Friday, November 20, 2015

Bougies, Italian Cypress, Oxalis, Oranges and Ginkgos: Selected Plant Information Questions for November

Q. I live in Northridge, CA and have Rosenkas (a variety of Bougainvillea that is used as a ground-cover)  that are 2 years old. They have almost no bracts on them, and very long branches (over 4 feet long).  They are planted in the ground - not in containers, 2 feet apart and were planted as a ground cover.  They are hand watered; no more than once a week.  I haven't used any fertilizer, but have amended the soil with homemade compost.   Maybe the compost contains too much nitrogen? The plants do get more than 1/2 day of sunlight.  Could you let me know approx. how many inches should be cut off the branches when I prune them in spring? Some are close to 72" long.
What is the best fertilizer to use and during what season should this be applied?  Also, at what time of the year should they be pruned? 

A. The following things will cause bougainvilleas to favor vegetative growth over producing bracts and flowers:
1.          Too much nitrogen. I have never seen a bougainvillea in need of fertilization.
2.         Too much water. They should be watered no more than once a week after being in the ground for two years.
3.         Too little light. Bougies should be in at least half day full sun.

Remember to prune your bougainvilleas after all danger of frost is past -usually after the middle of March.
Homemade compost is nitrogenous enough to cause them to favor green growth and not flowers.  Suggest cut each plant back by at least ½ in late March.

Cheers,   Frank

Q. I have an 80 year old Italian cypress that is about 75 feet tall.  There is sap running from the tree.  The sap seems to be coming from an old place where a branch was sawed off maybe over 20 years ago.  It is about 8-10 feet from the base of the tree.  I can't tell if the sap is coming from a place higher in the tree and then dripping off from where the branch was, or, if the sap is coming from the place where the branch was itself.  I live in Atwater village, and am under Los Angeles' water restrictions.  Is this something to be concerned with?

A. .If the tree is otherwise healthy I wouldn’t worry about it –do keep an eye on it though.  I would also keep a 4” thick layer of bark mulch underneath the canopy of the cypress. This will help by keeping even the drying of the soil under the tree and it will decompose to help feed beneficial microorganisms that live in its root zone.

Cheers,   Frank

 Q.  I have a marathon 3 lawn.  It has a oxalis infestation.  Can you recommend a good spray or chemical to use?
A. Oxalis thrives in soils that are dryer than is optimal for Marathon grass. Once were off water restrictions and you can water your marathon more frequently the oxalis should abate.  Sometimes the seed load from oxalis infestations make it tough to control even if you water correctly, if that's the case then the judicious use of pre and post emergent pesticides may be necessary.  For a list of herbicides and their use, please refer to the University of California Davis page at:

 Q. Given all the heat is it now too late to feed roses?  Any difference if in pots. 

A. Nix on the rose feeding right now, there's a new pest that loves new growth called the chilli thrip. Same goes for the pots. 

Cheers,   Frank

Q. I have a large dwarf naval orange that is about 20 years old that is producing adequate and tasty fruit.  The tree is losing lots and leaves and large branches are dying off.  Outside of leaf miner damage I don’t see any other signs of pests.  Do You have any suggestions about what to do with it?

A. Wait till after we've had a significant rain (about two months after that actually) and then re-evaluate. Water restrictions here have made conditions rife for significant salt buildup in the soil, which can lead to dying off of branches. A good soaking (2-3 inches of rain) should alleviate that. Do not fertilize your trees until next year.

Cheers,   Frank

Q. Which male ginkgo tree would work best in a front yard in La Crescenta? We need it as a shade tree and would prefer a fast grower (fruitless).  And, do you know of any nurseries that sell your suggestion?

A. I would plant Fairmont or Princeton Sentry.  They're going to grow a bit faster than the wider than tall Autumn Gold variety. You can find them here:

Cheers,   Frank