Scorching forecast:

• There is a heat wave forecasted for next week.
• Therefore, I wanted to provide some tips and insight on how to successfully prepare your garden for a heat wave.

 

The hot problem for any plant:

• Unseasonably hot weather may catch your plants off guard.
• If they are not adequately acclimated, the extreme high temps can cause all kinds of bad things such as leaf scorch, leaf droop, fruit drop, stunting and even plant death.
• Yes, even hearty succulents and cactus can be damaged by extreme hot weather if they are not ready for it.

 

Plants most at risk:

• The newly planted and young are the most vulnerable to heat stress.  Part of this has to do with the fact that these plants don’t have the matured root system needed to keep up with extreme water evaporation from the leaves.
• In addition, plants of any age that are infested with parasites such as aphids are at additional risk.  This is because the parasites are also literally sapping additional fluids out of the plant.  Furthermore, these parasites will be sucking even more than usual during the hot days because those bugs will also be trying to hydrate themselves in the hot weather.

 

 

What to do?

• There are three major things that you can do to decrease the negative impact of a heat wave… and even come out ahead.
• Below is my heat wave checklist.

 

1. Over water your plants.

• When the forecast warns of a heat wave, I increase the settings on my automatic irrigation system.  However, for the plants at additional risk, such as the newly planted, I will also go out with a garden hose and give them an extra soak.

• The most efficient time of day to water your plants is in the very early morning.  This will allow the water to soak down deep without excessive loss of water through surface evaporation. You could also water in the early evening.  However, the drawback of that nighttime approach is that prolonged nocturnal moisture can promote fungal growth.

• Regardless of when you water, a key factor is to plan ahead of the heat.  Meaning… you should water your plants before you see signs of heat/water stress such as wilting leaves.  Another words, if you water on the wrong side of the equation, it may be too late for the health of your plant.  There is a tipping point for a water stressed plant, and if that point is passed, an unavoidable cascade of negative events will follow.

• On the up side, high temps can also stimulate growth.  Therefore, if you can successfully keep up with the water demands of your plants during a heat wave, your plants may reward you with a new flush.  I have found this to be particularly true with citrus.

 

2. Shade the young ones:

• The combination of extreme dehydrating heat and sun can burn leaves and branches. These effects can be curtailed if you can keep up with the water needs (see section above).  However, sometimes water by itself is not sufficient to avoid damage.

• The ones most vulnerable to this type of damage are young seedlings, plants that are acclimatized to shade and the thin bark of recently pruned trees.

Therefore, if you have young seedlings in pots, put them in the shade.  If your young ones are already in the ground, then move some things around to give them shade where they are planted.  There are even cool shade tunnels made specifically to protect young  plants from the sun.

For the older plants, avoid pruning leaves and branches in the summer. This will help to protect the unaccustomed branches/trunk from getting burned.  However, if you have recently pruned your tree, or if you plants have particularly sun- sensitive branches (like fig trees), then there are other options.  One of the most direct approaches is to coat susceptible exposed branches and trunks with white latex paint.  See my earlier post on Mission Fig tree cultivation for additional info.

 

3. Kill those weeds:

• This is perhaps my favorite part of a heat wave. Those weeds in your garden are going to be exposed to the same heat stress as your cherished plants.  Unfortunately, those darn weds seem to have an unnatural resistance to extreme weather.  That weedy advantage can quickly be turned around with a simple organic spray.

 

How to kill weeds organically:

• Spraying weeds with a mix of vinegar and some soap will disrupt their ability to regulate water evaporation.  Therefore, after being sprayed with this mix, they basically dehydrate to death. This technique will work anytime, but it is most effective during very hot-dry weather.
• See my earlier article on “Awesome organic weed killer” for more specific details.

 

Be safe:

• Hot weather should be respected by all.
• Avoid working out in the extreme heat if you can.
• If you have to be out in it, plan to work in the early morning or late evening.
• And keep hydrated.