It's awfully dry here - but is it too soon to water?

[EPPhoneHome]

I feel a little silly asking this, but I am terrified of overwatering (overwatered and killed my first succulent very quickly, still feel bad about it) and want to make sure I'm approaching this correctly.

I have three small cacti (golden barrel, mammillaria microhelia, and echinopsis chamacereus hybrid) in terra cotta pots on my balcony. The soil is a mix of ~40-45% Miracle Gro Cacti/Succulent soil and ~55-60% pumice. I know, I need to get away from the Miracle Gro, but I had bought a lot of it when I first got these, and didn't want it to go to waste/couldn't really afford just to toss it, so I cut it with pumice. I have been watering the cacti only when the soil is completely dry, which was typically every 6-8 days (very occasionally 4 or 5, if it was particularly hot and dry), before I repotted them with the pumice mixture. When I water them, I really soak them, until water runs out of the drainage hole (making sure to empty the saucers under the pot, of course).

However, it has been a very dry, hot summer here - frequently below 20% humidity, almost never higher than 35%, and averaging mid-high 90s daily for weeks now. We're expected to hit 101 later this week. On Friday, I watered the cacti for the first time after repotting. I checked yesterday (Sunday), and the soil was already bone dry. I expected to water more frequently, since this new soil mixture retains less water, but every two days seems like a lot - should I really be watering this frequently (every time the soil completely dries)?

I know this all varies quite a lot based on weather, region, etc., but I just wanted to run it by you folks and get some thoughts before I start watering so frequently.

[Jangaudi]

In general you should wait until the soil is dry, also deep down before watering them, or you would risk rot. This does not mean however that the cacti really need water at this stage, and can easily sit there for days on end without a drop. Every other day really sounds like too frequent, but dry weather, hot weather, and terra cotta pots will consume more of it, so I think your previous rate of every 6-8 days (very occasionally 4 or 5) sounds better Are they starting to shrivel or so ? Are they in full sun ?

[EPPhoneHome]

Thanks so much for your response! This is really helpful.

In general you should wait until the soil is dry, also deep down before watering them, or you would risk rot.

This is the general rule of thumb I've been following - the soil is dry all the way down to the bottom of the pot, as best as I can tell. I've been testing this by inserting a wooden dowel down to the bottom of the pot and checking it for any moisture or damp soil. Not sure if this is an ideal method, but it's been bone dry.

Are they starting to shrivel or so ? Are they in full sun ?

They get 6 hours of full, direct sunlight daily. They're not shriveling, per se, and the golden barrel and mammillaria don't appear to have changed at all. The two echinopsis had developed a bit of a lean before repotting, and they're continuing to do so now. There is a little yellowing at their bases, which had began at least a month before I repotted them. Here are some pictures, for reference:

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[Jangaudi]

they don't look shrivelled, so I'd stick to every 6-8 days (very occasionally 4 or 5) in the growing season. Not sure what the yellowing is, someone else might

[EPPhoneHome]

I'd stick to every 6-8 days (very occasionally 4 or 5) in the growing season.

Okay, awesome! So, just to make sure I'm 100% on the same page: I was watering every 6-8 days (very occasionally 4/5) when the cacti were potted in 100% Miracle Gro. Now they're in (roughly) 50/50 Miracle Gro/pumice - I should follow a similar watering schedule, regardless?

[Jangaudi]

watering every 6-8 days (very occasionally 4/5) in Miracle gro (although I do not know it I assume it's the standard sort of garden center cacti soil) was probably way too often, so now in 50/50 it should at least be acceptable. Most people here grow in grit/pumice rich soil and water less frequent than this, unless we'er talking seedlings and such. I personally stick to every 9 to 12 days, or 7 to 8 days during hot periods...and I haven't had any complaints so far

[EPPhoneHome]

Okay, makes sense. Some additional info: I was watering every 10-14 days during the spring, while it was cooler here - just made sure the soil was completely dry before watering. It's just gotten so hot here recently, which is why I'd upped the watering frequency over the last month or so to every 6-8ish days.

I'll definitely stretch out the time a bit between waterings! Thanks for all your help.

[esp_imaging]

Cacti are generally OK in porous mix with heat plus water, with some exceptions (Pediocactus?); many succulents (winter growing memebs) are not.

If they are in terracotta pots on a hot balcony, with really porous mix, it's actually quite a brutal environment for plants and the roots will dry out far quicker, and far more thoroughly, than they would in all but the most extreme droughts in nature. I'd absolutely soak them periodically, and make sure they stay soaked for (say) 24 hours before allowing them to dry out. Put a very deep saucer underneath them, water them thoroughly and have maybe 1/2 to 1" of water standing in the saucer.
You may find it will all be absorbed over a day or so - meaning that the plant is actually wanting to absorb more water than it has been able with lighter watering.
Things like Chamaecereus hybrids can take a lot of water anyway, in 50% pumice mix they can probably be permanently damp all summer, so long as they don't stay waterlogged.
Quite a few or my cacti are outside in the UK over summer. It seems to rain most days at the moment. So long as they aren't in saucers, or I empty them (daily!), they mostly grow well.

[esp_imaging]

they don't look shrivelled

They don't look fully hydrated

[keith]

Going to dry out fast in Clay pots in a desert climate.

[EPPhoneHome]

If they are in terracotta pots on a hot balcony, with really porous mix, it's actually quite a brutal environment for plants and the roots will dry out far quicker, and far more thoroughly, than they would in all but the most extreme droughts in nature. I'd absolutely soak them periodically, and make sure they stay soaked for (say) 24 hours before allowing them to dry out. Put a very deep saucer underneath them, water them thoroughly and have maybe 1/2 to 1" of water standing in the saucer.

Things like Chamaecereus hybrids can take a lot of water anyway, in 50% pumice mix they can probably be permanently damp all summer, so long as they don't stay waterlogged.

Thanks so much for chiming in here! It's really reassuring to hear that your cacti have been happy taking water so frequently. I have been extremely nervous about overwatering, but I'm trying to keep in mind that I live in a much drier climate than most, so I'll need to water more frequently. We normally have a monsoon season every summer (torrential downpours at least four afternoons a week), but, unfortunately, it looks like it may not come this year, so I may have to compensate... Have you had any issues with leaving them in water overnight? I only ask because I've seen a lot of folks say that will lead to rot, so I had avoided leaving any water in the saucer for any period of time, let alone 24 hours.

Would you suggest watering every time the soil fully dries out? This would be about every two-three days. When I water, I water until there is water flowing out of the drainage hole. Is this what you mean by "soak"? Apologies if that's a silly question, I just want to make sure I'm on the right page!

Thank you again for all your advice!

[esp_imaging]

When I water, I water until there is water flowing out of the drainage hole. Is this what you mean by "soak"?

No, I'm trying to say there is a difference between adding water (even quite a lot of water), and making sure the soil mix is thoroughly wetted.

In a >50% pumice mix, water can just flow through without actually being absorbed by most of the mix. You apply water, it finds a path of low resistance through the mix, and pours out of the bottom without wetting most of the compost. I guess completely dry miracle grow doesn't re-wet easily?

As an experiment, put the pots in bowls and fill the bowls with water to maybe 1/4 the depth of the pot and leave overnight and see how much water is absorbed. See what happens- does the soil get wetted all the way through? I bet it doesn't, it will be barely enough to moisten the bottom of the pot - although it should get the roots there working well.
A further experiment - place the plants in a bucket of water to completely cover the soil mix (or nearly, your pumice will float away!) so the soil is completely, totally waterlogged (give it a few minutes, maybe an hour or so to thoroughly soak everything) and see how long it takes to dry out. This may still only take a few days in your climate - it will give a benchmark about how much water your plants can take and how quickly it's evaporates.

I suspect that at least some of the time during your summer, your plants will benefit from either of these approaches.

Several of my cacti have been permanently wet for all of July (cold wet month, after warm and very sunny April & May) and are responding by growing and producing buds. As we move into late August onwards, I will be far more careful with controlling the amount of water they receive.

[esp_imaging]

Have you had any issues with leaving them in water overnight? I only ask because I've seen a lot of folks say that will lead to rot, so I had avoided leaving any water in the saucer for any period of time, let alone 24 hours.

No, healthy, easy to grow plants in summer should be fine being soaked for 24 hours.
Context is key. If you have the same plants growing in pure peat on a gloomy windowsill in november at 7dec C/ 45F, then yeah, for sure you are likely to get rot problems, fast. That's a world away from the situation you've described.

[EPPhoneHome]

In a >50% pumice mix, water can just flow through without actually being absorbed by most of the mix. You apply water, it finds a path of low resistance through the mix, and pours out of the bottom without wetting most of the compost.

Ohh, I see now. Thank you so much for taking the time to explain this to me! I will definitely try your experiment, as we're now in a record-breaking heatwave and I need to take good care of these little guys through it! One last question, if you don't mind: I just repotted these guys at the end of June, so they're probably a little more sensitive than usual. Is it still okay to totally soak them, if they're not used to it? Or do I need to wait a little longer for them to adjust to their new soil?

Thanks so much for your input here, I really appreciate it.

[esp_imaging]

Is it still okay to totally soak them, if they're not used to it? Or do I need to wait a little longer for them to adjust to their new soil?

I'd say go for it - roots will heal quickly in your heat.