Tidewater Gardening - July 2011


Its Not Too Late to Vegetate!
K. Marc Teffeau


While many people take their vacations during this month, there is still plenty to do in the garden and landscape. Planning and planting the fall garden should be done now. Most folks consider vegetable gardening a spring and summer activity. With a little bit of attention and care, an excellent fall garden is possible in this area. In fact, many of our cool season crops such as broccoli, cauliflower and cabbage do better as a fall rather than as a spring crop on the Eastern Shore.
Start your broccoli, cabbage, and cauliflower seeds now so you can set them out as fall transplants in August. It is difficult to locate fall vegetable transplants in this area as most greenhouse growers are oriented to the spring season. Mid to late July is a good time to direct seed lettuce, spinach, beets, carrots and turnips into the garden.
They may be a little slow in germinating because of the high temperatures. Try lowering the soil temperatures by covering the seed bed with a floating row cover like “re-may” or some other shading material. Succession plantings of green beans can go in until the first of August. Wait until August for the fall planting of peas.
In addition to planting the fall garden, be sure to keep the diseases and insects under control. If you have tomatoes or eggplants, I am sure that the Colorado Potato Beetle has found them. These insects are very difficult to control in the home garden. I would suggest that you start with either hand-picking or using a botanical insecticide. If all else fails, two bricks are very effective. The leaf containing the pest is placed between the two bricks and sufficient pressure is brought to bear to render it into a semi-liquid state.
If you do apply an insecticide or fungicide to your vegetable garden, apply in the early morning. Application in the high heat and sun during the middle of the day can actually result in the burning of the plant’s foliage by some of the pesticide formulations. The insecticide Sevin® is well known to burn foliage if applied at air temperatures above 85º.
Watering is a particularly important activity now to offset the effects of mid-summer heat. By now the root systems of the annuals and perennials have completely developed and require lots of water. We usually have dry period in mid-summer, broken only by an occasionally late afternoon thunderstorm. If you happen to be in the area of the storm, you might get a nice shower while the rest of us stay hot and dry.
It is important to water correctly. What seems to be a simple task is really quite important. The best watering method is also the easiest: an occasional but generous soaking in the early morning. If possible, run the hose into the garden or flower bed and leave it in a spot where a slow, constant flow will do a thorough job of watering. The soaker hoses made out of recycled car tires are excellent for this purpose.
When you water in the mid-day heat you run the risk of scorching plant leaves. Plus you loose upwards of 50 percent or more of the water to evaporation. The objective of watering is to provide moisture to the root system rather than soak the foliage. Watering in the evening should also be avoided as this encourages the development and spread of foliar diseases. The gardener who goes out after dinner and spends 15 minutes spraying the lawn and the flowers is wasting time, water and causing disease problems.
I would also encourage gardeners, if they have the space, to hook up a rain barrel or two to their downspouts. There are many different styles and sizes available to choose. A simple device that I bought last year from the Gardener’s Supply Company allowed me to directly hook my rain barrel into the downspout.
A major soil borne disease that starts to show up in the landscape in July is Phytophthora. As the soil warms up, this disease becomes apparent in many azalea and rhododendron plantings. Sections of the plant and in many cases the plant itself just up and dies in a matter of weeks. Many gardeners move here from the western shore and find that they just can’t grow these plants like they did in their former location. The Phytophthora disease organism thrives and spreads in soils that are warm, wet and have a pH range of between 4.5 and 6.
You can prevent the spread of this disease and protect you azaleas and rhododendrons by following a few recommended and approved cultural practices.
First, always plant these plants in a well-drained soil where water never collects. For many people this may mean planting in raised beds to get the proper drainage.
Second, plant your plants on the north, east, or northeast sides of your home or landscape so that they will be shaded and the soil will remain cool. A common planting mistake I continue to see is where people make a foundation planting of rhododendrons on the southwest side of house, in direct sunlight and right next to a black-topped driveway. The heat buildup in this site kills the plants in less than a year.
Third, keep the soil around the plants cool with a two inch mulch of pine bark or pine needles.
Fourth, avoid using peat moss either as mulch or in the soil around the plants. Peat moss holds too much water and can contain the Phytophthora disease spores.
Last, test the soil and try to maintain a pH of 4.5.
Poorly drained soils, in addition to encouraging Phytophthora, can also result in the death of many woody ornamentals just from drowning of the roots. This is especially true in areas where the soil drainage is borderline; not too good but not that bad.
Under normal conditions, ornamental plants have been able to survive without difficulty. Excessive amounts of rainfall that occur on occasion will result in a number of ornamentals dying. Root damage caused by the exclusion of oxygen to the roots usually does not become apparent until long after the rain subsides. Damaged roots will fail to keep the plant alive during the heat and drought stress during July and August.
Symptoms of drowning roots are yellowing, browning and premature leaf fall of trees and shrubs. Some plants even show fall coloration which generally does not occur until mid-fall. The plants will often lose all their leaves. The best solution to this problem is to not plant in poorly drained areas. Sometimes you can improve the soil drainage with raised beds and drainage tiles, but this can become an expensive cure.
July is the time when your bearded iris should be divided and replanted. Dig them up carefully and throw out – do not add to the compost pile – the diseased and borer infested rhizomes. Separate the rhizomes and dust the cut ends with sulfur to reduce potential rot problems. Plant the iris with the top of the rhizome barely showing above the ground.
Direct summer sunlight can be a problem for the roots of many perennial plants and bulbs, particularly lilies. Lilies do marvelously in sunny spots, so long as their roots are shaded. For this reason, many gardeners plant lilies amid a perennial ground cover or in the perennial border. If your lily roots aren’t in shade, now would be a good time to add a two inch layer of mulch to moderate the soil temperature.
July is the time when many retail garden outlets use a mid-summer clearance sale to rid their sales yards of plants left over from the spring sale season. In properly managed sales yards, where plants have been watered and fertilized and where insects and diseases have been controlled, the plants are still in good condition. Balled and burlaped or container-grown shrubs and trees will tolerate transplanting now if you give them some extra attention including proper watering. Do not attempt to transplant bare-root plant material now.
Be careful about buying clearance plants where the sale of plants is a side income source or just one of the many seasonal retail items that the store carries. In these situations, little attention has been paid to the proper care of this material while on the lot. When selecting sale plants under these conditions, make certain that the plants are alive. Regardless of what the sales clerk tells you, horticultural scientists have not yet discovered a method of reviving dead plants.
Happy Gardening!