Busy Month of May

Tami Reece  Master Gardener

 

May is a month for planting, fertilizing and controlling pests. But don’t be fooled by a late frost!
Plant dahlias and gladiolus for summer color. For annuals you can plant dianthus and pansies. As the nights become warmer you can hang baskets of fuchsias and geraniums. For perennials, shop for summer and fall color with asters, coreopsis, and cornflowers.

Now is the time to check the needs of your lawn. Aerate, feed and overseed to get rid of bald patches. Around midmonth, feed your lawn with an even coat of high-nitrogen fertilizer, watering thoroughly after application.

If you have started your vegetables, now is the time to plant your cucumber, eggplant, melon, pepper and tomato plants. Sow beans, corn, winter and summer squash directly in the ground.

You may want to add some trees and shrubs to your landscape. But remember, it’s important to select the right plant for the right place. A good resource in selecting the perfect tree is http://selectree.calpoly.edu. Give your roses, perennials, deciduous and annual trees and shrubs a good start for the growing season, use either a slow-release fertilizer or compost and mulch the surface area. California natives rarely require fertilizer. After applying fertilizer, always give your plant a thorough watering.  When irrigating, make sure water is not running off your property onto driveways and gutters. Excessive fertilizing with poor irrigation systems could result in polluting creeks and streams.

Also in May, finish any spring pruning on shrubs and trees. Watch for horn worms on your tomato plants and aphids on your roses. Slugs and snails will be prevalent in your garden. To help identify what is eating your plants, visit the University of California Integrated Pest Management Site on the internet or call one of the Master Gardener helplines. Finally, if a late frost does sneak in, make sure to cover any tender plants to ensure your vegetables make it to your table and your flowers bloom through the summer. May is a busy month, but all your hard work will be rewarded.

Please join us on Saturday, April 21 for  a free "Advice to Grow By - Propagation Workshop" from 10:00 a.m. until noon in the Garden of the Seven Sisters, 2156 Sierra Way, San Luis Obispo. 

Plant Propagation Made Easy 

By George Frisch, Master Gardener

Propagating your own plants can be fun, inexpensive and reward you with a variety of species that may not be commonly found in the nurseries.  It's not just for ornamental plants either.  Propagation can provide a greater variety of delicious and unusual vegetables.  

One method of plant propagation we are probably most familiar with involves buying a packet of seeds, sowing them in the ground and keeping them moist, to wake them up.  When we do that with radish, beans, carrots, corn or melons, for example, we are usually well rewarded.  When we try doing the same with peppers, eggplants and tomatoes, we don’t usually fare as well.   That is because some seeds are able to germinate in a wider temperature range.  For example broccoli can germinate between 45F and 85F, while eggplant germinates best between 80F to 90F.  All seeds germinate only when the moisture, soil temperature and sunlight are just right.  We can provide necessary conditions by starting them indoors in containers in a well-draining rooting media on a windowsill.   The best source of information for germinating seeds is found right on the package or visit  cagardenweb.ucdavis.edu.

Division is another easy method of propagation.  Iris reproduce by rhizomes and daylilies spread by fleshy roots, which can be divided.  Division does not only reward you with more plants, but also is a necessary task to maintain iris beds.

Propagation from cuttings, as the name suggests, is the process of cutting a stem from the parent plant and inducing that piece to grow into a new plant.  Many ornamentals and herbs can be successfully grown from cuttings.

I’d like to preserve olives from our tree, but last year each fruit had a little worm in it.  What is this pest?

John B., Templeton

 

By Ann Dozier Master Gardener

Appreciated for their beauty and historical importance, olive trees are a beloved part of many gardens. However, an imported pest has become a severe problem for all growers.

Your crop was probably attacked by the olive fruit fly. This small (about ¼ ‘’ long) fly of Mediterranean origin was first noted in California in1998 and it has spread rapidly. Female flies pierce olives and lay eggs in the fruit. When eggs hatch, larvae (small whitish maggots) begin eating the fruit and when they have grown large enough they pupate and later emerge as adult flies to repeat the process. Olives thus attacked are unsuitable for preserving. If the damage is 10% or less, they may be used for lower grade oil. If you are bringing your olives to a community press, you should contact them first to find out their tolerance level.

To fight olive fruit flies, GF-120 NF Naturalyte Fruit Fly Bait sprays are available at farm supply stores and some nurseries. There are two different traps, Olipe and McPhail-type, which are basically containers filled with a bait of yeast attractant.  These can be found online at Great Lakes IPM (www.greatlakesipm.com) or ISCA Technologies Inc. (www.iscatech.com).  Setting many traps can reduce the numbers of olive fruit flies 30-100%.  But the effectiveness is quite variable.

Commercial growers battling this pest say that backyard growers hinder their efforts by allowing fruit to hang on trees and drop. (The longer olives hang, the more possibility of infestation as flies are more active in warm weather and also more easily bore into ripe olives.)  If you do not plan to use your olives it is good pest management to harvest and dispose of all olives in closed containers.  During flowering season, use a sharp stream of water or  Florel spray to prevent fruit formation. Those planting new trees could look into the several varieties of fruitless olives available.  To find more information on sprays, traps (including a homemade trap) and fruitless trees, visit us online at : http://www.homeorchard.ucdavis.edu , click on fruits & nuts and choose olive.

Question:  I just moved into a house that has been empty for several months.  There are neglected citrus and avocado trees in the yard.  How should I care for them?
Susan Finn SLO
 
Maggie King  Master Gardener

Is it any wonder that we love living on the Central Coast?  In most areas of the county, citrus trees and avocados can be grown with relative ease.  They are beautiful year round.  They produce bountiful quantities of delicious fruit.  Few scents are more intoxicating than citrus blossoms.  Surely, one of our most important gardening tasks should be proper care and feeding of these wonderful gifts from nature.  

Lack of proper nutrients can affect fruit size, flavor, color and abundance. Commercial citrus growers use sophisticated techniques to analyze the nutritional needs of their trees.  For the home gardener these tools are not practical, but there is some basic information that will help us care for our orchards.

The primary nutrient that citrus trees need regularly is nitrogen.  For young, non-fruit-bearing trees, frequent, small applications of nitrogen are recommended.  Once maturity is reached, a citrus tree in the home garden should be fertilized at a rate of about one pound of actual nitrogen per tree per year.

Nitrogen is the primary nutrient need for avocado trees as well.  Again the recommendations vary, but a good application of nitrogen in winter or early spring will enhance flowering and fruit setting.  

Iron Deficiency

Both phosphorous and potassium should be supplemented occasionally.  Deficiencies in iron, zinc and other minerals are relatively uncommon in California orchards, but when present can usually be treated with foliar sprays.  Deficiencies of minerals show up in characteristic changes in the leaves.

Calculating the amount of ACTUAL nitrogen and other nutrients in any given product can be challenging.  With the variation in citrus types, fertilizer formulations, soil types and specific planting locations, a single recommendation for when to fertilize is not possible, but most experts suggest a good dose of nitrogen in late winter or early spring.  As always, the Master Gardeners are happy to answer your questions. The following websites may be helpful as well.
http://ipm.ucdavis.edu/PMG/GARDEN/FRUIT/CULTURAL/citfertilization.html
http://ipm.ucdavis.edu/PMG/GARDEN/FRUIT/CULTURAL/avocadofert.html

For now, Susan, buy a balanced citrus and avocado food at a reputable nursery, follow package instructions, sprinkle the product evenly around the root line of each tree, and water in well.  Your trees will reward you for your care!