Pots & drainage

[KirstieSparkle]

Back from my business travels and starting to build up the pots ready to put plants in...
People have said about making sure to put drainage holes in.
Do ALL pots need drainage holes or are some crops better in things without drainage holes?

And errr say you didn't have a drill how would u make them? Is there a best size for drainage holes? Better in big pots to have more than one hole? One bigger hole or lots of little ones?
I know I sound like a noob.... It's coz I am and don't want to mess up on such a tight budget

[Chomerly]

Depending on the material the pot is made from (plastic, clay, ferrous metal) the difficulty could be simple to almost impossible without a good drill and bit.
If the pots are plastic, and that it isn't too thick, you could use a very sharp carpet type blade to cut holes in the bottoms.
the biggest risk with this option is that it can be dangerous if the pot breaks while cutting and the other issue is damaging the pots in general.

Personally, i would just buy a cheap drill with a set of cheap drill bits (both can be had for under £40 depending on where you shop) and use it to create the holes.
Much more efficient, much easier and most importantly, much safer.

[snakeshack]

for plastic pots I use a hot skewer,I think pots tend to drain best if you make the holes in the sides right at the bottom others may differ

[Bill HH]

Plastic pots are easy, get an old screw driver or similar and heat it up with a blow lamp, or your gas ring. Just burn the holes in. avoid breathing the smoke. On big pots I like to have a few holes round the bottom edge as well as the bottom. Clay pots usualy have a hole in anyway but if not you need a drill with a masonry bit and steel pots you need a metal drill bit. With the steel pots its best to start off with a small drill bit and the move up to a larger one (1/2 inch). I would say you allways need drain holes in pots.

[Bill HH]

for plastic pots I use a hot skewer,I think pots tend to drain best if you make the holes in the sides right at the bottom others may differ

Hahaha great minds.

[sparrow100]

And another vote for a hot skewer/srewdriver. I do mine 2 inches up from the bottom so there's a little water reservoir for hot days.

[Potstubsdustbins]

All pots should have some form of drainage unless of course your growing water lilies.

I don't like using drills in plastic it can shatter to easily. if you have a plumber mate ask him for a foot of 15mm copper pipe it heats up much faster than steel but don't forget to wear a leather glove.

Potty

[Bren In Pots]

And another vote for a hot skewer/srewdriver. I do mine 2 inches up from the bottom so there's a little water reservoir for hot days.

I do that with the flower pots I grow my spare toms in, that way they can be left if we go camping for the weekend.

[Bill HH]

Yes copper pipe is perfect and a good size for the hole, dont make tiny holes, at least 15mm, the compost wont fall out.

[AllInContainers]

I tend to drill holes around the side by hand with a sharp awl on a swiss army knife or multitool, but failing that I'd use a drill (no need to mess about with hot pokers and nasty fumes).

It's easy to crack a plastic pot if you get it wrong with a drill, and here's the three best ways of making a mess of it.

• Putting pressure on - Not needed with a new/sharp drill if you use it properly
• Running the drill too slow - People sometimes think that if they go slow it's safer, but with plastic it just means it's more likely to snatch and that'll end in tears. If using a variable speed drill you want it on it's fastest setting, and fully depress the trigger button.
• Stopping the drill before you've taken it back out the pot - This again is likely to cause it to snatch or jam. Get the drill going fast with a new sharp bit, touch the drill on and gently drill the hole, then pull the drill back out of the hole while it's still whipping round at full speed. THEN let it stop. Clear off the raggedy bits of plastic from the drill bit, then move onto the next hole

I drill all the holes towards the bottom (but not ON the bottom), so you DON'T get the reservoir. The reason for this is I want to be able to use my pots for whatever I want in future, and some plants don't like having their roots sat in water. Get the wrong plant in a pot with higher level drainage, and you could end up with roots rotting.

I also put "crocks" in the bottom of my pots to improve the drainage. This can be pebbles, bits of broken clay pot, or bits of polystyrene. Polystyrene makes the pots a lot easier to move if you have to, but there is a downside. Making the pot less heavy means that it's more likely to blow over in the wind. Polystyrene is therefore fine for low plants, but with tall stuff you're better with using something heavy so pebbles, broken bricks or broken clay pots are far better.

I have noticed that some people here say that putting crocks in is a bad idea, as water doesn't transfer readily between substrates. I totally disagree with that philosophy! Once your compost has been watered for a couple of months, it will start washing down into all the nooks and crannies around the crocks. The water flows down through the compost, but at the bottom layer around the crocks, there's less compost to be able to hold the excess fluid and it will flow out. You're not asking the water to go from compost to rubble - you're just thinning the compost out so it can't hold water as well. The only reason it won't flow, is if you have drilled the holes too small and the compost plugs them. THEN you have the change of substrate problem - compost to air. Ensuring your holes are 5mm or bigger should sort this out - and put a hole every 2" to 3" or so around the base - . Worst case scenario if you think your pots are holding water is go round the holes and give them a gentle poke with a nail or screw to dislodge any blockages.

Compost does hold moisture well, and for those plants that need more, you can get pot and basket compost which has water retaining gel in them. Another thing that's good for increasing water retention for thirsty plants is reused compost. After you've grown plants in compost for a year, it's less "airey" and will hold more liquid BUT will have no nutrients. Cure this by mixing in slow release granules.

Some plants prefer a drier mix, so you could mix in a bit of top soil, sharp sand, or horticultural grit depending on the plant - though you'll probably find most plants are fairly happy in new MPC if watered and fed according to their needs.

Have I missed anything?

[KirstieSparkle]

Omg! Ok so put the holes in the sides at the bottom instead of the bottom? And errr try find my pen knife to see if I can manage with that otherwise I'm stuffed as I have a halogen hob and no drill lol

Omg every time I go to start stuff I discover something else I'm missing :-(

[AllInContainers]

Holes on the sides just lets the water out easier if you have the pots sat on a flat surface. Careful with the penkife, that could make a mess of both you and the pot. You'd be better borrowing a drill off a mate if you can

[Veggielot]

From experience definitely go for drill. Knives are great for the right job cuting holes in pots is not one of them. I sliced open my thumb trying to use a knife for the wrong job.

If you go with a drill try using a wood drill on plastic pots I find they work well on plastic.

[Kristen]

I have noticed that some people here say that putting crocks in is a bad idea, as water doesn't transfer readily between substrates. I totally disagree with that philosophy!

Its contrary to what my brain tells me too, but not according to scientists. These are the first of many from Google:

Gardens: Old wives' tales | Life and style | The Guardian

The Myth of Drainage Material in Container Plantings

Container planting: intuition vs. reality | Garden Professors

I still don't know which is right, but I see the scientists says that crocks don't help. I can certainly see that crocks take up space that could contain potting compost ... and that if crocks are no better than no-crocks I would prefer to have more compost instead. But still my brain con't convince me that no crocks drains better.

[starloc]

It is a proven fact that adding things to the bottom of pots causes drainage problems not gives better drainage, thinking that it doesnt make things worse is like saying the world is flat....

It just raises the wettest part of the compost up the pot making it all wetter

I have seen it myself and experts across the world agree about it, no decent/real nurseries ever put things in the bottom of pots either

There is a great article on a page from the university of Florida, about all things container potting media and drainage etc

BUL241/CN004: Growth Media for Container Grown Ornamental Plants

Quote from it> "Some have suggested the placement of gravel in the bottom of containers improves drainage. In fact, the gravel decreases the total volume of medium with favorable aeration. The pores at the interface of the container medium and gravel must be saturated before water will move down into the gravel. This means that a layer of medium with near maximum water content is positioned above the gravel rather than on the container bottom."

A free draining growing mix in the pot is best, with lots of holes in the pot, I make slots up thee sides of pots with a milling cutter in a drill , giving a hole in the bottom and the side of the pot, about 2 inch up the pot about 1cm wide