pH

July 2017

Pickaway to Garden

 

pH

 

By Paul Hang

 

Although PH are my initials, this isn’t about me. If you push the PH button in an elevator you’ll end up in the Penthouse, but not in Trump Tower. P. H. can be an abbreviation for Purple Heart or Public Health. Ph in chemistry is a symbol for the phenyl group. pH, our topic, stands for potential of Hydrogen.” It is the measure of the acidity or alkalinity of a solution, such as vinegar or a damp substance such as soil. The pH of pure water is 7 with lower numbers indicating acidity and higher numbers indicating alkalinity.” ( Encarta Dictionary)

 

The pH of soil is perhaps the most important and first consideration when attempting to grow any plant. Soil pH affects soil microbial activity, some soil chemical reactions and nutrient availability. Gardeners need to be aware of the effect that pH has on the availability of nutrients. When we notice that a plant is not doing well a lot of us reach for the bag of fertilizer. And, if a little will help, then a lot will do even better. This tendency can be a waste of money and can do more harm to our plants and our environment. Just ask the people of Toledo how fertilizer runoff can affect you.

 

Without getting overly technical, pH is the measure of the hydrogen (H+) ion concentration in solution. The higher the concentration, the lower pH becomes. pH is measured on a scale of 1-14, 7.0 being neutral. Lower than 7.0 being more acidic (lemons 2.3) and higher being more alkaline (ammonia 10.6-11.6). Increments between each number represent a ten-fold increase.  For example, at pH 5 it is ten times more acidic than at pH 6. The pH of your soil affects the growth and health of your plants. As an example, low soil pH can decrease phosphorus availability and inhibit root growth. Low soil pH also limits the release of some nutrients from soil organic matter and reduces nitrogen fixation by legumes (clover and beans). Soil pH does not have to be neutral (7.0) for maximum nutrient uptake. Corn can be productive in soils with pH levels as low as 6.0.

 

The point to be remembered is this: Even if the required nutrients are in your soil they may not be available if the pH of your soil is not right for the plants you want to grow. Some broadleaf evergreens (azalea, rhododendron. holly, blueberry, prosper in acidic soils. To lower pH to make the soil more acidic add sulfur. Overly alkaline soil   interferes with plant uptake of iron and leads to yellowing of leaves or chlorosis. Plants affected by chlorosis include evergreen shrubs, raspberries, roses, mountain ash, pin oak and currants. Iron sulfate reduces alkalinity and adds iron.

 

Most soils have a pH correct for most plants. It is the extremes that interfere with nutrient uptake. Soil pH of 6.0-7.0 is suitable for most plant growth, the examples above being the exceptions. Gardeners should know the pH of their soils. “Don’t guess, soil test.” Go to www.css.wsu.edu and search “pH nutrient availability” for a chart that shows the availability of certain nutrients by pH level. From now on, if someone says they have a pH problem don’t look at me.

 

Check ohio-line.osu.edu for bulletin HYG-1132 for soil testing and other bulletins for problems you notice in the garden. Need gardening advice? Call the Gardening Helpline 474-7534. To read a weekly discussion of problems facing those of us who “grow things,” check out bygl.osu.edu. Buckeye Yard and Garden Line (bygl) is a real education. Experts discuss what to do. It is updated weekly.

 

Things to do in the garden:

 

This is the time to dry herbs. The best flavor is had by harvesting just before they flower. Pick on a sunny dry day and in the morning. Tie them in small bundles with rubber bands. Hang them upside down in a hot, dry, dark, well ventilated spot in an attic, barn or shed. This is also the time to harvest garlic and hang them or lay them out to dry and cure. Harvest when leaves are turning yellow but there are still one or two green leaves.

 

The gardening season is in full swing. Weeding, deadheading and watering are high on the list of routine activities. If July turns out to be bone dry as usual, water the equivalent of one inch per week. Mulch to conserve moisture and keep down weeds. If you haven’t mulched yet do so after a soaking thunderstorm or a good watering. Vegetables higher in water content need more water e.g. watermelons, onions vs. green beans.

 

Keep your mower blades sharp; cut your grass long, 3 inches is ideal. If you use a pesticide for grubs you are also killing the ones that produce fireflies. Consider organic methods if you have a grub problem.  Kill Japanese beetle scouts before they let their comrades know about your garden. Brush them off into a cup of soapy water or alcohol (not Jim Beam). Repeatedly letting the lawn go dormant and reviving it by watering can kill the grass. Either keep watering or wait for Mother Nature to do it for you. Don’t forget to water your compost heap. It needs to remain moist for fast decomposition.

 

Going on vacation? Water well before you leave. Place container plants in a shady area. They should do fine for a week depending on the weather. If you will be gone longer have someone reliable come over and water regularly. Container plants in the hot sun may need watering daily.

 

If your grafted trees or roses are sprouting below the graft, cut the sprouts off.

Keep picking seed pods off the annuals and clipping spent flowers (deadheading) to encourage bloom all summer. Pinch back mums July 15^th for the last time.

 

Always read the labels on your plants for fertilization, however most woody plants have pretty much completed their growth and their buds for next year. So fertilizing trees and shrubs after early July is a waste of money and may harm the plant. Keep watering trees and shrubs planted in the past 2-3 years.

 

Consider planting a fall garden this month. Cool weather vegetables can be planted  this month to take advantage of the coming cool fall weather. Plants such as cabbage, broccoli, spinach, collards, cauliflower, Brussel sprouts (plant seeds now, seedlings by mid-month), kale, Swiss chard even beets and parsnips thrive in our fall weather. If it is hot and dry, consider starting your plants indoors (except for root crops). Acclimate them to the sun before putting them out in the garden.

 

Other vegetables that grow well in cool weather but should be planted a little later because they mature quickly and don’t do well in heat are: lettuce planted through August and September, carrots and radishes in September.  With a cover, when frost threatens, I have harvested fresh salad greens for Thanksgiving dinner. There are about 110 days before the average frost, veggies that have that many days to harvest can still be planted. Check the seed packet. There are also some other varieties of vegetables that can overwinter for harvesting in the spring.  Check varieties in seed catalogs or on-line. Order now.