- Author: Carmen Kappos
“Overwatering is the number one killer of houseplants,” says Mr. Ernesto Sandoval, Manager and Curator of the UC Davis Botanical Conservatory. Overwatering encourages disease, pests, and can smother roots that need oxygen. With overwatering, roots can die and rot.
When to water depends on many things: the type of plant, the amount of light, temperature, the potting mix. All these things have an effect on when the plant will need water. So how to tell when to water?
Here are some good tips on determining when to water your houseplants.
- Your finger is a really good moisture meter. Use your finger to check for moisture in the top 1” of potting mix.
- Leafy plants: let the potting mix start to dry until barely moist between watering.
- Succulents and stem succulents: the top 1” of potting mix should feel mostly dry between watering.
- Get familiar with how heavy the pot is right after watering, dry potting mix is much lighter in weight than when it is wet.
- Dry potting mix is also lighter in color than wet potting mix.
- Water so that some water drains out the hole in the bottom. This ensures that the water has gone into the entire pot and has reached the root zone.
- Do not let the pot sit in water, empty the saucer or tray after watering. Drained water contains salts and minerals that can be reabsorbed into the pot. This briny water is not good for the roots.
- Pots can be elevated with material like pebbles, in the tray, to keep the pot from touching drained water.
- Usually tap water is ok to use for most houseplants, however softened water contains salt that will quickly kill plants. Water with Boron should not be used on container plants.
- Water from wells may be ok to use, it depends on the amount of minerals dissolved in the well water.
- If there is a buildup of crusty minerals on the pot or potting mix, gently remove the crust and flush out the pot with clean water that does not have minerals, then let drain.
- Use a well-draining potting mix. Most commercial potting mixes hold too much water. Small pumice rock sold at plant nurseries can be added at half the total volume to improve drainage in potting mixes.
The UC Davis Conservatory houses over 3000 plants in more than 150 different plant families. Responsible for the care and development of the collection, with a degree in plant biology, Mr. Sandoval has watered and cares for many plants. In his video talk on houseplants Mr. Sandoval advises to err on the side of under watering. Check out his talk on houseplants at: https://youtu.be/n60Iia0XxUE
Bonus tips from the editor: If you're seeing lots of little gnats buzzing around the pot, you're probably keeping the plants too wet. Seeing lots of burned edges on leaves? Either you have accumulated salts or may be getting plants too dry between waterings.
- Author: Alison Collin
At this time of year it pays to check any cherry trees for infestations of black aphids, Myzus cerasi. These appear most usually on the tips of the terminal shoots, but also on the spurs and they tend to prefer sweet cherry varieties over the sour ones. Leaves will crinkle and curl over, and become sticky with aphid secretions which in turn encourage the development of sooty mold that in severe cases may render the fruit inedible.
These aphids are shiny black and about 1/8-inch long. They overwinter as eggs on the tree bark and emerge at bud break when they feed on tender shoots, injecting a toxin into the leaves which causes them to curl thus protecting the aphids' increasing numbers.
UC IPM recommends using dormant oil sprays in late winter, and hosing off with jets of water any aphids that are obvious before the leaves curl. As with all aphid infestations keep an eye open for ants traveling up the tree trunk – a sure sign that they have found a good supply of honeydew. Natural predators such as hover flies, lady beetles, and lacewings should be encouraged, but once the leaves curl over, these insects appear not to be so prevalent. At that point water jets really are not effective, either.
On a young tree I have used a bucket of soapy water and bent the stems into it so that the affected regions are well submerged, but this is not possible on a large tree. Sometimes leaves are so infested that ones best option is to simply prune off the infected twigs, placing them directly into a plastic bag, and disposing of it.
Other cultural measures which may help are avoiding lush growth in the spring by not over-watering or using high nitrogen fertilizers. The base of the tree should be kept clear of weeds or other plants that may act as summer hosts.
- Author: Alison Collin
In the last few years there has been an interest in “no till” methods of gardening that propose numerous benefits such as increased yields, less physical work, and much healthier soil cited as reasons we should stop digging our soils. However I wonder if this method of growing is really suited to the environs of desert areas? Here are some thoughts of mine on the issue.
Let's start with what “no till” growing is, and how does one go about doing it.
There is more than one way to accomplish a "no-till" garden but the most commonly advocated method is sheet mulching. (It goes by many names.) As the name suggests, the soil is not dug in preparation for growing food or ornamental plants but rather the top of the soil is regularly amended with organic matter which works its way down into the soil to feed the roots of the plants from above. To start a new growing bed using this method, a layer of cardboard is put over the surface of the ground in order to suppress existing weeds. Then a deep layer of well-rotted compost is laid over the top and crops are grown in this. Plants are mulched to retain moisture, and over time the cardboard rots and worms take the compost down into the native soil. This is considered to be closer to how plants and soils interact in the natural world.
By contrast, hand digging or rototilling disturbs the natural profile of the soil by destroying earthworm burrows and bringing the natural and beneficial mycorrhizae to the surface where ultraviolet light and drying conditions kill these fungi. It also interferes with the natural drainage of soil so dug soils drain poorly compared to the compost in no till beds and soil loss by wind erosion is increased.
There is a lot to be said in favor of the no till method. However, is a no-till method like sheet mulching suitable for desert situations with a very low natural rainfall? Most of those who advocate this method of growing and have the greatest success live in high rainfall areas where precipitation is regular throughout the year, and often the rainfall each month is as much as our desert area receives in a year! We also have very dry air with a relative humidity often less than 10%, with frequent, quite strong, drying winds. Our natural vegetation is sparse and prickly as a result of the climate, and things decompose very slowly.
Beneficial to the soil as “no till” might be, some arguments in favor do not hold up in our area. Supposedly it is less labor intensive since one does not dig, but to produce the amounts of compost needed in our area for this method to work, one either has to constantly turn compost heaps, or else buy compost in bulk (assuming that you can find a local source), pay for it to be delivered and then barrow it to the growing area! Our environment makes it hard to even acquire something to make compost from in sufficient amounts.
Then there is the tremendous water usage, both for keeping one's compost heap working and then keeping the applied compost damp enough for these benefits to occur in the garden. Everything dries quickly in our wind, sun, and heat.
Mulch such as wood chips takes a long time to rot down in the desert but without some protection our desert winds can certainly remove loose topsoil. In my experience they are equally efficient at removing the finer particles of mulch, leaving only the sticks behind. Often I have put a deep layer of shredded leaves around plants and on top of the drip irrigation tubing but this fine mulch, far from rotting down or being taken into the soil by accommodating earthworms has rapidly vanished into the next county during our high wind events. This does not happen so much if the mulch surface is kept wet, but can we afford to use that much water when facing a serious drought?
When digging I always incorporate generous amounts of compost or manure or any remaining surface mulch into the ground where it will not get blown away and will be in close proximity to the roots of my crops. I dig in winter when earthworms are very deep in the soil but by spring I have an extremely healthy population.
In many places in the desert where the soils are sandy and alkaline, earthworms are a rarity - if present at all, so in these cases the downward movement of organic matter placed on the surface is not likely to happen for several seasons, and indeed where I have raked several year's accumulation of leaves from under shrubs, even the bottom layer hardly shows any evidence of the leaves breaking down.
No till's proponents admit that slugs and snails are common problems in the compost-grown vegetables, although I doubt whether that would be much of a problem here, but I did mulch heavily with straw one year and consequently had the worst European earwig infestation that I have ever experienced.
Our desert soils certainly need a lot of help in the form of organic matter if they are to produce crops, but it is difficult to know which is the best way to achieve that. As with most horticultural endeavors there are pros and cons to both methods but it pays to think of different options, and perhaps do a trial bed before embarking either method on a large scale.
Editor's note: Another consideration is the population of weeds present. At least in the Owens Valley, our perennial weeds, especially Bermudagrass, emerge through the cardboard layer quickly since it is insufficient to stop them. A gardener would have to eliminate perennial weeds first. Our wind also brings in fresh seeds of wind-dispersed annual weeds that grow well in the rich, organic layer.
- Author: Dustin Blakey
I was out last night above the river to take some pictures, and I noticed that as the sun went behind the mountains I was joined by some unwelcome visitors: mosquitoes.
I suspect they were males as I didn't end up with any bites, and they were mostly hovering above me. A few landed so I squished them. I don't know what kind they were other than "generic mosquito." I was in the same area last week and didn't encounter any, so I think it's just starting.
All this to say, it's probably worth thinking about taking typical mosquito precautions when recreating outdoors in the evening away from town. Here is some information about mosquitoes from UC IPM.
The Owens Valley Mosquito Abatement Program has a good page on Facebook that updates progress. You can like their page to keep informed. https://www.facebook.com/OVMAP/
- Author: Dustin Blakey
There is a lot of variety in the job of a farm advisor. Some days I'm working with water quality. Other times I answering tree questions. Today I had an insect to identify.
It took a little work, but the insects were banded ash borers.
- obvious yellow stripes
- a slender form
- long antennae
- sturdy legs