Herself’s Houston Garden

I know you’ve all heard of pH and those of you with pools are probably very familiar with pH. But why do you care about your garden soil pH?

The ‘p’ in pH stands for ‘potenz’ ( potential to be ) and the ‘H’ is for ‘Hydrogen’. So pH is just a measure of the amount of hydrogen in your soil. The scale runs from 0 to 14 ( acidic to alkaline ) and you are aiming for 6-7 but your plants will be thrilled with anything between 6-8.

I have no idea what my soil pH is, I’m waiting for my soil test to come back. However I’m told the Houston area has acidic soil, most everything north and west of us has alkaline soil.

The pH is important to plants because plant nutrients are not soluble when the pH is too high or too low. 98% of the nutrients your plant needs it gets when the roots take in water. If the pH is too high or too low the nutrients in the soil do not dissolve and your plants can’t use them.

Think about being stuck on a plane. You have a bag of cookies in a sealed plastic bag and nothing sharp to slice the bag open. You have the food but no way to eat it. This is what happens to your plants when your soil’s pH is too far from center.

If your soil tests below 6.0 you’ll want to add limestone to your garden. The amount you add depends on how acidic your soil is. Limestone takes a very long time to work its way down into the soil so it may take a while to see your results.

If your soil is about 8.0 you’ll need to add sulfur to it to lower the pH. This also is a very slow process. If you add to much sulfur too quickly you’ll wipe out your plants.

pH should be checked yearly. ( Yes, I know, I’ve been gardening forever and this is my first year testing but better later then never. It just shows you can teach an old gardener new tricks. ) You can send a sample to the county for testing. Many garden supply places carry soil pH kits.

Nitrogen, Phosphorus and Potassium are the three primary nutrients in any fertilizer. The three numbers on your fertilizer container represent Nitrogen (N), Phosphorus (P) and Potassium (K) in that order. The number is the % by weight of the nutrient contained.

Nitrogen is the primary building block for plant protoplasm. Protoplasm is the translucent substance that is the living matter in cells. It is needed for flower differentiation, speedy shoot growth, the health of flower buds and the quality of fruit set. It also acts as a catalyst for the other minerals.

If you have too little nitrogen leaves become yellow-green, the oldest showing yellowing first. You will see the tips of leaves turn brown and the brown will be surrounded by yellow than green. The brown and yellow strips are V-Shaped. Since the plant can move nitrogen, when it is low it takes it from older growth and gives it to newer growth. Growth is reduced, there will be less and small fruits.

If the nitrogen is too high then fruits take longer to ripen, will be soft and have short storage life. Too much nitrogen also hurts root growth and water efficiency of plants. It also will make your plants less tolerant of our cold spells.

When buying nitrogen for your plants spend the money for the slow release formula. Soluble can cause leaf burn and rapid growth for a week then nothing. Soluble must be reapplied frequently and in the end costs more because you need to apply it more often. Except of course in your vegetable bed where you want rapid growth for the short growth season.

Phosphorus is needed for energy transfer and storage in plants. It is needed for the formation of nucleic acids ( RNA and DNA ). It helps plants to mature and promotes root, flower and seed development.

Phosphorus is also mobile in the plant showing in older leaves first. Too little phosphorus causes leaf die back, older leaves stems and veins may appear purple. The plant will be slow reaching maturity with poor seed and fruit quality.

Potassium is needed to activate enzymes, form sugars and oils. It improves cold weather tolerance. Fruits will be a better quality with better color, less acidity and more oil and thicker skins.

Potassium is also mobile, too little potassium causes leaves to curl and distort, oldest leaves first. Older leaves may get brown edges and tips and drop. Stalks may be weak or short. Root systems will not develop properly.

If potassium is too high then there might not be enough nitrogen to keep up and a nitrogen deficiency can develop.

It is important to keep nitrogen and potassium in balance. Higher nitrogen and less potassium is good for leaf growth, your lawn and other foliage plants prefer this. High potassium lower nitrogen is better for flower, fruit and vegetable growth.

More information:
Progressive gardens has photos of several deficiencies in plants

I’m reading a flyer on cold weather and plants put out by the Tarrant County Horticultural Office and the first advice is if it can’t handle the cold don’t plant it. Clearly this was not written by a gardener.

Skipping that sage advice and moving on to more useful notes we have: Plant tender plants in warm, protected locations. ( I guess design is not a consideration either. )

The most protected areas for tender plants are:

Close to your home, underneath overhanging eaves.

The best location is under an eave on a south facing side of your home. The house will soak up sunlight all day and radiate it out in the evening.

The least protected areas for tender plants are:

Open areas that are exposed all around particularly on the north side. The north winds are a main cause of damage.

Shallow areas that are enclosed. Colder air will drop and it will settle into low protected spots in your garden.

And…

1 ) Fertilize in October to give your plants the nutrients they need for the winter, then not again until late March. Do not fertilize them in the winter. Plants in an active state of growth and newer leaves and stems are most likely to be damaged by the cold.

2) Reduce but do not stop watering your plants. Plants stressed by a lack of water will incur more harm.

3) Wait until spring to prune the damage! If you prune too soon, you will get new growth which will be killed by the next frost. And plants that seem damaged beyond hope often are not. Be patient.

4 ) Mulch heavily around tender plants in the fall. Leaves, newspapers, bark, straw all work well. Mulch high around tender plants. Some people use the pipe insulation tubes you can buy at the hardware store to protect tree trunks and other tall thin plants.

See also:
What to do about frost damage
Protecting your plants from cold weather
Lack of water does more harm than the cold in winter months

Epsom salt provides much needed magnesium and sulfates to your plants. It does not build up in your garden the way fertilizer salts do. Magnesium sulfate is needed for seeds to germinate, and magnesium is critical to the formation of chlorophyll. Your plants need chlorophyll so they can turn the sunlight they receive into food.

A common sign of a lack of chlorophyll is yellowing leaves whose veins remain green.

Tomatoes and roses want 1 tablespoon of Epsom salts per gallon of water/ 2x month.

Shrubs want about 1 tablespoon spread over a 3′x3′ area. So about 1 tablespoon per bush if you don’t have them too close together.

Trees use about 2 tablespoons per tree or 2 tablespoons per 3′x3′ area.

Over the beds use 1 cup per 100 square feet, about 1 cup for a 10′x10′ bed.

The sulfur compounds in Epsom salts also make it easier for your plants to absorb the fertilizers you use.

You can find small containers of Epsom salts in your local pharmacy. Big bags can be found with the lawn fertilizers at the local HD/Lowes/Walmart type stores.