Watering of Plants

[templegatejohn]

Cactophiles particularly ones new to the hobby want information about watering their plants. Perhaps this perplexes them more than any other cultivation problem. So let us look at it in a little more detail.

CACTI IN GENERAL:
Cacti as we all know are plants. I says this because many non cacti lovers think differently. One chap once said to me, "are they alive." I bit my tongue and told him yes they were in fact living plants.

Therefore if they are alive they need water. There is nothing alive on the planet that does'nt (unless somebody know different.) Having established that, how much do they need?

CACTI IN OPEN GROUND (In the Wild, or the Garden)
Cacti generally and globular cacti in particular usually have a very weak root system. In open ground the roots tend to spread out very close to the surface of the soil. This then gives them the ability to "gather in" any moisture that hits the surface of the soil. Most cacti have ribs in one form or another These ribs allow the body of the plant to swell and contract “like a concertina.” This action allows the plant the opportunity to take on board quite a large quantity of moisture at one go. The spines also trap water and direct it down the plant to the roots. The poor old cactus does not know when it will get another chance so takes on board what it can get.

CACTI IN POTS:
These plant are reliant upon their owner to provide them with the care they need. Surprisingly there are almost as many cacti growers underwater their plants as over water them. Both will kill their plants. The overwatering brigade just do it more quickly.

We have already established that cacti need water. The trick is knowing when to water and when to withhold water. If we say that between mid-October and mid-March we do not water we are on the right track. If the plants are kept at 50f. or higher, a small amount once a month should be adequate.

One we start to water in mid-March a little is sufficient and not until you see signs of growth on the plant. Once we are into late April, early May normal watering should be resumed.

WHAT IS NORMAL WATERING?:
Water the cacti as you would any normal house plant, but allow it to drain (do not let it sit in a saucer of water). DO NOT WATER AGAIN until the soil is almost dry and then give it another good watering. Some people say do not water the plant from the top, but unless the plant has a waxy bloom or dense wool this in my opinion is not necessary.

The main root system of the plant is there mainly to anchor the plant into the compost. The roots that take up the water are the "hair roots" and these are easily killed if they are in constantly wet compost. Hence the advice to let the plant dry out before watering again. The hair roots can be re-generated by the plant roots, but older roots loose the ability to do this. Therefore at re-potting time it is a good idea to trim the roots by up to a third, this encourages new young roots to grow and send out hair roots looking for moisture.

HOW DO YOU TELL WHEN THE POT IS DRY:

Well it is not always easy particularly if you dress the top with gravel, but there are one or two ways. If the pot is a clay one (terracotta), it will probably dry out more rapidly than a plastic one, as it drys out it will probably also go lighter in colour. This change in colour can sometimes be noted travelling down the side of the pot. If the pot is on a glazed saucer or something similar, while the soil is still moist there will usually be signs of this when you lift the pot off the saucer (small globules of water) or at least some sign of dampness. When the dampness is no longer there, give it another couple of days (depending on the weather) and water again.

If the pot is plastic it becomes a little more difficult. Get used to feeling the weight of the pot just after you have watered. As the moisture leaves the soil the pot will become lighter in weight and with a little experience of doing this you can gauge when the plant requires more water.

I think that is enough for now. Although I have attempted to give some detail, in many ways it is still a generalisation. For example: Some cacti have tap roots or tuberous roots, these can also store water for the plant. Plants that are in full growth and flowering will take up more water etc. Don't forget that some cacti in the hottest part of the summer go into a mini rest period. Don't water if there is no sign of growth on the plant.

I hope the above is of some interest and help. It should be used as a guide and not a hard and fast rule.

John

[tillie]

For me, watering true cacti seems to work best when done from the bottom, but it doesn't seem to matter with succulents. I water them from the bottom too though, mostly out of habit. Cacti, when watered from the bottom, seems to be hardier to me. I'm guessing it's because it encourages the roots to spread out. I've never had a cacti that I watered from the bottom develop rot, and actually the only thing that's developed rot since I started watering from the bottom was an aloe just recently. I've been watering this way for nearly three years.

With my bigger cacti, I can tell when the soil is dry by giving a poke into a drainage hole. I usually water all my plants at the same time though, and when my jades start getting wrinkled I know it's time to water. I have some kind of fishook barrel cactus and when it needs water, it's spines pull closer to it's body. You have to learn to look for the subtle signs, I guess.

[cactusbutt]

Great read John
should my cacti get more water when flowering?
Or should i keep with my regular watering?

have a good one

Bob

[templegatejohn]

Hi Bob,

Great internet bar here.

In answer to your question I personally would not increase the watering, but it is always a good idea when you see the flower buds forming to give the plant a boost with a dilute liquid feed. It takes a tremendous effort by the plant to produce flowers and this will always help.

Cheers,

John

[monrad]

Tillie,

When you water from the bottom, do you just pour water into a saucer the pot sits on or do you place the pots in a container of water?

Kind of courious. I set my small 2 inch pots in a container of water so I don't disturbe the small seedlings watering from the top. That works well, but I have read that watering from the top down can help wash away built up fertilizer and help wash in oxygen. Maybe a mix of watering alternating from the top and then the bottom would be a good compromise? I don't know. Just the ramblings of an over-read detail type guy. What do you think?

[tillie]

If I use a saucer, I usually place a few small pots in it and let them soak it all up. Right now I have a few tupperwares set out to catch rain though, and I let them sit until the pot is dark about halfway up.

If it's not raining hard, I'll let my cacti sit out. So I guess they do get some watering from the top.

Actually, I don't think cacti are as picky about water as I think they are.

[templegatejohn]

Hi all,

Yes it is true that watering from the top helps to drain away the build up of salts etc. that accumulate when using fertilisers.

In my own opinion it is better to water from the top and allow the pots to drain (but not into a saucer underneath). Not everyone will agree and it is horses for courses. If it works for you why change?

There is however one problem when allowing plants to soak up water from a saucer or other container and this is particularly true of many globular cacti. If water is available to them they will continue to soak it up until the epidermis (body) of the plant splits.

Many people use the "soak up" method after the plants have been dry through the winter, particularly if they use a peat based compost which is notoriously difficult to re-wet. A much better way at this time is to add a little "washing-up liquid" to the water to act as a wetting agent.

Perhaps when watering very young seedlings watering from the bottom is a better proposition if it is done with care and the plants are not left to stand in the water for more than 15 minutes.

Cheers
John

[Conan]

wow, very interesting. I'm quite new to the hobby in terms of knowledge, and for many years I learned by a "what works and what doesn't" method. I never thought to go online.

Anyways, the watering around the year advice is great as I was wondering exactly that, but I was also wondering if you need to repot every year. I did not find a thread about that, but I only looked on the first page. Is there somewhere where this repoting is discussed in such length as the watering procedure?

Another thing is when do cacti flower? Do you need to fertilize to make it happen? Mine never flower, perhaps because this summer is the only summer that the plants are really doing well.

Thanks for the info

[templegatejohn]

Hi Conan,

As regards repotting, as a general rule young plants should be repotted every year. Older plants can be left in pots for many years and fed rather than repotted.

A general rule with globular plants is to have about an inch of room all round the pot, columnar plants will almost tell you when to repot (they start to fall over).

You can feed cacti, but it is normally done at half the recommended strength on the bottle and perhaps once every six week.

As regards flowering, for our purposes, yes all cacti will flower but they have to reach maturity to do so. Some may do this in a couple of years, others will take many many years before they get to the flowering stage. Without seeing photographs of your plants it is impossible to say why they are not flowering.

All that I can recommend is that if you have had the plants for some time and they have not been repotted then I would do so. If you can do it now that would be OK, otherwise wait until the end of March next year and then do it. At the risk of repeating myself make sure the new compost is "open" i.e. one third grit or perlite to two thirds compost, is a good general mix.

Hope this helps.

Cheers,
John

[Conan]

Thanks for the info, though this raises more questions, mainly:

A general rule with globular plants is to have about an inch of room all round the pot, columnar plants will almost tell you when to repot (they start to fall over).

I assume globular refers to globe or rounds cacti and columnar to a column or straight-standing cacti? Are there other kinds?

You can feed cacti, but it is normally done at half the recommended strength on the bottle and perhaps once every six week.

Here you mean fertilize and during the winter, right?

Without seeing photographs of your plants it is impossible to say why they are not flowering.

I'll try to take a pic tonight or tommorrow.

one third grit or perlite to two thirds compost, is a good general mix.

I use a pre-mixed bag or cacti soil that I buy at Walmart or so. Is that sufficient? When you say "compost" do you mean compost from my compost bin in my back yard made from food scraps that I blend in my garden? Or do you just mean normal potting soil?

Hope this helps.

Yes it very much did. Any good books you'd recommend for indoor cactus growers such as myself?

Thanks

[templegatejohn]

Hi Conan,

Yes there are other kinds primarily climbers or trailers.

No do not fertilise in winter, only summer in the growing season. I should have made that clear.

When I talk about compost I mean the soil in the pots.

The compost you are buying is adequate, but most cacti enthusiasts like to mix their own. If it is free draining it is OK.

Regarding books, look on the web at Rainbow Gardens Bookshop, which probably has the largest selection, or type in Cacti and Succulents on Amazon.com, they have pages of them. I have lots of books but many of them are now out of print so it would be pointless recommending those. "The Cactus Family" is the current cactus "bible" but may be a little advanced and also expensive for someone just starting out. There are lots of good ones out there it is just down to your personal choice. "The Ultimate Book of Cacti and Succulents" by Miles Anderson is a good general book with lots of useful information and superb pictures. I would suggest that is the type of book that would cover most things an enthusiast needs to know, watering, different "soils", seed sowing, problem pages etc.

Cheers,
John

[JuanKilo]

I use water that has sit overnight in a couple of five gallon buckets, that way the chemicals from my local city water treatment plant dissipate overnight greatly.

I top water most things, execpt some copiapoa that have a coating that can wash off. I fertilize every watering at half strenght on the fertilizer recipe. I'm in Nebraska, so it gets hot here, and lately I've been watering every other day for larger pots, and daily for smaller pots, say 3" and under. My plants are outside, and do recieve rain water.

I have some larger cacti in very shallow terra cotta pots that are 7" wider or more, yet only 2-3" deep, and these I bottom water. Just doesn't seem to absorb the needed water otherwise from a top watering.

I also use a top dressing over the soil for my cacti. It does provide a bit of shade for the soil, which keeps the roots cooler a bit, keeps the plant clean during watering, and looks a bit better than just soil. Aquarium gravels work well, with many colors to choose from to compliment the cactus. Well washed river gravel works, crushed aggregates of your choice will do. Reasons for using this are listed above, and also help to keep the base of the plant dry, or allow it to dry faster after a watering, which reduces the risk of diasese setting in. I plant cactus a bit high after learning the hard way about a wet cactus body, caused some scaring on one, caused some insects to invade another treasured plant. So, planted high, I raise the level with the gravel so the plant appears at the right depth.

[Mike]

[quote="templegatejohn"]Don't water if there is no sign of growth on the plant.

Hi John,

Re the above, it has been over 35C here the last month and I have been watering weekly. I am not sure I have seen growth on a lot of them, and not even sure I can tell on the globular ones like gymnocalyciums (althougth they flower). Given the heat, it seems root rot is impossible now - what is the risk by watering during summer dormancy? Perhaps the only problem i have had is the Echinocereus pink lace, where an offshoot split - I don't know if it was too much water, or that it fell, or a combination.

Re LA, a number of the cacti say no water in winter (the ones I have seem to be uebelmannia , E. rigidisimus and lady fingers; P. Leninghausii and scopa. Astrophytums. C. senilis and oreocereus (almost no water – root rot issues). E Huascha needs none. I think Daiv had said in LA some water is still advisable. What do warm weather folks do for these kind of "no water" plants in winter.

Thanks much, Mike

[templegatejohn]

Hi Mike,

People are under the impression that the hotter it gets the more cacti like it. To a degree this is true, but plants in their natural habitat usually get a cool night after the hot day and this is the ideal for them.

If it is very hot most cacti will go into 'summer dormancy' (a fact you picked up on), while they are in this dormant period the roots will not take up moisture. The plant will live off its stored supply and there will be very little, if any sign of growth. I personally would not water until you are sure that the plant has come out of its dormant stage.

Regarding watering in winter, I cannot pontificate about watering in a place I have never even visited. I am sure Daiv knows his growing conditions very well. The only point I would make is that plants have an in-built clock and they know when it is supposed to be winter (whatever the temperature is) for example in succulents some plants from the southern hemisphere put on all their growth in our winter because their 'body clock' tells them that is really summer where they originate from, if you get my drift.

Regarding the Uebelmannia I would be very careful about your watering regime at any time of year with this species, they keel over if you look at them and in winter a small and I mean small amount, about once a month is more than adequate and it will need to be kept much warmer than your other plants through the winter, perhaps 10 deg. f. higher.

Your own personal growing conditions and experiences will dictate how your plants fare through the winter. Watch them carefully, sometimes they almost talk to you.

John

[daiv]

Well I'm on the coast so my conditions are more fair than inland. All of my cacti are outside so they get watered with the rest of Southern California in the winter. This has never bothered any of them until this year. With the incredible amount of extra water we got this last season, I ended up with some damage on my cacti. The cells actually burst and leave an ugly brown scar. This was only on a couple plants, however and most of the rest had no trouble. I find that if the soil drains well enough, then you can and should water more frequently. Plants in pots need more water than those in the ground. I water my potted plants once a week. In my case, I found watering lightly more often created better results than a lot of water less frequently. Instead of changing the times I water, I just use less water when it is cooler and more when it is hotter.

As for the climate in So. Cal., I think you could pick any two days in the year and get the same exact temperatures for each day. Although the average temp is about 20 degrees lower in winter in my area I would say.

Plants in the ground are a lot more tricky as you can't individually adjust the conditions for each plant. I find that smaller plants need water more frequently than the larger ones. I water them all about every other week in the summer and every 4 weeks or so in the winter. I must say that I've only lost one large plant from rot, but I suspect other problems with that one. I have lost quite a few smaller plants that didn't get enough water.

I think it is important to note that many (not all) cacti are "oportunistic" growers and do not require a season. If conditions are right, they just keep growing. You can see this in action by visiting a big cactus nursery like C&J in Vista, CA. They have lots of greenhouses with Cacti growing very happily all year round.

Daiv