watering sheet pan. The only things needing water
this morning were the 1010 salad tray and three micro green trays and just one 4inch
pot of a larger dwarf plant. Took all of 5 minutes.

I'll check again tonight. I like to let them dry out. Your own temps and humidity will also
determine water needs. My basement is a bit chilly. But my three trays of larger plants
have been spending the past couple days in a south sunny window. Just one plant of 27
was dry.

[QUOTE=SQWIBB;729914]
Place a fan that will blow lightly across the plants to study them up and prevent damping off.[/QUOTE]

Curious as to how young the seedlings are when you start using the fan and for how long each day do you let it run?

Another vote here for bottom watering. I don't water until tops are dry, then I float the flat in shallow water until the root balls sink. Overwatering root rot is an overgrowth of pythium. It is much worse in cold temps and mucky media. In very hot weather, soaking my container tomatoes and peppers is the only way I can keep them looking healthy.

I think I'm the odd man out, I add water to the trays every day.

24 hours later if they are dry I add more, if there is still water in the pan and depending on how much water... I add more accordingly.

I start the fans the day the seedlings emerge and they run 16 hours a day like the lights.

I know this is an old thread but I'll comment, too.

I always bottom water. My cell packs & pots are in 1020 flats. I try to leave one pot out of the corner of the flat so that I can easily pour water in at that location. With the one pot missing from the corner of the flat and the type of watering bottles I use, I don't need to raise the lights to water. I just pull one tray at a time out from under the lights by a few inches and pour the water into the corner, and put the tray back into place. Since my trays are level, the water will level out and reach all of the pots.

If I don't leave a pot out of the corner, then I just temporarily remove a corner pot, water, and put the pot back in.

For a watering can, I upcycle several large juice bottles that I've rinsed well. After each watering, I refill the containers with tap water, leave the caps off the bottles and let them sit until the next watering time. When it's time to start adding fertilizer, I just add it to the bottles, put the lids on, give them a good shake and remove the lids again.

As far as how much, that's going to depend on how dry the seed starting mix is and how many pots/plants I have in the tray. When learning to gauge how much water, it's better to err less than you think, give the water a chance to soak in, check the soil with your finger and add more if needed. You'll develop an instinct for how much to use over time.

If you get too much water, instead of taking all of the pots out to empty the excess water, it's easy to slightly lift one side of the tray (so the water pools to the other side) and use a plant-dedicated turkey baster where the missing pot is to remove the excess water. Just have a container handy and suction some water out, squirt it in the container, and repeat until you have removed the amount of water that you want to remove.