Citrus - Knowledgebase Question

Gualala, CA
Avatar for SGRousseau
Question by SGRousseau
October 8, 2005
Dear Monrovia:

I am looking for an excellent juicing orange for USDA zone 9. The Moro Blood Orange I bought through one of your retailers years ago is a non-producer and very slow growing, so it is time to relegate the Moro to a container and plant another variety of orange that will grow better and produce oranges.

Fast growth or, better yet, a larger specimen is critical as said tree needs not only to produce delicious oranges, but block the view of an unsightly shack on my neighbor's property.

Can you deliver a 6-8+ foot tree to one of your retailers in my area? If so, which orange would you suggest for the job? Cara Cara Pink Navel Orange, Marrs Valencia, Trovita, Campbell Valencia, Washington Navel?? The Trovita or Washington sound the most reliable for relatively cool summers found in my area - on border of coastal & inland zone.

Anxiously awaiting your advise.

Regards, Sean Gaynor-Rousseau

Answer from NGA
October 8, 2005
It can be difficult to find just the right orange to grow in your region. Subtropical and Mediterranean climates, like those found in parts of California, feature seasonal changes in daylength plus some considerable day/night temperature fluctuations. These climate factors produce citrus with the brightest fruit color, smooth skin, and an optimal blend of sweetness and acidity, giving it the richest, fullest flavor for fresh eating. The main disadvantage of citrus grown in these conditions is the danger of cold and frost. In cool coastal climates, sweet citrus (oranges, Mandarins, and grapefruit) may have a lower sugar content than desirable.

Especially in cool or marginal growing areas such as yours, choosing successful planting sites for citrus on your property will involve some common-sense use of microclimates and cultural practices.

By using south-facing slopes and even south sides of buildings and fences, gardeners can maximize heat absorption. Planting at the top of a south-facing slope and avoiding low spots will reduce the risk of frost damage. Remember that, like water, cold air seeks its own level, i.e., it flows downhill and accumulates in low-lying areas called "frost pockets."

To increase the heat available to citrus in the summer, choose a wind-free site.
Dark background surfaces (walls, buildings) and dark mulches absorb and re-radiate more heat than light-colored surfaces.

Culturally, raised beds warm more quickly than compacted soil. Minimize nitrogen inputs from mid summer onward to reduce frost-susceptible new growth in fall and winter. Higher moisture levels in the soil also help reduce frost damage.
There may be times when some sort of frost blanket makes the difference between life and death for a citrus tree.

With that said, here are my suggestions:
Washington Navel - A chance mutant from a seeded fruit in Bahia Brazil in 1860s introduced to Riverside, California (where one of the three parent trees still lives) in 1873, thus starting the citrus industry in California. Ripens December - May. It is the classic eating orange. It fruits poorly in high heat of desert and only adequately in cooler areas. It reaches its peak in interior valleys of California.

Trovita - A navel-less seedling of the Washington navel, it reportedly does better on the coast.

Valencia - The classic juice orange. A very vigorous, round-headed tree. Better sliced than peeled for eating out of hand. Fruit holds on the tree almost endlessly-up to six months. This ability makes it easier to sweeten up in cool growing areas than navels. Ripens April - September.

Best wishes with your new tree!

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