Even in the best managed gardens, as soon as the soil warms up weed erupt and need to be controlled before they get the upper hand. Different soils and conditions produce differing unwanted species and it pays to be able to identify them in order to know what is growing in your garden and how to manage them.
It is best to deal with weeds as they germinate and before their roots get a hold, and certainly before they flower and seed or there will be an even worse problem the following year. The most efficient and least labor intensive way is to use a hoe.
I keep a hoe in readiness close to the vegetable plot and use it almost daily during the growing season as soon as I spot an invader. My personal favorite is the Hula hoe which is stirrup shaped with a blade sharpened on both sides so it can be used to cut through young weeds just below soil level on both the push and pull strokes. It is very efficient on cultivated soil so long as the plants are small. It will not work to remove weeds from turf, neither will it cope with thick clumps of established Bermuda grass or any woody plant that has a thickened base. It is not wise to hoe plants that increase by rhizomes such as nut sedge or bindweed since the hoe is liable to chop the roots into pieces that readily form new plants making the problem worse. Those plants are best dug out individually, getting as much of the root removed as possible.
A hoe will not remove a dandelion root in entirety but at least regular removal of leaves will prevent flowering and seeding until such time as it can be dug out.
For areas where the Hula hoe cannot reach, my favorite tool is a Japanese hand hoe which has a sharp triangular blade and very useful sharp corners. Plants with long tap roots such as dandelion and salsify can be removed with a forked device, the prongs of which are placed at the neck of the plant, while an angle in the handle increases leverage. However, for weeds growing very close to plant stems or in places where there are surface roots that may be damaged by hoeing one just has to get down on ones knees and hand weed.
Reduce the possible spread of seeds by immediately discarding any weeds that may have already set seeds. Spotted spurge is able to produce seeds on quite tiny plants and a mature specimen can shed thousands of them so it is important to put any removed plants directly into a container or bag, and don't be tempted to shake the soil from the roots since this will result in seeds being scattered far and wide! Don't leave piles of weeds in heaps waiting to be collected later, since dandelion seeds will quite cheerfully manage to blow off into other areas. The bottoms of lawnmowers can deposit grass seeds onto surfaces as they are moved from place to place and these can then be blown back onto the garden.
If you are not sure of the identification of a particular weed in your garden the following link should help you. Once you have identified the culprit select the page for a description of that particular plant and then go to the bottom of that page and select “Pest Management Guidelines” http://ipm.ucanr.edu/PMG/weeds_intro.html
These are some common weeds in our area and links on how to identify and manage them:
Spotted spurge: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7445.html
Field bindweed: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7462.html
Russian Thistle (Tumbleweed): http://ipm.ucanr.edu/PMG/PESTNOTES/pn7486.html
- Author: Dustin Blakey
I always like to grow some flowers in my garden. I usually grow cosmos, zinnias, or marigolds, all of which do great in the Owens Valley.
This year I had a great plan to try to have my garden mostly done by July. It didn't work out, but before I abandoned that goal, I planted bachelor's buttons. These annual plants flower quickly, and I had hoped they would be ready in time for graduation day in June. And they were. Sort of.
Bachelor's buttons—also called cornflowers—are in the same genus (Centuarea) as many thistles that do great in California. Some in fact are terrible weeds like yellow star-thistle: C. solstitialis.
I've never grown them here myself, but bachelor's buttons are about the world's easiest thing to grow. Just maybe not in the desert when it's blazing hot. (In my defense, I suspected they wouldn't like our summer. I was trying to finish up the garden before the heat was unbearable in my back yard.)
Some Centaureas do like our climate. Centuarea montana, a similar looking perennial plant, looks nice in the Owens Valley. Centuarea cyanus, at least when direct sown in the garden, was a disappointment for me.
Here is what the flowers look like in the seed catalog:
In my past experience growing them, that's a fairly accurate representation of what to expect.
Here is what I ended up with:
As you can see in the picture, the flowers don't look so good. What's happening? Well, my garden is too hot. As soon as the blossoms open, they immediately desiccate. I suppose if I wanted to dry them that would be fine.
Bachelor's buttons like cool weather, and I planted these in early March. I had no issues with germination. They quickly popped up just like the weeds they're related to. Everything worked as planned, and my first blooms began Memorial Day weekend. (Hooray for planning ahead!) But then they just fried on the stems.
It could just be this particular mix. I'm sure it did fine in Oregon where the seeds came from. In my garden every day, even with ample water, these plants get a bit wilted in the afternoon. Other cultivars may do better, but I don't think I'll experiment again to find out which those may be. (If you have good luck with one, post in comments.)
From this experience, I'd recommend one of these strategies if you want to grow bachelor's buttons:
- Plant the perennial relative C. montana
- Start the seeds indoors in February and transplant to finish sooner
- Pick a cooler part of the yard and not in a hot corner like I have, or use a light shade cloth to lower the temperature
Higher elevation gardeners would probably be much happier with bachelor's buttons than I was. For my part, rather than moving up the grade and trying again, I think I'll stick with zinnias next year.
- 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.
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.
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.