When the winter rains end, it’s time for gardeners to focus on providing spring and summer edibles with the water they need to grow and produce. While hand watering may be the simplest way to adjust watering to the needs of individual plants, it’s not the most efficient means for getting the right amount of water to an entire garden.

Drip irrigation has proven to be the best option for home gardeners. It is particularly suitable for edible gardens because it delivers the water at the soil level and avoids water on the plant leaves which can lead to problems with mold and mildew. 

Drip irrigation is also waterwise, reducing loss by evaporation and runoff and maintaining a desirable balance of air and water in the soil through slow application of water to plant roots.

What can go wrong with drip irrigation?

Whether installed by professionals or as a do-it-yourself project, drip irrigation requires routine maintenance. It’s recommended that the lines be checked monthly when the system is operating. It is especially critical when the drip irrigation is first turned on in the spring. Here are some common problems to look for:

• Leaks. The dreaded geyser is a sure sign that there is a break in the line somewhere. It could be a dislodged emitter or a damaged line. Thirsty rodents like to chew on the tubing and lines can be unintentionally broken by shovels and spades.

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Finding a wet spot where there is no emitter can signal a problem in the supply line. If the line is buried, it will take some digging to find the leak. This was a recent problem in the Edible Demo Garden. The drip irrigation was installed some time ago and it was unclear which lines led to which bed. The search for this particular leak is still continuing.

• Blocked lines and emitters. Lines may get clogged, and emitters can be plugged by debris, mineral buildup, and algae. Pinched lines, especially the smaller feeder lines, can also be a problem. Periodically walking the circuit and checking flow from the emitters while the system is running is a good way to spot irrigation problems before plants start showing signs of distress.
• Low water pressure. Drip irrigation operates at 15-25 pounds per square inch (psi) which is much lower than sprinkler systems which can require up to 50 psi, and household systems running at 50-80 psi. A pressure regulator is needed to reduce the incoming household pressure to that for which the drip systems are designed. However, pressure in the lines can be lowered further by elevation gain, friction in the tubing, and long line lengths. It is recommended that 1/2” supply lines be limited to 200 feet in a single zone and the number of one gallon per hour emitters per line not exceed 200. If a drip emitter at the end of a line is not delivering sufficient water, it could be a low-pressure problem.

Fixing drip problems

With the right supplies, many common irrigation problems can be easily fixed. An emergency drip repair kit should include spare flow emitters of different sizes, connectors (both straight and elbow), line plugs, end caps, and tubing. It’s also handy to have a tool for cutting tubing, a punch to make holes in 1/2” line, and metal staples for securing the lines. The same supplies are useful when drip lines need to be added for new plants.

Lines can be flushed to remove debris, and clogged emitters can be cleaned or replaced. Small holes in lines can be plugged. Larger damaged sections in lines can be removed and connectors used to join the undamaged sections.

A water pressure test gauge, available at hardware stores, is helpful in determining if the pressure in the drip system is in the right range. Low pressure problems due to overly long lengths of supply line or too many drip emitters might involve changing the drip line layout or adding another zone to the system.

Controlling drip irrigation

Drip systems require control valves to direct water into the system. These are generally automated with an AC or battery powered controller/timer that makes it easy to set irrigation frequency and duration. These devices range from simple timers to more complicated “smart” controllers. All these devices include the option to run the system manually, allowing gardeners to conduct their periodic system maintenance checks.

Click here for more information on irrigation systems.

After an especially busy summer and fall harvest season, it was time to consider what to plant next in the Edible Demo Garden. In Marin it’s possible to grow vegetables year-round and there are plenty of winter crops such as cabbage, cauliflower, and onions to select. However, another option is to not plant anything during the winter months and give the garden beds some time to rest and rejuvenate. This puts the focus on caring for the soil so that when it comes time for spring planting, the garden will be ready. With this plan in mind, the recent off-season activities for the Edible Demo Garden volunteers have concentrated on methods for giving the garden time to rest. The primary options for resting the garden are planting cover crops and allowing some beds to be fallow for a season.

 

Planting cover crops

There are many advantages to planting cover crops. Cover crops, sometimes referred to as “green manure”, are an excellent way to protect and improve soil. They increase organic matter, suppress weeds, prevent damage from wind and water erosion, and support beneficial insects and earthworms. Plus, they can look attractive while nurturing the garden.

Cover crops are divided into two main categories: legumes, such as clover and fava beans, and non-legumes, like rye and buckwheat. Legumes have the added benefit of fixing nitrogen by taking it from the air and converting it into a form to be used by plants. Cover crops are turned over when they start to flower and allowed to decompose prior to spring planting.

Two different cover crops were chosen for the Edible Demo Garden. Fava beans were planted in several of the garden beds and in the straw bales used for the summer crops. The latter is an experiment to determine if there is sufficient residual fertility in the straw bales to support another crop. In order to aid in germination and enhance their nitrogen fixing effects, the fava bean seeds were soaked in an inoculant containing rhizobacteria prior to planting. As an alternative cover crop, a green manure mix of bell beans, field peas, and purple/hairy vetch was planted in some of the raised beds. Past experience with crows eating the sprouting seeds necessitated the use of compost, straw, and protective netting to give the cover crop seedlings a fighting chance. The effectiveness of the different cover crops will be tested in spring when it is time to plant again.

 

Allowing beds to remain fallow

Taking a garden plot out of the crop rotation for a season can give the soil time to naturally replenish nutrients. It can also be a way to discourage pests, prompting them to move on once their food source is gone. However, fallow garden beds can also invite weeds and leave the soil exposed to the elements. In the Edible Demo Garden, layers of compost and straw were added to suppress weeds and protect the soil in the beds designated to be fallow. The winter rains will keep the soil moist and provide a habitat for earthworms and beneficial microbes.

Click here for more information on cover crops and soil enhancement in the off-season.

 

Herbs may not be the stars in the Edible Demonstration Garden, but they are notable members of the supporting cast. It’s hard to imagine a flourishing vegetable garden without a few culinary herbs as companions.

The supporting cast of herbs in the Edible Demo Garden includes basil, oregano, thyme, lemon verbena, chives, Mexican tarragon, anise hyssop, chocolate mint, lavender, pineapple sage, and rosemary. Some are harvested and sold fresh at the Indian Valley Organic Farm and Garden farm stand and others are dried and offered as seasonings and teas. They are among the most reliable plants in the garden.

What is an Herb?

The word “herb” can be applied to any non-woody plant with leaves, seeds, or flowers used for seasoning, medicine, or fragrance. It’s the culinary uses that most commonly interest home gardeners. Herbs are considered different from spices based on the part of the plant that is used. Spices are derived from the roots, bark, fruit, berries, and seeds of plants. Some plants can be both an herb and a spice. Coriandrum sativum, also known as Chinese parsley, is called cilantro when the green leaves are used as an herb and coriander when the seeds are used as a spice.

Why Grow Herbs?

Herbs are among the most satisfying plants to grow. Most are not fussy and can tolerate less than ideal garden environments. Many familiar herbs like sage, oregano, and rosemary are native to Mediterranean areas where the climate is similar to that in the Bay Area and therefore, they grow well in Marin gardens. There are many other good reasons for growing herbs.

• Herbs make good neighbors with other plants and can be easily integrated into both edible and landscape gardens. They are attractive enough to do double duty as ornamentals.
• Herbs are cost-effective. They are inexpensive to grow and can be harvested in the amounts required for a recipe. No need to spend money at the supermarket on packages of herbs.
• The blossoms on herbs attract pollinators and other beneficial insects.
• Herbs are usually not bothered by pests and diseases. Some herbs have been shown to repel pests affecting companion plants. An example is the ability of basil to deter thrips from invading tomato plants.
• Deer usually leave herbs alone, especially those with strong tastes and scents.
• Herbs grow well in containers and are a good choice when garden space is limited.

Tips on Growing Herbs

Most herbs thrive in full sun and well-drained soil, but many can be grown successfully in a range of conditions. Annual and biennial herbs such as basil, parsley, and cilantro have moisture and nutrient needs similar to those of other annual edibles and integrate well into vegetable gardens. Although perennial herbs like oregano, thyme, and sage require some regular watering, they are drought-tolerant and need little additional fertilization. They do well in more permanent locations or grouped together in an herb garden.

Some herbs are started from seed while others are easy to grow from cuttings. Information on the growing needs of common edible herbs can be found at http://marinmg.ucanr.edu/EDIBLES/EDIBLES_GROW_SHEETS/

Check the upcoming events listings on this website to register for a hands-on public workshop on growing and using popular edible herbs. There will be a workshop held on the College of Marin Indian Valley Campus on November 2, 2024, from 10:00 am to 12:00 pm.