- Author: Christina Muller
- Editor: Noni Todd
Diversify with Dahlias!
By Christina Muller Master Gardener
I would like to grow dahlias. Where do I begin? Becky, Morro Bay
Dahlias are showy flowers that encompass a wide variety of flower form, size and color. These tuberous perennials range in size from bedding plants to the stately tree dahlia,Dahlia imperialis, which stretches to a height of 12’-15’. Flowers are incredibly varied, from a petite 2” diameter to the ‘dinner plate’ dahlias with a 12” diameter. Nearly every color except blue is represented and flower forms include single, double, pompon, cactus, and fimbriated, among others.
Plenty of sun and moist, well-drained soil will suit your dahlias. They are most often planted as tubers in the spring but can be grown from rooted cuttings as well. Taller varieties should be staked for support as the stems of dahlias are hollow. These stakes should be placed 5-6” from the tuber at the time of planting. If you didn’t plant dahlias in the spring, they may be available now in nurseries as container plants.
The most common pests are snails and slugs. Hand pick them in the evenings and bait with a product containing iron phosphate which is non-toxic to pets and wildlife. Earwigs can also damage leaves and flowers. A shallow cat food or tuna can with some vegetable oil and soy sauce, bacon grease or tuna oil will attract and trap them. For more ideas on controlling earwigs see the UC pest note: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74102.html
Dahlias are native to frost-free climes of Mexico, Central America and Colombia and are hardy to USDA zone 8. In areas with colder winters, tubers can be lifted in fall after the foliage has withered. Store them in dry peat moss or wood shavings until spring when they can be planted. Named varieties can be labeled directly on the tuber with an indelible pen.
If you would like to see examples of dahlias in person, plan to attend the dahlia show onWed, July 17 at the Mid-State Fair. This is a wonderful chance to see their extraordinary variety and learn about them from both judges and exhibitors.
- Author: Steve McDermott
- Editor: Noni Todd
Make Your Plants Happy With Proper Watering
Q: I go out and water my plants when it gets hot, but they still look frumpy.
From Kay R. Paso Robles
A: You need enough water to get to as much of the root system as possible to make your plants happy. Plants need enough water to properly transport essential nutrients from the bottom of the plant to the very top of the plant. To get water down to the very bottom or edges of your root system, you need to consider the type of soil you have and the depth and spread of your root system. If your soil is primarily clay, such as that found in North County and in San Luis Obispo, the soil holds more water, so it will retain more water. Sandy soil, such as that found near the ocean, holds the least water and drains faster. Sandy soil has a penetration factor of about three times that of clay soil so the water seeps more deeply but does not retain as much water as clay soil. To check the depth of water penetration, dig into the soil and determine how deep the water traveled.
The roots of a plant should have access to water at all times, but avoid over-watering and possibly drowning your plants. Watering should be done relatively infrequently, but deeply. The most effective watering should be done SLOWLY. Quick, overhead watering is not as beneficial to plants. The best technique is the drip method. Installation of drip systems is not necessary, although very convenient, but a dripping hose or inexpensive hose timer may suit your needs.
The root systems of plants vary in depth, so a general rule of thumb is that leafy vegetables and annual bedding plants require 6-12 inches of water. Small shrubs, tomatoes, corn, and cool season turf grass requires 1-2 feet of water. Trees, large shrubs, and warm-season grasses require substantially more to reach deep roots.
Evapotranspiration factors such as temperature, wind, and humidity affect how much water your plants require, so have a chat with your local Master Gardener about your specific needs.
- Author: Terri Sonleitner Law
- Editor: Noni Todd
Smart tips for a great summer garden
by Terri Sonleitner Law Master Gardener
Q. This year has been so hot and dry. What are some things I can be doing in my garden now? Kathy, Paso Robles
- There’s still plenty of time for you to plant heat-loving summer color in your landscape. Try verbena, zinnia, petunia and portulaca. You can also plant impatiens in shady spots.
- July is a good time to feed warm-season annuals, summer vegetables, lawns, roses and subtropical plants.
- Remove spent blooms of flowering plants, including roses, to promote continued bloom. Pinch chrysanthemums back and fertilize them for spectacular blooms this fall.
- Bearded iris can be planted later in the month. Established iris clumps, which are overgrown, can also be divided and replanted.
- In the vegetable garden, cherry tomatoes and squash can still be planted in the North County. In our South and Coastal areas, corn can be planted now.
- Pick fruit regularly and dispose of any fruit that has fallen to the ground.
- Control gophers by trapping. This activity should be continued throughout the year for the best result.
- Inspect all of your garden mulch and add more mulch to areas where mulch is thin. Mulches are very important in summer, they help retain moisture and keep the soil cooler.
- Concentrate on being water wise this summer by closely monitoring your irrigation. Check timers, sprinkler heads, drip lines and emitters, and adjust or replace as necessary. Additional information on irrigation and water conservation tips are available from the University of California Agriculture and Natural Resources Publication 8036: “Water Conservation Tips for the Home Lawn and Garden” which is available online:http://anrcatalog.ucdavis.edu/pdf/8036.pdf
- In this very dry year, be fire safe by removing dead limbs, trees and piles of leaves near your house and other structures. Keep weeds and tall grasses cut down to stubble. Remove any woody vegetation that grows against structures. More comprehensive information on fire safe landscaping is available online in the University of California ANR Publication 8228, “Home Landscaping for Fire”: http://anrcatalog.ucdavis.edu/pdf/8228.pdf
- Author: Kim McCue
- Editor: Noni Todd
By Kim McCue Master Gardener
As the warm weather of summer approaches, our fruit trees become heavy with the season’s bounty. Gardeners all over San Luis Obispo County view the upcoming harvest with excitement, pride and yet maybe with a little anxiety. We live in a climate that is optimal for maximum fruit production of certain varieties, yet controlling the amount of fruit your trees produce can at times be overwhelming. Branches overladen with fruit can break; keeping up with the harvest can be difficult, resulting in wasted, rotten fruit on the ground. Finding ways to consume mass quantities of fruit can be a challenge. Fortunately, the practice of summer pruning can help overcome some of these issues making way for the simple enjoyment of home grown fruit.
Tom Spellman, a professional orchardist with Dave Wilson Nurseries, will be the featured guest speaker at the free Advice to Grow By workshop in the Garden of the Seven Sisters this Saturday, June 22. Summer pruning is one of Mr. Spellman’s specialties and a topic on which he gives presentations throughout California. We are delighted Tom will be sharing his expertise, through both discussion and demonstration, of the whys and wherefores of summer pruning. Tom and Dave Wilson Nurseries donated all the deciduous fruit trees with which the Master Gardeners planted the orchard at the demonstration garden in 2010. It’s exciting to have Mr. Spellman return and actually demonstrate proper pruning techniques on those same trees!
If you have fruit trees, you’ll definitely want to join the Master Gardeners from 10:00 a.m. until noon at the Garden of the Seven Sisters, 2156 Sierra Way, San Luis Obispo. Come prepared with sunscreen, water, and hats as the demonstration portion of the workshop will be held in the orchard.
Have a Gardening Question?
Contact the University of California Cooperative Extension Master Gardeners on Mondays and Thursdays at 781-5939 from 1 to 5 p.m. ; in Arroyo Grande on Wednesdays at 473-7190 from 10 a.m. to noon, and in Templeton on Wednesdays at 434-4105 from 9 a.m. to noon.
Visit the UCCE Master Gardeners Web site at groups.ucanr.org/slomg/or e-mailmgsanluisobispo@ucdavis.edu
- Author: Andrea Peck
- Editor: Noni Todd
Blossom-End Rot
By Andrea Peck Master Gardener
Q. There are dark spots on the bottoms of my tomatoes. What is causing this and how do I prevent it?
A. Like a horror movie, you find yourself walking out to visit your tomato bed. From afar, you see the rosy red fruits of your labor. But, as you get closer you see something. It’s dark and foreboding. It’s yucky. Maybe you emit a silent scream. Maybe you are tougher. But, no matter, the disappointment is palpable. You’ve got rotten tomatoes.
More specifically, you have a case of blossom-end rot.
Blossom-end rot affects the blossom end of maturing fruit. It begins as a small lesion and progresses to a black, leathery blemish. But before your get your “bloomers” in a knot, have no fear, the solution is a simple one.
Blossom-end rot is a physiological disorder related to calcium uptake of the plant. Sandy, high-salt soils and lack of moisture lead to deficiencies in calcium. While some variation exists between plant types, no tomato plant has been found to be resistant to blossom-end rot. Creating a good environment for your tomato plant can eradicate this problem. Amend soil with organic matter to increase its ability to hold nutrients, oxygen and water. Go sparingly when using manures to fertilize soil; they are often high in salts which interfere with calcium absorption. Instead, use fertilizers that are high in phosphorus, such as 4-12-4 or 5-10-10.
To keep your tomatoes firm and juicy, you need just the right amount of water. This is where a “farmer’s consistency” is key. Overwatering or drought conditions impact the plant’s ability to access calcium and form healthy fruit. A drip system makes watering a snap and ensures consistent moisture levels. Set a timer on your drip and spend your time mulling over salsa recipes instead of watering.
Take care when weeding near your tomato plants. Small roots that assist in water and nutrient absorption may get damaged while pulling weeds. Mulching around your plants retains moisture and keeps weeds at bay.
With a little vigilance, you can nip those little “horrors” in the bud.
