September

Cooling, shorter days
Succulent harvest abounds
Prepare now for cold

Fresh figs! (Kate Russell)

Harvesting the fruits of all that labor and preparing for winter keep the September gardener busy. Deadheading, clearing away debris, and composting spent annuals all help to prevent future problems with pests and diseases.
​
​
Apples
​
Many apple varieties are ready for harvest (assuming the birds have left any uneaten). Other apple varieties will need some colder weather to sweeten. If you notice small brown, corky areas under the skin, it is called bitter pit. Bitter pit, like blossom end rot in tomatoes, is caused by a calcium deficiency early in the spring. In this case, however, the condition can be treated on future crops by spraying the leaves with calcium nitrate just after bloom and again one or two months later. Use one tablespoon per gallon of water.


Carrots

Carrots prefer loose soil, but shorter varieties perform well enough in our heavy clay. The addition of compost can help aerate the soil and provide valuable nutrients. Carrots should be planted no more than 1/2” deep and plants should be thinned to 3” apart, to avoid forking and twisting. Water regularly but allow some drying to prevent cracking. Successive plantings provides an ongoing harvest. Carrots can be planted between landscape perennials for productive use of space.


Cover crops

Areas of the garden that would otherwise be left bare over the winter are better off mulched or planted with cover crops. Cover crops help maintain important soil microorganisms that will, in turn, support your spring and summer crops next year. Fava beans are an excellent choice in San Jose, California.


Leafcutter bees

If rose leaves are exhibiting neat round or oval holes in them, it is probably the beneficial leaf cutter bee and should be ignored. The sections of leaf are used to line brood cells, which are also filled with nectar and pollen.
​

Mosaic virus

Squash and cucumber plants are susceptible to a disease carried by aphids and cucumber beetles. Mosaic virus causes leaves to become mottled and stunts plant growth. Fruit may become white. Diseased plants should be removed and put in the trash. Do not add to the compost pile.


Pests

If leaf stippling and tiny webs are seen, spider mites are probably the reason. Spider mites prefer dusty conditions, so spraying infested plants with the hose can help. Using broad spectrum pesticides is not recommended because they will kill the spider mites’ natural predators. Heavy spider mite infestations can be treated with insecticidal soap or horticultural oil. Stink bugs and cucumber beetles are common in San Jose this time of year.


Powdery mildew

As nights become cooler, it is common for powdery mildew to strike. Affected leaves should be removed and thrown in the trash, and overhead watering should be avoided.


Rats

Gnawed tomatoes, empty orange shells, and tiny black pellets are all signs of roof rats. These pests can infiltrate your attic, crawl space, garage, storage shed, and trees. Rat traps are an excellent way to remove resident rats. Keeping pet and livestock food sealed up and harvesting crops as soon as possible will help make your yard less desirable to the local rat population. Since rats can carry serious diseases and damage electrical wiring, it is worth the effort to get rid of rats. I use traps placed in a tunnel made with cinder blocks and  baited with peanut butter or cheese.


Tomatoes

Any yellow flowers produced by your tomatoes now will not have time to mature before temperatures cause fruit to turn mealy before maturing. Instead, remove those flowers to encourage plants to put all their energy into any fruit that is already on the vine.


Vegetables

September is the time to plant many winter crops, including artichoke, arugula, beets, bok choy, cabbage, carrots, cauliflower, chard, cilantro, collards, dill, fennel, kale, kohlrabi, leeks, lettuce, parsnips, peas, radishes, rutabagas, spinach, and turnips.


Enjoy the fruits of your labor!