Sacramento Digs Gardening logo
Sacramento Digs Gardening Article
Your resource for Sacramento-area gardening news, tips and events

Articles Recipe Index Keyword Index Calendar Twitter Facebook Instagram About Us Contact Us

Know the chill factor before you plant


Fuyu persimmons bear more fruit when there's more chill.
(Photo: Debbie Arrington)
Chill hours are a key to success for many fruit trees and shrubs




It’s nature’s cue to take a nap. Lower temperatures in fall signal many plants to wrap things up, drop their leaves and drift off into dormancy. They need to rest.

But it’s the winter cold – measured in chill hours – that really makes a difference in plant performance in the year ahead.

Autumn, which officially starts Saturday, is a wonderful time to plant deciduous trees, shrubs and perennials in Sacramento. They appreciate the lingering warmth of summer while putting down roots and gearing up for a big spring.

Chill hours are an important factor when choosing which varieties to plant. Some need more chill than others.

Chill hours are that kiss of cold that cues blooming and fruiting in a wide range of plants, such as apples, almonds, blueberries, peaches, grapes, persimmons and peonies. Measured from Nov. 1 through Feb. 28 or 29, that chill time is roughly the number of hours below 45 degrees each winter (but above freezing). The total subtracts hours above 60 degrees, which offset the chill effect.

According to the UC Cooperative Extension master gardeners, Sacramento gets on average about 600 chill hours each winter, some communities much more. The Fair Oaks Horticulture Center, home to the Sacramento County master gardeners, recorded 792 hours below 45 degrees last winter; 762 were in that sweet spot above 32 degrees. That also means the Hort Center experienced only 30 hours below freezing.

Chill hours can fluctuate widely, which often accounts in crop changes, too. For example, the Fair Oaks station measured 1,028 chill hours in the winter of 2012, but only 480 in 2014.

The University of California’s Fruit and Nut Research and Information Center developed a very handy set of online tools to calculate chill hours. Its database includes both cumulative chill hours during the current season as well as wealth of historical information. Find it here:
https://bit.ly/2NPObh0 . Or got to the center’s website, http://fruitsandnuts.ucdavis.edu/ , and search for “chill calculator.”

Comments

0 comments have been posted.

Newsletter Subscription

Sacramento Digs Gardening to your inbox.

Taste Fall! E-cookbook

Muffins and pumpkin

Find our fall recipes here!

Thanks to Our Sponsor!

Cleveland sage ad for Be Water Smart

Local News

Ad for California Local

Garden Checklist for week of Dec. 8

Make the most of dry weather while we have it this week. Rain is returning.

* Rake leaves away from storm drains and gutters. Recycle those leaves as mulch or add to compost.

* It’s not too late to plant something. Seed wildflowers and plant such spring bloomers as sweet pea, sweet alyssum and bachelor buttons.

* Trees and shrubs can be planted now, especially bare-root varieties such as fruit trees or rose bushes. This gives them plenty of time for root development before spring growth. They also benefit from winter rains.

* Plant bare-root berries, kiwifruit, grapes, artichokes, horseradish and rhubarb.

* Set out cool-weather annuals such as pansies and snapdragons.

* Lettuce, cabbage and broccoli also can be planted now.

* Brighten the holidays with winter bloomers such as poinsettias, amaryllis, calendulas, Iceland poppies, pansies and primroses.

* Keep poinsettias in a sunny, warm location; bring them inside at night or if there’s rain.

* Plant garlic and onions.

* Prune non-flowering trees and shrubs while they’re dormant.

* Clean and sharpen garden tools before storing for the winter.

* Mulch, water and cover tender plants to protect them during threat of frost. Succulent plants are at particular risk if temperatures drop below freezing. Make sure to remove coverings during the day.

* Rake and remove dead leaves and stems from dormant perennials.

Taste Spring! E-cookbook

Strawberries

Find our spring recipes here!

Taste Summer! E-cookbook

square-tomatoes-plate.jpg

Find our summer recipes here!

Taste Winter! E-cookbook

Lemon coconut pancakes

Find our winter recipes here!