Watering Gardens in the Heat

Here’s the deal on watering in the heat. So there’s been a heat wave and some inexperienced gardeners see their garden plants wilting and assume it’s a lack of water.

Before you water a wilting plant – put your finger on the soil to see if that soil is damp a few centimeters below the surface!

Plants wilt because they’re losing more moisture than they can pick up from their roots.

If there is adequate soil moisture, adding more isn’t going to make it any easier for the plant to survive, in fact it is only going to make the plant’s job harder. It’s called soil water saturation and this leads to root rot. And more wilting.

If there is adequate soil moisture, the appropriate action is to take a deep breath and allow the plant to recover on its own in the evening. A thick layer of mulch will help the soil temperature stay cool during heat spells and this in turn will keep the plant healthier

This is particularly true of container plants. Always finger-test the soil here before you water, particularly if you see wilting and during periods of high heat.

Overwatering creates root rots and wilting isn’t always a sign of a lack of water in the soil

Why You Can’t Grow Calibrachoa and Other Plants in Containers

Many gardeners have trouble growing plants such as Calibrachoa and don’t know why they can’t grow them in containers. Here’s the deal to understand.

This plant is often described as a “high feed” or “high iron” plant and while they do love to be fed, and won’t produce well under low-feeding regimes, there are other factors at work.

Plants such as Calibrachoa lack the ability to take up iron under high-intensity cultivation – and this is particularly true when the soil media pH is too high.

In order to succeed then, you have to ensure the soil acidity stays acidic.

In order to succeed then, you have to ensure the soil acidity stays acidic. If you have high-alkaline water, you’re turning your soils alkaline with every watering. And thus making it hard for this particular plant to thrive.

In our greenhouses with our high-alkalinity, high-pH water, I had to add acid to the water in the propagation house to make sure I didn’t wreck the pH of the soil with these tender seedlings and cuttings. Once out in the nursery and garden, they were fine (for the most part).

Understand that plants in containers thrive on soils that are more acidic

Also, understand that plants in containers thrive on soils that are more acidic than the preferred soils in-ground culture. In other words, grow a bedding plant in a container and it wants more acidic soil than it does in the garden.

Iron deficiency symptoms

Iron deficiency symptoms include chlorosis (yellowing) of the younger leaves and mostly concentrated along the stem and lower section of the leaf next to the stem.

There is usually minor “netting” of the remaining green leaf surface. Note that once these start to happen (in even a barely noticeable way) the plant becomes susceptible to other issues such as moderate overwatering or root disease.

In other words, the iron deficiency reduces its ability to fight off minor stress.

The best pH is between 5.5 to 6.2 for Calibrachoa. On the whole, keeping pH around the 6.0 mark is the best plan.

If you see growing problems with this plant, then do check for soil pH first and if that’s fine, investigate further.

A regular soil test kit will give you “close-enough” data.

If pH is too high

If the soil pH is too high, then you have to acidify the soil and you can do this by adding acid to the irrigation water (vinegar works well on the home scale and you do have to test to bootstrap your way to a 5.5-6.0 water pH test ) or using an high-ammonium, acid-reaction fertilizer (such as 21-7-7 or 9-45-15) will drive the pH down. Adding an iron-drench to supersaturate the container soil is sometimes used as well.

Cool, humid and low-light conditions can make a small problem seem much worse.

So if you’re having problems growing this particular plant, or even trouble growing a great container plant, now you know how to go about it and produce a show garden.

Here are other container gardening ideas you’ll want to know

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