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I have a large (70L?) moulded plastic pot which is filled with topsoil, and has a freshly planted lilac bush in it. I had noticed this pot did not have drainage holes at the bottom, but had thought that the large volume would allow for a fair amount of water to be locked away in the soil.

I've quickly noticed that I am getting a fair amount of standing water on top of the soil, even after fairly modest watering.

Should I drill drainage holes in the bottom of this pot, or is there another suggestion on how to deal with this situation?

VividD
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Stephen
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3 Answers3

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If it was me, I would most definitely drill some drainage holes in the bottom of that pot.

Standing water will greatly increase the chance of disease developing within the soil...

Standing water also greatly increases the possibility of plant root rot.

I'm sure there is the odd occasion where one might not need drainage holes in a pot, but I have personally never encountered such a circumstance.

Mike Perry
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  • @Stephen - I concur with Mike's view; if water is left to accumulate in the bottom of the pot, this will almost certainly lead to root rot. Drainage holes are indispensable if the plant is to remain healthy. – Mancuniensis Jul 07 '11 at 23:53
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    Along with the root rot, the lower levels of the pot will become anoxic (decay uses all oxygen up) which is not a chemistry you want. Anoxic soil can usually be detected by its sulphurous smell. – winwaed Jul 08 '11 at 02:37
  • @winwaed - Excellent point! – Mancuniensis Jul 08 '11 at 12:12
  • Uni-bit and put in three to five holes depending on the size of the pot. Pottery shards over the tops of the holes with a little gravel to keep dirt from plugging them. Avoid pot rot with proper drainage. – Fiasco Labs Aug 13 '13 at 23:35
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I'm a master gardener, so let me just say for the future (or if you're comfortable transplanting your Lilac) always, always use a clay pot with drainage. If you aren't comfortable trying to transplant your Lilac you need to put in some drainage holes. The plant will not survive without them. Good luck, happy gardening:)

S. Jones
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    Welcome to SE! I'm giving you a +1 to help you get started here. Tell me... why do you recommend clay pots over other materials? – Randy Aug 14 '13 at 00:07
  • The thinner plastic pots seem to degrade in 1-2 seasons and become brittle, then break. If they only made plastic pots out of the same type of plastic used for rigid ponds. That pond plastic seems pretty tough. My plastic food barrels (55g) have been outside for 5+ years and they are also doing fine. – Bulrush Jun 27 '16 at 19:11
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Always drainage. Even semi-aquatic plants - in nature there is water movement through the root systems which introduces oxygen. There's no such thing as too much drainage, just too much drainage for a reasonable watering schedule.

Container material isn't too big of a deal. Clay's advantages are weight (no toppling over in wind), porosity, and sturdiness (roots aren't disturbed when the pot is moved). Take care when moving your plastic pot so it doesn't jostle the roots too much, and don't let the soil dry out (for the obvious "plant needs water" reason but also so it doesn't fall over). Best is fabric, but that's introducing a much greater deal of attention or materials.

I wanted to ask about where you said "topsoil". If you filled your container with actual topsoil, this will be a problem. Topsoil is an amendment for ground or bed gardening, it's not a potting medium. Even when put in the ground, it has to be mixed with either native soil or a host of other ingredients to promote drainage.

My recommendation: Take it out of the pot, drill drainage holes, gently get as much soil off the roots as you can, gently wash off the roots, repot into a potting mix. (Standard Miracle-Gro Potting Mix is fine if you don't want the hassle of making your own.)

Personal note: I love lilacs. I have a 8'x8' patch in one corner of my lot, and six or seven 15'+ tall ones scattered on the wood border. When they bloom my backyard smells ridiculously amazing. AND when they have to come down (had to take down a couple twenty-footers two years ago) they provide incredible wood for small projects - twice as hard as oak and the heartwood is an amazing pink-peach color that contrasts the bone-white sapwood. So - good luck with that plant!

Paul Nardini
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  • Thanks Paul, I drilled those holes 5 years ago and the lilac is still thriving. – Stephen Jun 29 '16 at 15:03
  • You could also just amend the mix in the container. Not gonna lie, I've done this a few times when the mix or packing turned out bad but either just barely bad or for one reason or another I didn't want to repot. 2 semi-easy ways to do this are 1) take out soil from wherever you can and replace with compost/composted pine bark minis/perlite/vermiculite/pelletized diatomaceous earth, 2) bore a cylinder down through the soil to the bottom, stuff it full of any of the same things, cap with a couple inches of what was in the hole. -- Lava rock <1/4" works too. – Paul Nardini Jun 30 '16 at 18:23
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    Oh crap - yeah this was from 2011! lol. I didn't even notice till after I hit "add comment" just now. Was like.. .wait he said "freshly planted"... ---- well, carry on then! – Paul Nardini Jun 30 '16 at 18:24