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5050 SE Stark, 503-231-5050

9000 SE Division, 503-788-9000

Portland, OR

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Portland Nursery

August Gardening Tips

 

General Tips

Irrigation is the main activity that the gardener has to do frequently in August. The best way to water can vary greatly depending on the garden situation. Hanging baskets and full, healthy container plants can need a thorough watering every day, or occasionally more often. At the other end of the spectrum, established trees and large shrubs might not need any irrigation, or at most the occasional deep, thorough watering. Flower and vegetable beds and semi-established hardy plants fall somewhere in between. In such cases, always allow the soil surface to dry between waterings. Further, for plants with a root system that is at least somewhat developed allow the top layer of soil, say the top third to half of the estimated root system, to dry between waterings. You can test for moisture content in loose soils with your finger, or use a moisture meter in any soils. Be gentle when inserting the meter into packed or rocky soil as the tip can break off.

If your plants wilt, it is likely because the soil in the root zone is fully dry. Before you water, however, make sure the soil is indeed dry; sometime plants in quite wet soils can show symptoms similar to dehydration. This leads to overwatering and sometimes to root rot or plant failure.

Going on summer vacation? Hey, we can't blame you. That said, keeping the garden hydrated is always a priority to the gardener and you will need a plan. The best option is a friend, neighbor, or family member that can cover for you. While they may not know the nuances of your garden, they can probably figure out that the wilting annuals need a drink immediately. If that is not an option, consider getting yourself a timer and think through your irrigation system. A water timer can be attached to the hose spigot and set to turn the water on at certain intervals. Set the hose with sprinklers/drip system up so that it will cover the needs of your garden as best you can. We can help you get a tentative plan and provide the products needed to cover this.

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Perennials and Annuals

Most healthy annuals should be looking as good as they are going to get now. We usually have somewhat larger, developed annuals available in August in case you need that quick spruce up before a party or event. Dahlias especially are looking great about now. Continue to water and fertilize your garden as necessary. Pinch back petunias if they get leggy and regrow them. Many of the same issues that occur in July can continue throughout summer so please see our July tips page for information that is still relevant.

Heat loving perennials are at their best now. Most daisy-style flowers are available or are looking great in the garden. This includes asters, shasta daisies, and coneflowers. If you are adding new plants keep in mind that they will probably need small supplemental waterings in addition to what you are giving your garden beds in general. Continue to treat for hollyhock rust on your mallow family plants as necessary. Late August and into September is a great time to get a new groundcover started, whether in a recently cleared area or as a lawn replacement. As with any new planting, make sure it is kept moist until autumn rains set in.

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Vegetables

August means two things for vegetable gardeners; first, the beginning of harvest season for your summer crops! Early ripening tomatoes, eggplants, and peppers are starting to produce. The first of the garden beans are probably ready as well. There is an excellent guide to harvesting on our September tips page and I recommend you check it out for tips and details.

Second, August is a great time for starting fall batches of many cole crops and, in later August, greens and a new batch of peas. Cole crops include broccoli, cabbages, Brussels sprouts, etc. Short season root crops such as radishes and scallions can be started now, as well. Does it seem odd to be planting in the heat? Well, it will cool off soon enough so get those plants growing. As always, check our vegetable calendar for timing details. See all our culture information on our Vegetable Page.

Tomatoes giving you a headache? Well, some crops are more challenging than others. Tomatoes are subject to a number of problems as they develop. Consistent, moderate watering is probably the most important thing to preventing these from ruining your harvest. This means letting the soil partially but never completely dry between waterings. Other than that, watch for leaf spotting symptoms that can indicate late blight or other diseases. Once identified, these can usually be treated to still ensure harvest. Sometimes thinning the leaves and thickly grown plants can allow better sun penetration and air circulation, lessening disease pressure. Sometimes appropriate sprays can help; be sure to get a proper diagnosis first. Blossom end rot is when the bottom end of the tomato turns mushy and brown. This is caused by inconsistent soil moisture (yes, poor watering), wide temperature fluctuations, and/or a lack of calcium. The best way to ensure the presence of calcium is to add lime before you start your vegetables; yes, it is too late to do this now.

Your cucurbits (squash, cucumbers, etc.) are likely showing some powdery mildew by now. This is pretty normal. It is shown as a powdery white substance on the top of the leaf that rubs off to reveal some damage to the leaf. Ensure maximum sun and air circulation, and you can use fungicides to treat as you see fit.

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Trees, Shrubs and Fruit

Hopefully the fruit and flowering trees are recovering from any fungal problems they suffered from in the spring. Summer fertilizing can help to replace lost leaves; August is the last month it is generally recommended. Continued applications of fungicide are usually not needed as the fungi usually spread much slower in the dry summer air. Aphids can be a significant issue on larger trees, particularly maples and birches. Ever seen a tree 'dripping sap' in unreasonable amounts in summer? That is usually an aphid sign, not sap.

Sometimes it is appropriate to do some pruning of certain fruit trees in August, especially water sprout removal. These are the very vertical growths, frequent on apples, which shoot up after the fruit has started setting in spring. They are usually not desirable as future branches and can be removed. Major pruning can sometimes be done but is usually put off until winter. Note that some authorities recommend any major pruning or cherries and plums be done in summer, as some diseases can otherwise be an issue. Feel free to inquire about your tree's particular needs.

Roses and other repeat blooming shrubs can benefit from continued fertilizing if you have not done so recently. As most rose growers know, they usually benefit from continued use of fungicide to keep that black spot and mildew in check as well. Hey, nobody said they were the lowest maintenance shrubs (well, we didn't). Deadheading repeat bloomers sometimes makes for better or at least tidier reblooming. Examples of repeat bloomers include hebe, escallonia, cistus, and potentilla.

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Lawn Care

Most of us are familiar with the basics of summer lawn care; mowing, watering regularly, and fighting those dandelions. Here are a few tips that may help a bit. Do not mow your grass low to the ground. This can stunt the grass while allowing more light to the weeds in amongst your lawn. Mowing at four inches high is generally a good starting point. The old axiom on watering is one inch per week, watering only once per week. This works great for established lawns, but newly rooting seed or sod may need more frequent applications.

Many people have their sprinklers set to engage every day or every other day and this is unnecessary and sometimes even detrimental as the goal is to water deeply to encourage downward root growth. As for those dandelions, we sell tools specifically for pulling them out root and all (well, hopefully all the root). Also, regular applications of fertilizer and lime on a healthy lawn can help the lawn to simply outcompete some weeds. There are of course herbicides available for those who are not having success fighting weeds in other ways.

While there are many different pests and diseases that can affect lawns, there are no particular ones that are so common as to warrant attention here. If you see symptoms such as dead spots, unusual growth rings, or other strange symptoms feel free to check with us for a correct diagnosis and treatment.

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August Gardening

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