Last Class for Container Gardening

Your final project is due tonight for all credit students  

Here are some of the lecture notes:  

Maintenance: what is necessary to keep containers healthy?

“Clean the terra cotta pots each year to prevent passing along fungi, bacteria or viruses. Remove plants and soil from the pots and bake the containers in the oven set at 220 degrees Fahrenheit for an hour or so to kill anything residing on the pots. Allow them to cool slowly to room temperature before moving them. Another option for cleaning terra cotta pots is to soak them in white vinegar Rinse well and let the clay pots sit for a couple of days to dry out before replanting.” I would try the vinegar solution, but baking my containers? NONSENSE!!

Watering and Fertilizing Plants in Pots

Fertilizers are salts – if you overfertilize, salt build up – my regimen, low fertilizer will prevent this from happening most of the time unless there is excess salt in the clay itself...

Plants in containers need frequent watering compared to in-ground gardens due to limited soil volume and because exposed sides lead to greater evaporation.

Water when the top 1 or 2 inches of potting soil feel dry, saturating the potting soil.

If there is some doubt that soil is thoroughly moist -- if plants wilt quickly or if potting soil pulls away from the container's sides -- occasionally soak pots in a sink or bathtub of tepid water to make sure the potting soil is fully saturated. Never soak plants for more than a few hours; also drain excess water from drain trays to avoid drowning plants by driving out all soil oxygen.

Soluble Salt Buildup in Clay Pots

Plants dry out sooner in clay pots than plastic containers, but the permeability of clay pots can be helpful -- especially when removing soluble salts, which can build up in soil to toxic levels. When clay pots "wick away" moisture from the soil they contain, they also absorb soluble salts. These salts sometimes come from water high in carbonates, salts or other minerals. They also come from inorganic fertilizers -- which potted plants generally need, because they are not grown in true soil -- and sometimes also from potting soil mixes derived from animal manure.

Preventing Salt Buildup

1. Use quality clay containers that will not have a high salt content to begin with.

2. Control the amount of fertilizer you apply – especially of inorganic fertlizers (the blue crap for example).

3. Water as I showed you – water when you water and see that water is flushed through the entire container

Following this regimen will prevent most of the salt buildup that folks experience.

Removing Salt Buildup on Clay Pots

Soak salt-stained terra cotta pots -- without potting soil or plants -- for a few hours in vinegar to remove salt deposits. If pots are heavily salt crusted, soak them for 10 or 12 hours then scrub thoroughly with a steel wool cleaning pad or a wire brush.

Most advice on sterilizing your containers is from people with far too much time on their hands – most of the sterlization at the Learning Garden is done with sunlight and air. Containers are usually allowed to breath between plantings – if they are really dirty, we scrub them out, and are left to dry. In 15 years, we've had no soil born insects or pathengens pass from plant to plant in our containers.

Uusally a 10% bleach solution is recommended. If you have clothes you want to ruin, go for it.

We've done renovation.... Questions?

Use a machete to remove plants from a straight sided container – curved containers are more difficult, if you can find an old saw blade and use it, you might find it works.

Pests

Less fertilizer will net you fewer insects – high Nitrogen causes a sweet succulent growth that attracts pests like the Vegas Strip attracts pests of a different sort.

Adapt a policy of 'Acceptable Damage” - how much damage will you allow on a given plant – it will vary from species to species.

Do not plant plants that will have an unacceptable level of pest infestation for you, i.e. eugenia

Do not plants plants in areas they will not fare well. Plants placed in conditions that don't favor them will also attract pests.

ANY spray, chemical and especially organic ones, KILL more than your target species. Consider the plight of the honey bee and think HARD before you spray.

If you must spray, I ask you use organic pesticides and spray ONLY at dusk. Honey bees will have returned to the hive and the pesticide will be dry by morning and so will not harm them. Still, your spraying will kill unintended victims – most infestations are spotted by beneficial insects before humans and the eggs of beneficial insects will be among your victims.

Some of the common LA pests

• aphids – sucking insects in white, black, green and pink. If the infestation is within parameters, consider first off of leaving it be, if too much for you, then either wash off with water, rub off with a gloved hand – spraying with an insecticide – even an organic one, should be the course of last resort
• cabbage looper – white moth lays eggs hatching out a voracious little green larvae that can devour an entire plant in a few days – hand picking works. Bt is somewhat innocuous. Attacts mostly cabbage family members, but is similar enough to the hornworms that attact tomatoes and other members of that family – even though it's a different species they are for practical reasons treated about the same.
• Powdery mildew – we've discussed controls in class
• Slugs and snails – beer traps, hand picking and physical control
• Find more data here: http://www.ipm.ucdavis.edu/PMG/menu.invertebrate.html

Year 'round Interest

A general, non-specific discussion about how to keep your containers interesting through out the year.

Thank you for your participation in this class - you are what makes this work or not - your enthusiasm is contagious and I know you'll have many wonderful containers planted in the years to come! 

Good luck!  

david