Saturday, July 23, 2011

How to Tell the Boys from the Girls (Squash, That Is)

It's a question that is asked a lot in the late spring and early summer by vegetable gardeners: "Why am I not getting any squash? After all, there are flowers on the plant. And any fruit that does develop tends to fall off."

According to retired UC Vegetable Specialist Hunter Johnson: "Squash, melons and cucumbers have a flowering habit which is unique among the vegetable crops. They bear two kinds of flowers, male and female, both on the same plant. In order for fruit set to occur, pollen from the male flower must be transferred to the female flower. The pollen is sticky; therefore, wind-blown pollination does not occur. Honeybees are the principal means by which pollen is transferred from the male to the female flower. Other insects cannot be depended upon for pollination."

Not only will a shortage of bees result in poor pollination of your squash, it may only be partial pollination. This results in misshapen fruit, low yield and the demise of immature fruit.

Rain, low light, or cold and hot temperatures can limit bee activity. Also, avoid using insecticides that are harmful to bees; it will say so on the product label.

There are other reasons why you may be having problems with your summer squash production: not enough sunlight (plant them in full sun) and planting too early in the season. Squash need very warm soil temperatures to thrive, ideally 70-95 degrees (F). Here in the lower elevations of California, sow seeds directly in the garden in May.

Another reason for early season squash fruit failure, according to Hunter Johnson: "All of the early flowers are males. Female flowers develop somewhat later and can be identified by the miniature fruit at the flower base. However, In hybrid varieties of summer squash,  the first flowers to appear are usually females, and these will fail to develop unless there are male squash flowers -- and bees -- in the nearby area."

But lack of bees is the primary reason for poor fruit set in squash, melons and cucumbers.

If you have a shortage of bees, consider putting in bee-attractive plants

So, what's a bee-less gardener to do? Pollinate by hand!

Transferring the pollen from the male flower to the stigma inside the female flower is easy to do, if you follow a few guidelines:

Know your squash flowers. The male flower has a long slender stem, along with a penis-like structure in the inside of the flower. The female flower has a very short stem, along with a miniature fruit (the ovary) at the base of the flower.

 Ronde De Nice Zucchini Flowers. Male on the left, female on the right.

Inside the zucchini flowers, male and female. Note the cute yellow condom on the male.

You could break off the petals of the male flower and then use a small artist's brush to transfer the yellow pollen from the male squash penis (OK, OK, it's technically a "stamen") to the stigma of the female flower.

American River College Horticulture Professor Debbie Flower has an even easier way: "Just peel away the male flower petals, cut off the flower and then twirl the male flower inside the female flower."

The best time to do this? In the early morning. Use only freshly opened flowers; they're only "in the mood" for one day.

What about cross pollination among these cucurbits? Not a worry, unless you save seed for next year, says Johnson: "A common misconception is that squash, melons, and cucumbers will cross-pollinate. This is not true; the female flowers of each can be fertilized only by pollen from that same species. Varieties within each species, however, will cross-pollinate. Thus, zucchini squash will cross with crookneck or acorn squash, and similarly among varieties of cucumber, and among varieties of muskmelon. When more than one variety of a particular cucurbit is grown in the garden, they will readily cross, and seed saved from these plants will produce fruit which will be different from either of the parents."

Sunday, July 17, 2011

Corpse Flower Growing at Roseville High School

 A Sacramento-area high school is about to take on a very distinctive, and exclusive, aroma in their greenhouse.

C.J. Addington, biology teacher at Roseville High School passes along the information:

"You may recall that last month there was a blooming of the huge and rare "Titan Arum" flower (Amorphophallus titanum) at UC Davis. 
Ernesto Sandoval of UC Davis Tends to Ted the Titan

Also known as the 'Corpse Flower' because of its pungent rotten-meat odor, this exotic giant bulb from Indonesia is difficult to grow and bloom, often taking ten years or more to reach flowering size. You normally only see them at large universities and botanical gardens with the staff and resources to nurture them for years on end. 

However, we are thrilled to announce that Roseville High School, right here in the Sacramento metro area, has now successfully also brought a Titan Arum to bloom, and we have been told that we are the very first K-12 public school anywhere to achieve this feat. 
CJ Addington and a young Tiger the Titan

We have been growing two of these plants in the greenhouse on the RHS campus, and realized this week that our ten year old specimen is making its very first bloom ever. We have decided to name it "Tiger the Titan" after our school mascot, and will be opening our greenhouse for a public viewing (and smelling!) when the flower opens, which we estimate will happen on or around July 25 or 26. 

We will be posting information on our school website ( starting Monday the 18th about how and when the public may see our prize flower, but in the meantime, folks can follow the progress of the bud at our Flickr page ( ). 

The Titan Arum blooms at UCD are always a big attraction, and we believe that the first Titan bloom at a high school is a neat twist on these fascinating organisms. I think that it's pretty cool that a lowly suburban high school like us has now achieved what only universities have pulled off before."

Congratulations to Roseville High, not only for raising the Titan Arum, but also for instilling an interest in plants among their students!

(and thanks to Carri Stokes of the Between the Limes blog for the pictures of Ted the Titan at UCD)
Amanda Poletti, Carri Stokes and Kat Chaussee admiring Ted the Titan at UCD last month

Wednesday, July 6, 2011

Wilting Plants? Check Soil Moisture Before Watering

Improper watering is the number one cause of plant failure. Knowing how wet the soil is at the root level can help you keep your plants healthy

Keep in mind: different plants have different watering needs. Learn those needs, then group plants together with similar watering requirements when designing your landscape. The Sunset Western Garden Book is a good source for that information.

Signs of not enough water at the root level of plants: 
Wilted leaves in the morning. Wilted leaves in the afternoon.
Wilted leaves in the evening.
Red-brown margins of leaves.
Premature fall color of leaves.
Growth reduction.
Leaf drop.
Branch dieback.

Signs of too much water (also called aeration deficit) at the root level of plants:
The soil has a foul smell, like rotten eggs.
Soil is a blue-gray color.
Yellowing, wilting and/or dropping of leaves.
Limited new growth.
Small, corky outgrowths on the undersides of leaves.

Be warned, though: sometimes, symptoms of overwatering and underwatering can be the same (such as leaf wilting). And, symptoms of soil water problems may actually be another problem...that was caused by your watering regimen! Root rots, for example, thrive in saturated soils.

Frequent, light watering leads to shallow rooting, increasing the chances of plant problems.

Regarding droopy leaves on a hot afternoon: there are two schools of thought.
One school says plants conserve moisture on a hot afternoon by allowing their leaves to sag.

The other school says: don't believe them. Drooping leaves are usually indicative of a lack of water from the root zone. "Large, thin leaves, common in many of ornamental, annual and vegetable species, do not conserve water," writes Washington State University Horticulture Professor Linda Chalker-Scott. "Tomatoes, zucchini and black-eyed Susans...are not water conservers. Chronic wilting of these and others can eventually cause leaf tip and margin necrosis (or tissue death). It also reduces growth, so that your yield of tomatoes, zucchini and black-eyed Susans will be decreased."
She advises applying a layer of mulch around those plants to help conserve water. 

Also, check the moisture at the root level before watering.

To determine the amount of water at the root level:

• A day or two after watering, dig down 8 to 10  inches with a trowel or small shovel, near the drip line (outer canopy) of the plant. Doing this in two or three spots would be more helpful.

• At that depth, grab a handful of the soil. Squeeze that handful. If it is muddy and watery, reduce your watering for plants that require regular (but not frequent) irrigation. If it is so dry you cannot form a clod in your hand (it turns to dust instead), increase your watering (for those plants that require moderate amounts of water).

• If you can form a dirt clod in your hand, yet break it apart with a little effort, that is probably the correct soil moisture for your plant.

• Steve Zien, owner of the Citrus Heights-based organic landscaping consulting service, Living Resources, recommends the use of a soil sampling tube to determine the moisture at root level. "Just press the tube down six to eight inches into the soil after you are done watering," says Zien. "When you bring it back up, the open slot along the side of the tube will let you see if the soil at that depth is wet, moist or dry. Adjust your watering time so that the soil sample is moist, not too wet or dry."

• An easier, but more unreliable way to measure the water content of the soil: purchase an inexpensive (under $10) moisture meter, available at most nurseries. Test its accuracy by putting its probe into a glass of water. If the probe does not read "wet", choose another. Expect it to function for only a year or so.

Battery operated moisture meter probes may set you back a few more dollars, but in my experience - with proper care (clean them after each use, don't leave them outdoors) - they will last many years.


• Extended, infrequent, slowly applied irrigation is the most efficient watering method. Soaker dripline or drip irrigation systems work best. Here in the Central Valley, foothills and Bay Area, run them for 3 to 6 hours at a time, twice a week, in the summer. This is only a guideline to get you started. Adjust that timing to your particular soil type and plants.

• And, don't forget: add more drip emitters and drip lines as the plant grows, especially for trees and shrubs. Make sure to get water to the outer canopy of the plant (and beyond) where the roots travel.

How much water does your lawn need? 
Some tips from the UC Integrated Pest Management Website:

• Avoid planting turf species that require frequent watering, such as bluegrass or ryegrass.
• Design your landscape to minimize water runoff onto hard surfaces and into storm drains.
• To reduce runoff, install non-irrigated buffer areas, which include water-efficient plants or permeable features, next to sidewalks or on slopes.
• Aerate heavy or compacted soils, so water can easily move down to reach grass roots.
• Install an irrigation system that you can adjust to properly water areas of your landscape that have different requirements.
• Water only when your lawn needs it.
• Water requirements vary according to turf species, location, and month of the year.
• Most lawns need water when the top 2 inches of soil have dried out.
• Shady and sunny areas and different soil types will have different water requirements.
• Deeper, less frequent watering is best for most lawns. Water only 2 to 3 times a week.
• Make sure your sprinkler system isn’t producing runoff, especially on slopes. If you see runoff, use shorter watering times and repeat the cycle to allow time for the water to move into the soil.
• Water early in the morning when evaporation and wind are minimal.
• Adjust your watering schedule seasonally, and shut off your irrigation system during rainy weather.

And, the video: How Much Water Do Your Plants Need?

Friday, July 1, 2011

Harvest Fruits by Look and Feel, Not the Calendar

The calendar says July (or, in gardening parlance, "Fruit Pickin' Time!"). But our cool, wet spring has slowed the harvest of the backyard deciduous tree fruits. One taste would let you know that this is definitely not a typical year. 

Flavor Supreme Pluot, Fully Ripe

Even though the Flavor Supreme pluot crop (a cross between a plum and an apricot) is usually ready by now, a sample bite might cause you to spit it out. And it did.

 It's easy this time of year to give in to the uncontrollable urge to pick, eat and wince. How can you tell when fruit is ready for harvesting? One way is to download the fruit harvest chart from Dave Wilson Nursery. The problem with relying on that chart: your location, and weather conditions, can vary from the suggested harvest times on that chart. Here's a sensory guide for the most common fruits and berries grown in backyard gardens around here. This year, because of the cool, wet spring, you can add a few more weeks to the harvesting schedule for each variety.

Suggested dates apply especially if you live in the low-lying areas of Northern or Central California. 
   Apples - Harvest varies from July to October; look for bright red color or a delicate blush overlaying the yellow base. Fruit should release easily from tree with the stem intact.
   Apricots - Mid-May through early July; color changes from dull greenish-orange to bright yellow-orange; Flesh is tender and yields to gentle hand pressure.
   Blackberries - Mid-June to early August; color changes from red to black; berries release readily, are soft with tender skin and are easily damaged. Place in refrigerator as soon as possible.

Cherries - Mid-May through mid-June, depending on the variety. Net the trees at the first sign of birds eating the fruit. Sample a cherry every few days until they pass your taste test. Keep the stems attached when picking to avoid damaging the fruit. Snipping instead of plucking will keep next year's fruit spurs intact.

 Figs: two harvests, usually: mid-summer and early fall. Harvest figs when their necks wilt and fruits droop.
  Mulberries: Information from the California Rare Fruit GrowersWhite and red mulberry fruits (and hybrid fruits) are ready for harvest in late spring. The fruit of black mulberries ripen in summer to late summer. The fruits of white mulberries are often harvested by spreading a sheet on the ground and shaking the limbs. A surprising quantity can be gathered from a comparatively small and young tree. Black mulberry fruits are more difficult to pick. As the berries are squeezed to pull them loose, they tend to collapse, staining the hands (and clothing) with blood red juice. Unwashed the berries will keep several days in a refrigerator in a covered container. The ripe fruits of the black mulberry contain about 9% sugar with malic and citric acid. The berries can be eaten out of hand or used in any way that other berries are used, such as in pies, tarts, puddings or sweetened and pureed as a sauce. Slightly unripe fruits are best for making pies and tarts. Mulberries blend well with other fruits, especially pears and apples. They can also be made into wine and make an excellent dried fruit, especially the black varieties.

 Nectarines - June to September; most common skin colors start out as yellowish-orange and mature into an orange, red or reddish-pink color; flesh is usually yellowish with red tinge near the pit. Cool immediately.
 Peaches - Mid-May to September; same conditions as nectarines. Newer varieties may be bright red in color with an orange tint.
  Pears - July to October; ready when fruit is full size but still green in color.  Ripen harvested fruit in a cool place (50-70 degrees) until color turns light yellow-green.

Plums, Pluots - June to September; color may be solid or mottled red, dark-blue or purple. Flesh is firm yet yielding to gentle hand pressure. Cool fruit immediately.

 Raspberries - June to September; color is red to black, depending on variety. Flesh should be soft, aromatic, juicy; should release easily from cap.
 Table grapes - August to October; Fruit turns from green to reddish-amber, black, bluish, or golden yellow depending on variety. The berries will tend to crush easily and shatter when ripe.