CONTINUE FERTILIZING CONTAINERS, FLOWERS AND VEGETABLES
Most of us fertilize our plants when we plant them. With short season vegetables that mature in 60 days or less, such as radish, spinach and leaf lettuce, that is probably adequate. Longer season vegetables and flowers need repeat fertilization. Containers need the most frequent fertilization because of lower soil volume and more rapid drainage and evaporation. One of the first signs that plants need additional fertilizer is when lower plant leaves turn yellow.
Osmocote and similar coated, slow release fertilizers are my favorite for containers. They are the longest lasting. General purpose fertilizers such as 16-16-16 work well for flowers and vegetables.
If you are irrigating your lawn, another application of lawn fertilizer will keep it green through the summer. I always recommend lawn fertilizers which contain part of the nitrogen in a coated or slow release form. Organic fertilizers are naturally long lasting.
ORGANIC PEST CONTROL
There is a virtual arsenal of natural and organic pesticides available now and more are being developed every year. A few have been available for 50 years or more.
One of my favorite natural pesticides is Neem oil, which is an extract from the Neem tree which grows in India. It repels most common insect pests such as aphids, mites, thrips, cabbage worm, caterpillars, mealybugs, beetles and leafminers. Neem oil is also a very good fungicide for leaf disease control. Since Neem oil is harmless to humans and pets, it is also safe to use on vegetables.
Rotenone and Methoxychlor are two older insecticides which are natural plant derivatives. They are found in many different brands of natural insecticides.
Diatomaceous earth consists of fossilized remains of diatoms, a type of hard-shelled algae. The fine powder absorbs lipids from the waxy outer layer of insects’ exoskeletons, causing them to dehydrate. It is very effective on maggots in root and cabbage family crops if applied in the soil on top of seed or on the roots of transplanted plants. It has been available for at least 150 years.
Spinosad is a natural pesticide available for only the last few years. Spinosad is a compound found in a bacterial species: Saccharopolyspora spinosa. It kills insects by disrupting their nervous system. It is widely available in a number of formulations. One formulation called Sluggo is effective on slugs, snails, earwigs, cutworms, sowbugs and pillbugs.
Insect predators (parasitoids) such as lady bugs and lace wings can be purchased and released. Newer parasitoids include wasps, mites and midges.
Insecticidal soap has been widely used for years to wash pests such as aphids and mites off of plant leaves. Once on the ground they cannot find their way back onto plants.
Various plant oils such as citrus, pepper, jojoba, canola, soybean and mustard are used to repel insects. Several brands of these “organic insect controls” are available and effective in preventing damage.
Highly refined petroleum oils are used to smother insects by clogging their breathing pores. These horticultural oils have been widely used as dormant season sprays to kill overwintering insect pupae and eggs. They can also be used during the growing season when temperatures are below 80 degrees.
Bacillus thuringensis, sold as Dipel and Thuricide, has been used for years to infect various caterpillars (worms) with a bacterial disease.
“Cease” is a contact biological fungicide that contains a strain of the bacterium Bacillus subtilis. It controls common fungal diseases such as Botrytis, Powdery Mildew, Anthracnose and several leaf spot diseases. It also controls bacterial diseases as well as soil diseases.
ORGANIC WEED KILLERS
Unfortunately, the selection of organic weed control products is much more limited than organic pest and disease control products. There are just 2 types of products available: non-selective sprays which burn or desiccate weeds, and granular weed preventers which prevent new weeds from germinating and growing.
A number of natural plant oils are effective in removing the waxy cuticle of plant leaves which causes them to dry out and die within a day or two. Citrus, lemongrass, soybean and a number of others are used in a wide range of organic weed control brands. One brand uses potassium salts of fatty acids. They are available in ready-to-use sprays and in concentrates.
These products are faster acting and just as effective as Roundup and other non-selective chemical weed killers on young actively growing weeds. Older weeds and perennial weeds will need more than one application. These natural weed killer sprays work best if applied during warm, dry weather. They are non-selective and should not be sprayed on desirable plants.
The granular weed prevention products contain corn gluten. Corn gluten prevents germination of seeds with which it comes in contact. Weed control is effective for about 4 to 6 weeks. Some of the corn gluten products also contain organic fertilizer which stimulates the growth of nearby desirable plants. Corn gluten can be applied to lawns as well as flower, vegetable and shrub beds. To be effective in preventing lawn weeds, corn gluten should be applied in March. It can be applied to vegetable, flower and shrub beds any time of the year. The best time to apply is right after existing weeds have been removed or killed or new plants have been planted.
The best way to minimize weeds in lawns is to maintain a healthy, thick turf. Most weed seeds require light to germinate. A thick turf does not leave light or room for weeds. Management practices which produce a strong, weed resistant lawn include regular fertilization at least twice a year, a high weekly mowing height (at least 2 inches) and a consistent, spaced irrigation schedule. Lawns should be irrigated on a three day or longer schedule. Daily watering keeps the top of the soil moist which is ideal for germinating weed seeds.
MAKE SECOND PLANTING OF SHORT SEASON VEGETABLES
You are probably picking short season vegetables such as radish, lettuce and spinach right now. Now is the time to make a second planting for harvest later this summer. I like to make a second planting of bush green beans about a month to 6 weeks after the first planting. This is an ideal time to plant root crops such as carrot, parsnip, turnip and rutabaga that benefit from cool weather to improve their flavor. We have a growing season which extends well into October. There is still time to mature almost any vegetable including tomatoes, corn, melons and winter squash.