By Mary Helen Seeger, Four Winds Growers *
People often ask us about frost protection and other citrus winter care questions, so here are a few tips.
1. Check foliage. If not deep green, fertilize! (A 3 Nitrogen- 1 Phosphorous- 1 Potassium ratio is best, plus trace minerals) Contrary to advice given for years, recent experiments confirmed that well-fertilized trees are healthier and more resistant to cold weather damage. Even if new growth is produced in the fall, and then is damaged by frost, overall the tree is healthier. We recommend the following fertilizers: Maxsea Acid w/Iron and Zinc, Organic EB Stone Citrus Food, Greenall Citrus and Avocado, GroMore Citrus Grower Blend
2. If insects such as scale or aphids are found on the trunk or foliage, there are several alternatives. Hose down the
plant with plain water or use an insecticidal soap or horticultural oil.
3. Wait until spring to do any major pruning. We prune every season but winter.
4. Cold weather fruit harvest: There is no need to panic with projections of a few hours of temperatures in the high 20s. These brief dips will not damage citrus. Meyer lemons and all types of lime are best harvested before temperatures drop to 30 to 32 degrees F consistantly. Eureka and Lisbon Lemon have thicker skins and can hang on the tree without damage to 26-28 degrees F. If you have a bumper crop, freeze some juice in ice trays, store the cubes in the freezer for later use in drinks or salad dressings.
Other fruits: Owari Satsuma Mandarins and Dancy Tangerines are beginning to ripen in late November. These fruits can tolerate dips into the upper twenties without a problem. Navel oranges are best left on the trees to sweeten until January although yo will find them appearing in stores earlier. Minneola Tangelos are beginning to get their gorgeous orange-red color in late November, but they won’t be sweet until March or April.
Potential cold damage is a combination of time and temperature factors. Prolonged temperatures in the teens can cause much damage. Microclimates can be sought in looking for planting sites. Reflected or retained heat from warm walls or cement walks will provide protection. Fences will prevent additional stress from cold winter winds. Limes and Lemons are the most sensitive, needing some winter protection in colder locales; other citrus are fairly hardy once established.
To protect against cold damage, use Wilt Pruf and Harvest Guard Row Cover.
5. Here are some hints if a hard freeze is predicted:
A. Make sure all plants, especially those in containers, are well watered. If dry soil freezes, it will pull moisture from the roots, causing them damage. If the soil is moist, the soil can freeze without harming the roots.
B. Use an anti-transpirant such as Wilt Pruf once a month or just prior to cold weather. This will give the foliage 4 extra degrees of protection as well protect against damage from desiccating winds.
C. Christmas lights hung in citrus have proven effective at keeping the cold at bay even with temperatures in the teens. Landscape lighting at the base of the trunk and portable shop lights are also beneficial.
D. Insulating crop blankets or micropore plastic can give some protection. Tarps and plastic are not as effective. If used, they are best with a frame so the material doesn’t touch the foliage.
These Four Winds Citrus are listed in order of cold hardiness:
- Kumquats- can tolerate the low 20s
- Owari Satsuma Mandarin
- Minneola Tangelo
- Navel Oranges
- Blood Oranges
- Clemantine Mandarins
- Grapefruit
- Spring/summer ripening oranges ( Trovita, Lane Late, Valencia)
- Spring/summer ripening mandarins (Kinnow, Kara, Murcott)
- Dancy Tangerine
- Lisbon Lemon
- Eureka Lemon
- Meyer Lemon
- Calamondin
- Bearss Lime
- Limequat
- Mexican Lime- will drop foliage at 32 degrees
For more citrus care and culture, speak to a Sloat California Certified Nurseryperson or staff member. You can also visit www.fourwindsgrowers.com
*Used with permission