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Good (but not 'mast') year for acorns

Local oak species producing large crops

Acorns on ground
California oaks are dropping lots of acorns this fall. (Photo: Debbie Arrington)

Got acorns? If you have oaks, it’s likely you’re seeing plenty this season.

“It is a good acorn year!” said restoration ecologist Zarah Wyly, director of urban ecology for the Sacramento Tree Foundation. “Finally, something went well in 2020.”

Although acorns are plentiful this fall (making countless squirrels very happy), this harvest doesn’t quite measure up to what’s known as a “mast year.”

“I don't know if it is quite up to the ‘mast year’ level of acorn madness,” Wyly observed. “I have been describing this as a good acorn year and nothing more. My experience with past mast years – I feel I have experienced two in the last 15 years of oak watching in the Sacramento area – was that pretty much every oak tree had a crop. While there are lots of acorns available, it isn't quite at that level.”

Wyly oversees acorn collection for the foundation, which annually harvests acorns to grow native oaks for replanting. A good acorn crop helps.

“I have a group of 45 human squirrels out gathering it up to grow the next generation of native oaks,” she said. “This is always easier and more fun when acorns are easier to find.”

How many acorns will they harvest?

“Our volunteer acorn harvesters gather between 7,000 to 10,000 acorns from local native oaks each year depending on our planned seed needs,” Wyly said. “Since we started doing this with volunteers in 2010, we have harvested over 100,000 acorns!”

Rarely do all local oaks have big harvests at the same time. Part of the reason: Not all acorns ripen at the same pace.

“Locally, we can have oaks having a good year and some having a bad year,” Wyly explained, “as our valley oak ( Quercus lobata ) and blue oak ( Quercus douglasii ) produce ripe acorns over about eight months whereas our local interior live oak ( Quercus wislizeni ) produces ripe acorns over about 20 months. So, the crop we are seeing right now was the pollen making us sneeze this March and March 2019 respectively.

“Differences in these years, such as very rainy weather, can impact pollination and the subsequent acorn crop,” she added. “From what I have seen, all three of these local native species are having a very good year this fall.”

Non-native oaks are having a good crop, too, but that’s more common for those species.

“As for our non-native oaks, some of them are much more reliable acorn producers,” Wyly said. “For example, the cork oak ( Quercus suber ) and the holly oak ( Quercus ilex ) seem to have acorns every year and in large number. I imagine this has to do with species differences including possibly the ability to self-pollinate and/or impacts from urban living where they receive more water than they might in their natural home (Europe). There isn't a ton of research on this.”

As for what so many acorns may portend? According to folklore, an abundance of acorns signals a bad winter ahead. The Old Farmer’s Almanac recently asked readers for their acorn experiences. Judging by the responses, most of the country is in for a cold winter.

Or a lot of happy squirrels.


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Dig In: Garden Checklist

For week of March 26:

Sacramento can expect another inch of rain from this latest storm. Leave the sprinklers off at least another week. Temps will dip down into the low 30s early in the week, so avoid planting tender seedlings (such as tomatoes). Concentrate on these tasks before or after this week’s rain:

* Fertilize roses, annual flowers and berries as spring growth begins to appear.

* Knock off aphids with a strong blast of water or some bug soap as soon as they appear.

* Pull weeds now! Don’t let them get started. Take a hoe and whack them as soon as they sprout.

* Prepare summer vegetable beds. Spade in compost and other amendments.

* Prune and fertilize spring-flowering shrubs after bloom.

* Feed camellias at the end of their bloom cycle. Pick up browned and fallen flowers to help corral blossom blight.

* Feed citrus trees, which are now in bloom and setting fruit.

To prevent sunburn and borer problems on young trees, paint the exposed portion of the trunk with diluted white latex (water-based) interior paint. Dilute the paint with an equal amount of cold water before application.

* Cut back and fertilize perennial herbs to encourage new growth.

* Seed and renovate the lawn (if you still have one). Feed cool-season grasses such as bent, blue, rye and fescue with a slow-release fertilizer. Check the irrigation system and perform maintenance. Make sure sprinkler heads are turned toward the lawn, not the sidewalk.

* In the vegetable garden, transplant lettuce and kale.

* Seed chard and beets directly into the ground.

* Plant summer bulbs, including gladiolus, tuberous begonias and callas. Also plant dahlia tubers.

* Shop for perennials. Many varieties are available in local nurseries and at plant events. They can be transplanted now while the weather remains relatively cool.

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