How to help plants cope with extreme heat?

[blueberr]

Hi, my lavender plant, blackberry bush, and rosemary look like they are dying. I'm unsure what to do about watering and coping with Adelaide weather. These are young plants.

Thank you for tips on the blueberry plants.

Kind regards Denise xxx

 

 

 

[MitchellMc]

To help figure out why your lavender, blackberry, and rosemary aren’t coping with the Adelaide heat @blueberr, we need a bit more information about how you’ve been caring for them. First, could you tell us how much sunlight each plant is getting daily, and whether it’s direct or indirect sun? Second, how often and how long do you water them? Third, what is the drainage like in their pots and does water flow freely out the bottom?

From the pictures, the soil in the pots looks very wet, which can be just as harmful as underwatering. Too much water can quickly stress or even kill young plants. Once you give more details about your watering routine, the first step would be to let the soil start drying out between waterings. The soil should stay somewhat moist but never remain saturated. In Adelaide’s heat, you might water every two to three days, depending on how much direct sunlight they receive, making sure the soil has time to dry out in between.

I also noticed the plants are in a tub. Are they outside in the garden or indoors? That will affect how much sunlight and airflow they get, both of which are important for their health.

Looking at the plants, the blackberry appears the most stressed and may be difficult to save if conditions don’t improve. Rosemary is fairly hardy but doesn’t need much water, so overwatering is likely the main issue. Lavender can usually recover if overwatering is addressed, and it gets good sun.

Finally, check that the pots have adequate drainage. Roots need a wet-dry cycle to thrive as they like the soil to be moist but cannot survive in constantly saturated soil. Adjusting your watering and ensuring proper drainage are the most important steps to give these plants a chance to recover. 

Also, the other thing I wanted to point out is that they appear to still be in nursery transport-sized pots. This makes it much harder to regulate watering, then say if they were in a slightly larger pot or a garden bed. It's difficult to keep plants alive in the original pot they come in.

Here's a helpful guide: How to diagnose a sick plant.

Please let me know if you have any questions.

Mitchell

[blueberr]

I brought them inside due to the heat. I had just watered all of the plants, which is why they look wet. I usually have them on a table undercover, but they still get sunlight.

Do I need to plant them in another pot, like terracotta pots?

[JacobZ]

Hi @blueberr,

During intense heat like we have been experiencing lately, sheltering your plants inside can certainly help, but they should be returned to their original position when possible to ensure they are getting the sun and airflow that they need.

Moving your plants to new, larger pots with fresh potting mix is definitely going to be a good idea as it will allow them room to grow and provide nutrients to assist with this growth. 

You want to grab a pot that is roughly one size up from their current size, so if they are in lets say a 110mm pot, you would grab a 150mm pot, or if they are in a 150mm pot, you'd grab a 210mm pot. Using a pot that is too large too soon means there is more soil than roots, so the mix stays wet for longer and can lead to root rot. It also encourages weak root development because the plant does not need to actively search for water and nutrients.

Terracotta pots will work with both types of plants, but they are porous and allow water to drain through them, so they can dry out quickly in hot and windy conditions. If you want to simply water them once or twice a week, then a self-watering pot with a reservoir at the base would be better.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob