September Gardening
It may be a lot cooler outside, but our Arizona gardens are still going strong. There are a lot of things we can do for our plants this month to get them through the winter and prepare them for the coming year…
What to Plant in December
- Cold hardy trees and woody shrubs
- water every 2-3 weeks through the winter, when the top portion of the soil is dry
- Bare root roses and deciduous fruit trees
- Transplant established perennials, frost hardy shrubs, and native woody shrubs
What NOT to Plant in December
- Wait until spring to plant anything that is sensitive to cold temperatures
What to Fertilize
- Winter veggies can be fertilized with a side-dressing of compost or a granular slow-release fertilizer
- Overseeded lawns can be fed with a balanced lawn fertilizer
- Blooming Christmas cactus can be fed with a water soluble fertilizer at 1/4 strength recommended for houseplants
Prune, Divide, and Conquer
- Deciduous trees and shrubs can be pruned when they’re fully dormant, but they’re probably not quite there yet
- Test for dormancy by making a small cut at the end of a branch. If any sap comes out, it’s not quite dormant, and you should wait to prune
- Ornamental grasses that are completely dormant can be cut back to 8-8 inches above the soil level
- Resist the urge to prune frost-damaged stems off of cold-sensitive plants. Leaving the browned leaves in place will help prevent further frost damage
For the Fruit Trees
- Tangelos, navel oranges, mandarins, lemons, and limes are continuing to ripen this month. Taste test regularly for sweetness and juiciness, and harvest when they are ready
- Lemons will keep well on the tree until March, so feel free to pick as needed
- Be ready to protect your citrus trees from freezing temperatures. Some types of citrus are more sensitive to frost than others. Check the cold hardiness of your particular tree on our Citrus Management Page (scroll to the bottom of the page for hardiness listings)
- Large Christmas lights (not LED) can be strung in the tree to help heat accumulate under a frost cloth
- If we get extended hours of subfreezing temperatures and you suspect that your citrus fruit has frozen, pick the fruit immediately and get all the juice you can squeeze
- If you plan to treat fruit trees with dormant oils (such as NEEM) for pest control, December and January are the months to do so
Water Wisely
- Wait until the top inch of soil is dry before watering
- water as deeply as you normally do (for the same amount of time), but less frequently
- Slow, sustaining winter rains may replace the need to irrigate (if we’re lucky)
- Annual wildflower seedlings should be watered weekly
- Dormant bermuda lawns will need to be watered once this month to a depth of 6 inches
- Overseeded lawns can be watered every other week to a depth of 4-6 inches
- Roses can be watered every 7-10 days
- Established perennials can be watered every 3 weeks if dormant, and every other week if still actively growing
- Established trees and citrus trees need one deep irrigation this month
- Deciduous fruit trees can be watered every 3 weeks
- Plants growing in containers can be watered as needed. Check the soil before watering to make sure that it’s dry!
General Chores
- Be ready to cover plants when a frosty night is expected. Temperatures of 28° F or lower can be damaging to frost sensitive plants
- Tips of frost-sensitive columnar cactus can be temporarily protected with styrofoam cups
- If winter rains bring winter weeds, pull them out before they become problematic
- Insect activity is generally down, but keep an eye out for the beginnings of an infestation. They are much easier to control with just water or soap when their numbers are small.
- Save fallen leaves that you’ve raked to use as mulch, or add them to your compost pile
- Be sure to keep mulch from building up against woody stems or tree trunks
- Don’t dispose of ash from your fireplace or fire pit in the garden; our soil pH is already high, and adding ashes will make the problem worse
- If you’re considering a living Christmas tree, pick one that can be planted in the garden. Afghan pine, Aleppo pine, and Arizona cypress are all great choices for Arizona gardens.
Did we forget to add something that is on your December gardening checklist? Leave a comment or email amy.civanonursery@gmail.com to let us know!
Sources: University of Arizona online publications, Arizona State University online publications, Desert Botanical Garden website, Tucson Botanical Garden website, Gardening in the Deserts of Arizona by Mary Irish, Arizona Master Gardener Manual
