Hero Image

What's Hot Archive 2020

What's Hot in January

mole surface burrow
by Barbara Hill

I have noticed a lot of underground rodent activity in my yard.  How can I tell if I have gophers or moles?

Actually, gophers are rodents, and moles are mammals. Moles eat worms and insects while gophers eat roots and other plant parts. The easiest way to tell if you have moles or gophers is to look for surface burrows or tunnels created by the moles. These shallow tunnels create a distinct raised ridge in the soil. Gophers tend to dig deeper and do not create raised ridges.  Although moles usually do not eat plants, they tend to dislodge plant roots which dries them out. Gophers, of course, will eat your plants!  Another way to tell the difference is to examine the dirt mounds. Mole mounds are circular and gopher mounds are more crescent shaped. Gophers are especially active creating mounds during this time of year when the soil is moist and easy to dig. See UC IPM Pest Notes on Pocket Gophers and Moles for more information.

What's Hot in February

by Barbara Hill

Last summer, a lot of the leaves on my plum tree curled up. What could be causing this?

Your plum tree was likely suffering from an infestation of leaf curl plum aphids. These insects appear in the spring, and gravitate to the ends of branches, were they suck plant juices from new, tender growth. This causes the leaves to curl tightly, providing aphid colonies with a convenient hiding place in which to safely feed and breed. Heavy infestations can negatively impact tree growth, as well as fruit size and quality. Sooty mold fungus may also appear, affecting the tree’s ability to photosynthesize. While there are a number of beneficial insects that prey on these pests, chronic infestations often require treatment.

These aphids lay their eggs in the fall, near the base of plum tree buds. Two treatments of horticultural oil applied as buds are swelling may be an effective control. As trees begin to leaf out but before infested leaves curl, strong jets of water can be used to knock the aphids to the ground. Provide pollen- and nectar-providing plants to attract and support aphids’ natural enemies, and avoid pesticide use that may harm them. Closely monitor your tree next spring while it’s still dormant, and retreat as necessary.

For more information visit the Real Dirt’s article on Plum Leaf Curl
Photo by Lennart Tange 

What's Hot in March

by Barbara Hill

What is straw bale gardening?

Bales of straw—that is, the bundled, post-harvest stalks of a seed crop, such as rice, wheat, or barley—can be turned into productive gardens with ease. Essentially a form of container gardening, just a few bales can turn any sunny corner of the yard into a crop-producing paradise. A low-tech (and -cost) cousin of hydroponics, this technique is an excellent option for locations cursed with contaminated, diseased, or otherwise inhospitable soils. An added bonus for the gardener: since the bales are around two feet tall, minimal stooping is required!

Pre-conditioning the straw is necessary, a process that takes about two weeks. Seedlings may then be planted directly into the bale or, with the addition of a bit of potting soil, plants may be grown from seed. With regular applications of water and fertilizer, nearly any crop you'd grow in the ground will thrive in straw bales.

At the end of one or two growing seasons, the straw can be used as soil amendment or mulch, or as an excellent addition to the compost pile.

Straw Bale Gardening (pdf)
Gardening with Straw Bales (pdf)

Photo by Tom Britt.

What's Hot in April

tomatos and basil
by Barbara Hill

When should I transplant my tomato and basil seedlings?

You must be dreaming of bruschetta and caprese salads! Certainly, nothing says “Summer” like the taste of home-grown tomatoes and just-picked basil. Sadly, although the shelves of many big chain stores have been overflowing with these warm-season favorites since February, it’s possible your soil is still too cold to tuck such heat-loving veggies and herbs into the ground.

This may seem counter-intuitive, given our recent spate of unseasonably warm days. But soil gives up winter’s chill very slowly, and tomatoes, along with eggplants, peppers, squash, cucumbers, beans, and pumpkins, hate having cold toes. They will stubbornly refuse to grow until soil temps are at least sixty degrees, which in our region, might be the very end of April, or even later. Without active growth, these plants are less able to fight off bad guys, and may succumb to insect predation and disease. Basil, as a native of tropical regions, is equally fussy about soil temps, and even more temperamental about ambient temperature. All warm-season plants should be set out after all danger of frost has passed, so check the forecast before planting, to avoid an unexpected cold snap.

To give those yummy veggies the best possible start, consider the modest investment of a soil thermometer, and start testing mid-April—or even earlier, if you’re using raised beds.

Learn about:

Photographer: monicore 

What's Hot in May

by Barbara Hill

What are those greenish-brown tassle-like growths that have been falling from my oak trees?

The growths that litter the ground under oaks every spring are called catkins. The term comes from the now-obsolete Dutch word katteken, meaning "kitten", owing to their resemblance to kitten’s tails. Although they’d never win a ribbon at a county fair, catkins are, in fact, flowers— in this case, male flowers. Look closely, and you’ll see that each stem in a cluster is lined with dozens of tiny inflorescences. And if those male florets strike you as insignificant, wait until you see the female flowers...or not. They’re so small, a magnifying glass is often required for a positive ID.

Of the four primary sexual systems of trees (monoecious, dioecious, cosexual, and polygamous), oaks are monoecious: each tree produces both male and female flowers. A few weeks after the catkins first appear, the male flowers begin to release thousands of pollen grains. No pollinators are required: wind plays the part of Cupid, wafting the grains to nearby female flowers. Lest that sound a tad incestuous, worry not—to maintain biodiversity, oaks are self-incompatible: only a very small percentage of self-pollination results in viable acorns. Within a week or so, the catkins will have released all their pollen and, mission accomplished, begin to turn brown and fall from the trees.

For More information: Are your trees boys or girls?

Photographer: Eugene Zelenko 

What's Hot in June

fruit trees
by Barbara Hill

How much water do I need to give my fruit trees this summer?

Making sure your trees are given enough water to prevent drought stress is important in maintaining tree health and fruit quality. But just how much is enough? That’s where things get a bit complicated.
When we breathe, we release water vapor. Similarly, plants release water from specialized cells in their leaves, a process called transpiration. Ever notice condensation inside a bag of fresh lettuce? That’s caused by the leaves transpiring. Combined with evaporation—water lost to the atmosphere from the surface of the ground—we get “evapotranspiration,” aka “ET,” which is expressed in inches per day.

That’s the magic number for growers since, generally speaking, the amount of water lost to ET is the amount that must be replaced by rainfall or irrigation. Determining a precise amount takes into account many factors, with solar radiation, ambient temperature, and the size and age of the tree being paramount. Irrigation techniques, soil depth and type, elevation, relative humidity, and air movement also play a role.

Trying to wade through all these factors is enough to make an apple lover cry. Fortunately, UC Davis experts have done the heavy lifting for us, by providing this easy-to-follow watering table. For a deeper dive, check out The California Backyard Orchard’s guide on irrigation.

What's Hot in July

sun through the trees
by Barbara Hill

Is it okay to plant new perennials in the summertime?

Most every gardener has succumbed to the lure of a gorgeous new plant in the dog days of summer.

While experts agree the best time of year to add perennials to your garden is in the fall, there are a number of things you can do to help a new specimen weather the Central Valley’s harsh, dry summers. Providing ample water is the first priority, both before and after planting.

Start by fully submerging the pot, and while the rootball is enjoying a good soak, give the entire plant a light shearing, trimming back its stems by about one-third. Plant early in the morning or later in the evening to reduce transplant shock, and add organic fertilizer to the soil per package directions: its mycorrhizae will give emerging new roots a healthy boost. Once your plant is nestled in, encircle it with mounded soil, a hand’s breadth or so from the crown, to keep the wet stuff in the root zone. Water thoroughly and cover the soil with a thick layer of finely-textured mulch. Provide shade to protect from hot sun, and water deeply two to three times per week for the rest of the season; more often in windy weather.

Even the tenderest of care won’t always be enough to mitigate severe weather, but if you’re able to shrug off a loss or two, go ahead and take the planting plunge this summer.

Visit the Summer Plant Guide by UC Davis Arboretum for more information.

What's Hot in August

sun scald on a tomato
by Barbara Hill

What’s causing my tomatoes to get white, leathery patches that turn black and rotten?

Your tomatoes are likely suffering from sunscald. Tissue damage can occur in fruits and vegetables that are suddenly exposed to hot, bright sunlight. It’s especially common in tomatoes, peppers, apples, grapes, and raspberries. The tissues may become discolored, blistered, or desiccated, leaving bleached and sunken patches on the affected area. The damage provides easy entry for bacteria, fungi, and hungry insects. As you’ve discovered, it’s a favorite growing medium for black mold, which eventually causes the fruit to rot.

Sunscald can occur due to sparse foliage or the seasonal shifting of the sun. Encourage your plants to step up their shade game: regular watering and a dose of slow-release fertilizer at planting and full blossom will produce plenty of healthy foliage. Use shade cloth or similarly lightweight material to protect exposed fruit from intense sunlight. And keep a sharp lookout for leaf-chomping pests, especially the dreaded tomato hornworm, which can devour up to four times its weight in leaves and fruit each day.

More information about:

Photographer: Howard F. Schwartz 

What's Hot in September

by Barbara Hill

What is kohlrabi?

This previously underrated, unusual-looking vegetable is starting to get some traction in our gardens and our kitchens—and no wonder: it’s a versatile, nutritious, quick-growing Brassica, which easily graces both fall and spring beds.

Rather than developing a head like its cauliflower cousin, kohlrabi—“cabbage turnip” in German—produces a bulbous stem just above the soil line, which is studded with wild, waving leaf stalks. While this little Sputnik lookalike may garner stares, its crisp texture and sweet/savory flavor is sure to please palates. As for its culinary uses, the sky’s the limit: add raw stems to salads, slaws, or veggie dip platters, or turn up the heat and try them steamed, stuffed, roasted, pureed, or even grilled. And don’t toss the greens—or rather, do: they make tasty additions to stir-fries and salads. Learn about kohlrabi.

Photographer: Holger Langmaier

What's Hot in October

garlic braid
by Barbara Hill

What’s the difference between softneck, hardneck, and elephant garlic, and how do I grow them?

A nutritious member of the onion family, garlic is an excellent addition to cool season gardens. Although it can be sown in the spring, autumn planting will result in a crop of superior size and quality. You’ll reap delicious rewards next July, and well beyond: properly cured and stored garlic will keep for six months or more.

Softneck garlic (Allium sativum ssp. sativum ) is the type most commonly found in grocery stores. It tends to produce large bulbs containing randomly scattered cloves of varying sizes. Its pliable stems can be attractively braided after harvest.

Hardneck (Allium sativum ssp. ophioscorodon) varieties produce smaller bulbs bearing fewer cloves more uniform in size. They make up for this dearth by offering a culinary bonus: their bright green stalks, called scapes, are edible. Snip off in late spring and early summer, and enjoy either cooked or raw—their mildly sweet flavor is reminiscent of scallions or chives, but with a hint of garlicky goodness. Left unharvested, the stalks will flower and eventually dry into stalks too stiff for braiding.

The impressive size and mild flavor of elephant garlic (Allium ampeloprasum) make it a kitchen standout, but this popular allium has a secret: it’s not a garlic at all! Although similar in flavor, growth habit, and cultivation requirements, this gentle giant is more closely related to leeks.

Get tips on growing, curing, and storing garlic.

What's Hot in November

rake & leaves
by Barbara Hill

How can I use fallen leaves in my garden?

For gardeners, the delight of fall foliage doesn’t end when the colors fade. Even if your trees don’t provide show-stopping hues, their leaves are nonetheless “gardener’s gold” once they hit the ground. Whether used as mulch, added to a compost pile, or turned into leaf mold, leaves are the ultimate renewable resource, adding vital minerals to soil, improving its water retention and structure, and providing habitat and food for beneficial soil dwellers—all for free!

In hot composting, leaves can provide the “brown” (carbon) part of the equation, joining materials high in nitrogen (the “greens”) to create that nutrient-rich amendment beloved by gardeners and plants alike. Find out how to compost.

Leaf mold might not sound like something we’d want near our plants, but worry not: it’s basically leaf compost, a simple substance that will do great things for your soil. Unlike the much faster, bacteria-driven process of traditional composting, aging leaves have fungi to thank for their senescence. It’ll be a year or so before it’s ready, but if you’re not in a hurry, just create a leaf pile, moisten now and again, and sit back while the magic happens. Find out about leaf mold.

Or skip the pile entirely and simply rake your leaves straight into planting beds! A thick layer added as-is will gradually break down into humus-y goodness while suppressing weeds and retaining moisture; shredding beforehand will speed up the process. Learn about mulch.

What's Hot in December

old tools
by Barbara Hill

After spending a day working hard in the garden, the last thing I feel like doing is cleaning my tools. Is a little rust really so bad?

For fans of “shabby chic,” a patina of rust might be seen as appealingly, well, rustic. But just what is that red stuff? Known scientifically as iron oxide, it's a common compound that forms when metals containing iron are exposed to oxygen and moisture. This is an example of corrosion, an electrochemical process which results in the degradation of the material.

Alloys such as copper, aluminum, and zinc are relatively resistant to this process, and the oxidation that does occur forms a protective coating. For example, when the Statue of Liberty was unveiled in 1886, its copper sheathing was dull brown, like a penny. By 1906, the statue's surface had weathered to its now-iconic green patina, which will prevent further corrosion.

When metals made with iron - like your shovel's steel blade—are similarly exposed, it's a different story. Iron is particularly prone to corrosion, which means, without intervention, a little rust can quickly becomes a lot of rust. Eventually, it's bye-bye, nice, strong steel; hello, crumbly iron oxide.

Bottom line: Experts agree we should indeed clean our garden tools after each use. This helps keep relentless rust at bay, and prevents the spread of weed seeds, insect eggs, and plant diseases. Pairing this with a more intensive cleaning and maintenance regimen when putting away tools for the winter will help assure they'll serve you well for many years to come.

Find out more about the Care and Maintenance of Garden Tools.