We are in a severe drought and I am trying to figure out how I am going to prepare the garden for the high temps of summer. We normally have 35 to 45 inches of rain from November through March or April. In a dry year, we get about 25 inches. This year, so far, we have only gotten 1.25 inches. Doesn't look good.

Since I have to go out and glean/collect my own mulch and can't buy any up here, I am wondering what the best materials to use for mulch would be to maintain the moisture in the soil ... which has good drainage ... and how deep I dare mulch without smothering the plants because oxygen can't get through.

I also need to find a way to make inexpensive .... cheap .... plant collars to keep the mulch away from the crowns of the plants.

All help is very welcome.

Smiles,
Lyn

I mulch heavily but fire hazard has never been as issue here. That is the thing that would worry me, if you are in a fire hazard region and so dry.

Lyn, I would contact your County Extension Service people about your mulch questions. They would be knowledgeable about matters that pertain to your particular area and can give you guidance. Just tell them a Mississippi Master Gardener referred you to them. LOL

Ken

@drdawg ..........

That is very good advice, if you have a County Extension Service.

I live in an old gold rush town in the mountains of northern California. Due to extreme budget cuts, we no longer have an Agricultural officer and share one with a neighboring county with a coastal climate which is very, very different than ours.

I don't use the green waste at the dump because too many people treat their "brush" with Round Up to remove ladder fuels for fire safety and then take the stuff to the dump.

I generally mulch with decayed and shredded oak leaves gathered from a friends' property and small wood chips gathered from the utility company's chipping pile.

I've read the rule of thumb is to only put down two inches of mulch because deeper mulching can inhibit oxygen exchange.

I really want to put down a deeper layer of mulch because of our high summer temps ... high 90s to low 100s, to retain as much moisture in the soil as possible from any watering activities, but I don't know if that is wise.

I can glean plenty of pine needles and buy hay, so it's not a matter of not getting mulching materials, but more about how to get through the drought.

I am gardening in glacier debris/subsoil which contains dense rocks with clay and silt. I have excellent drainage. Not too fast and not too slow. (I perk tested every planting area and planting hole.)

I may not have any watering restrictions, but that depends on the water wars between northern California and southern California, but I am planning for the worst.

All advice and suggestions is very welcome.

Smiles,
Lyn

It varies depending on a number of factors. But, in terms of retaining moisture, adding mulch pretty quickly results in diminishing returns. In other words, four inches of mulch is typically only slightly better at preventing moisture loss than two inches, for example. On the other hand, there's a nearly linear relationship between how deep mulch is and how much moisture (from rain or overhead watering) is prevented from reaching the soil surface at all , especially if the water comes in relatively small amounts at any given time. It's easily possible to make your soil drier by adding too much mulch. That's why you commonly see recommendations to limit mulch to a depth of two inches or so. Under "typical" conditions, that's deep enough to limit moisture loss to evaporation, but not so deep that it interferes with infiltration. The challenge is figuring out which variables you have that are not "typical", and what you need to do to adjust for them.

Thank you @KentPfeiffer.

Knowing the "why" of something helps. We get no summer rain, but I am going to have to wash the roses to avoid spider mite infestations and I do want that water to be available to the plants, so I won't mulch deeper than the recommended 2".

I won't be adding any new plants to the garden or transplanting anything as 90% are mature plants and I still plan to water deeply, but I may space it out a bit further by a couple of days. It depends on the summer temps. The plants won't thrive, but they will survive.

Smiles,
Lyn

Coarse mulch will let water and oxygen through easier than fine mulch. It won't hold back as much rainfall or dew as fine mulch would (on the theory that fine mulch can act like a sponge, but coarse mulch acts more like coarse gravel).

I never read that coarse mulch might allow more evaporation than fine mulch, but it seems reasonable that a thin layer of coarse mulch must let humidity escape faster than the same thickness of fine mulch.

>> We normally have 35 to 45 inches of rain from November through March or April. In a dry year, we get about 25 inches. This year, so far, we have only gotten 1.25 inches. Doesn't look good.

Good luck! Maybe 5 years ago I drove through Tulare County, and it was worse than desert. It looked like land that had been irrigated ten years previously, but had not had a drop since then.

Hi Rick ...

The shredded leaves seem to be the best mulch for this garden. Topping them with a thin layer of small wood chips just keeps them from blowing around.

Everything else I have tried may feed the soil, but does not work sufficiently to keep the moisture in the soil.

We have all been asked to cut back our water usage by 20%. My approach is to water more than I usually do during this season and water less during the high temps. My goal is to bring the healthiest plant I can into the summer temps, so that they will need less water to survive.

I am not watering consistently on a schedule because nature doesn't water consistently ... and I think plants are programmed not to depend on consistent water unless that is part of their natural habitat. I haven't made that assumption on any scientific data, but I have seen plants seem to take a harder hit when regular watering in a garden was changed to less regular. The same plants in other gardens where they did not receive such consistent watering seemed to be able to survive better. So, this is just personal observation.

Tulare County has had water sent down from northern California regularly, but it seems like folks down south think there is an endless supply of water and that it is not a finite resource. Thus the water wars.

Rita ... mulching a garden does not create a fire hazard. When you use the "rule of four", two inches of mulch will only create 8" of flame. Generally, that is not a problem. It's the brush and tall grasses on properties further out of town that cause more of a fire risk. A two foot bush can create eight feet of flames which could take the fire up to the trees and any near by structures.

I do live in a wildfire area. Most of the fires are started by lightening. That's one of our biggest worries.

Smiles,
Lyn

>> I have seen plants seem to take a harder hit when regular watering in a garden was changed to less regular.

I could easily believe that, though not from books. Plants that often have to scramble for water probably adapt by putting more energy into growing deeper roots and more root hairs. I have read that root fungi grow thicker on plants that don't have sufficient water or phosphate. They will scavenge what water does appear very efficiently.

Maybe plants that always have plenty of water (until they don't have any) lose some of their leaves' water-conserving ability.

If you have heat, low humidity AND wind, maybe a wind break would let your plants get by with less water. Is there any chance of giving them some shade that might double as a partial wind-break?

Someone mentioned the technique of using irrigation drippers (like dripline or drip tape, but laying it down UNDER the mulch. With your compacted, rocky soil, I bet that any scheme for "deep watering" that requires digging would be "right out".

Rick ...

>>>Plants that often have to scramble for water probably adapt by putting more energy into growing deeper roots and more root hairs. I have read that root fungi grow thicker on plants that don't have sufficient water or phosphate. They will scavenge what water does appear very efficiently.

I think we are on the same page with this one. Even in years when drought was not an issue, I've used this theory to help the roses develop a deeper and wider root mass because of my dense rocky soil. I wanted to encourage the plants to push their roots through the small crevices between the rocks.

When I shovel pruned a rose last year, the roots extended out further than the canopy of the rose. Sometimes the only way you know your theory works is when you dig up a plant ...

The only plants I am going to concentrate on bringing through the drought are the roses and a couple of trees. Everything else is easily replaced. Roses typically abandon any growth they cannot support, so the leaves go first. They will still try to bloom to continue the species, but if the plant cannot support the blooms, it will stop wasting any resources to bloom and go into survival mode, which is a kind of dormancy. I am hoping to induce heat dormancy in the plants so that they will need less water to survive. Yeah ... I am working on theory and have never done this in the past, so I don't know for certain if I can pull it off.

I don't need to worry about wind, but I have been trying to figure out a way to shade the plants because that will slow down the transpiration rate of moisture from the foliage.

I tried using drip irrigation in one bed last year, but the roses showed water stress and I ended up abandoning that method last summer. But I am a beginner in using a drip system and may not have set it up right.

Gardening in dense rocky "soil" is an adventure because water will flow where it can get through the rocks. I could set a dripper underground and it's very possible that the water might end up flowing away from the plant because that's the easier way for the water to flow. Another lesson learned the hard way. Of course, I am always open to suggestions.

Smiles,
Lyn

Lyn, that is good about the mulch not creating a fire hazard. That was something I was not sure about.

Rita ...

A couple of years ago I talked my neighbors into working with me to have a CalFire crew come out and do some fuel reduction work on our properties. I learned about the "rule of four" from one of the crew.

I was surprised to find out that the blackberry patch growing up the seven foot cliff across the road was more of a fire danger to my house than any of the other things I was concerned about.

The owner of that property now keeps those blackberries cut back to nothing every year, so that we don't have to worry about them. They would have created 28' flames.

Smiles,
Lyn

I don't know how drip works when the drainage is good but might be channeled. I think drip rleies on the soil to spread it around horizontally before it passes right down through and out of the root zone.

>> When I shovel pruned a rose last year, the roots extended out further than the canopy of the rose. Sometimes the only way you know your theory works is when you dig up a plant ...

Nice! I agree. "Ground truth" is the Real Thing. We were responding to someone's question about a potted plant and someone suggested looking at the rotos. The answer was almost "Hey! There AREN'T any!" There's your problem!

>> go into survival mode, which is a kind of dormancy. I am hoping to induce heat dormancy in the plants so that they will need less water to survive.

Smart! Working with the plant's nature. I never heard of anticipating dormancy and trying to ease into it, but it sounds like a good plan.

Plants killed by frost aren't always killed by the temperature alone - they're often killed by too RAPID and unheralded a change in temperature. If they had had weeks of 35 F and then 32 F and then 28 F, they might have taken 20 F or 15 F in stride. But not if it goes from 50F to 15 F overnight!

Rick .......

>>>>> go into survival mode, which is a kind of dormancy. I am hoping to induce heat dormancy in the plants so that they will need less water to survive.

>>>Smart! Working with the plant's nature. I never heard of anticipating dormancy and trying to ease into it, but it sounds like a good plan.

I really never heard of it, either. I got the idea from knowing about roses found in abandoned cemeteries, abandoned homestead, ghost towns, etc. Most of those roses never received any supplemental water during the summer months because we don't get summer rains in most of California. The roses were not thriving, but they had survived without any "care".

That's the reason I am watering, now. Generally, the places where those roses were found got sufficient winter rains to keep the plants alive. I am trying to mimic that cycle. Who knows if it will work ? I think it's better to have a plan than to hope we don't have any water restrictions.

Smiles,
Lyn

My roses demonstrated the drought dormancy theory the summer of 2011 when we had no rain from February until November. There are many that are out of reach of any watering and they hunkered down and survived. I do have a fairly thick layer of assorted mulch and previously had soaker hoses under it to irrigate the recent plantings; however the gophers were thirsty too, and the hoses leak all too well now. My roses have learned to be self-sufficient.

The "rule of four" is new to me - interesting!

Thanks for the confirmation, PP.

Smiles,
Lyn

>> Generally, the places where those roses were found got sufficient winter rains to keep the plants alive. I am trying to mimic that cycle.

Great plan, working WITH what the plant evolved for (or at least what it has survived recently!)

I also like your idea of trying out what sounds like it makes sense, and learning from the results. I think that's the only way we all learn new things. Just repeating the conventional wisdom without testing alternatives doesn't discover anything new, and it barely even tests the conventional wisdom.

Lyn, did you ever try to contact your Extension Service County Agent about the mulch question?

@drdawg.......

Yes and no. I did send an email because he has not been over to our County from the coastal county where his office is located. I have not heard back from him.

BUT, you gave me a great idea to contact a couple of the Master Gardeners up here. (Thank you.) Both of them have the same problem really knowing what the best mulch material would be because in our county, this has been a non-issue for all of our gardening lives. They did agree that thicker mulching would not be more beneficial than the normal two inch mulching generally advised. They are going to contact some other Master Gardeners down in the Valley to see if they can get more information and will get back to me.

Smiles,
Lyn

OK, sounds like you have a good plan to get the necessary info. We MG's do serve a purpose occasionally. LOL