We are blessed with mild winters and a year-round growing season. But summer is a garden’s, and a gardener’s, worst enemy. The combination of heat and humidity is hard on our plants. Even resilient natives can look a little weary before it’s all over. But there are things we can do to make it easier on the garden while we wait for the pleasant days of fall.
Water – It goes without saying that natural rainfall is best for a garden. The Greater Houston area receives sufficient annual rainfall to sustain a garden – if only we could just regulate when it fell! We seem to always be in the feast or famine cycle when it comes to rain.
All gardens will require supplemental water from time to time. Less frequent, deep soakings are better for a garden than frequent shallow watering. Deeper watering encourages plants to develop roots deep in the soil where moisture remains longer, and the soil is cooler.
If you can, water in the early morning. It’s cooler, which reduces evaporation. The plants will absorb the water they need to get through the heat of the day. The next best time is late evening, after temperatures cool down a bit.
If you water in the evening, try to keep the foliage dry. It’s tempting to give plants a cooling shower, but this can promote fungal diseases. It’s a myth that water droplets create sunburn. They don’t stay on the surface long enough for that. If you do want to just cool everything off, do it early so the foliage can dry out quickly.
Soil Texture – Soil that has adequate organic matter holds more water after rain or irrigation and releases it back to the plants more efficiently. Soil should have a minimum of 5% – 10% organic content, but your long-term goal should be to reach 25% – 30%.
The best form of organic matter is compost. Keep in mind that not all compost is created equally! Be careful of your source and buy the best quality product you can afford. Remember that these materials need to be replenished annually, maybe even seasonally, depending on decomposition rate.
Nutrients – Following a consistent organic program supports the soil food web – the biosphere of beneficial macro- and micro-organisms that works with plants to provide nutrients and decrease soil borne pathogens. Regular applications of a balanced organic fertilizer such as Arbor Gate Organic Food Complete are the foundation of this program.
Other supplements such as greensand, rock phosphate, and other minerals can be added if deficiencies are identified, or for plants that have specific requirements. A consistent organic program will keep your plants healthier year-round, which will help them deal with both summer stress from heat and drought and winter stress from cold and drying winds.
Mulch – Mulch serves a number of purposes, one of which is keeping the soil cooler in the summer. A 3” layer of organic mulch can reduce soil temperatures by as much as 25° – 30° F. That’s a LOT of temperature 
moderation. Mulch also reduces evaporation, so the supplemental water you apply will be more effective.
You can apply mulch anytime, but summer is the worst time for the gardener’s comfort. It’s a hot chore. It is best to apply mulch in one of our cooler seasons. However, if I did not have mulch on a bed, I would bite the bullet and get out there in the cool of early morning or late evening to spread it before I would let the bed bake for the summer.
Foliar Feeding – If we have followed all the practices above, our plants will be healthier and more resilient, but things can still go wrong in the best of circumstances. And if you are still working on your soil quality and mulching, we still need to get your plants through summer stress!
We turn to electrolytes when our bodies are weakened by heat stress. Believe it or not, plants require some of these same minerals for the same reasons. Timely application can make all the difference. Plants absorb these minerals very quickly through their foliage – faster than through the root system – so a foliar application is recommended.
The easiest foliar feed is just a liquid seaweed solution made from kelp. Sea water is mineral rich. Kelp is a sea plant that absorbs this “mineral soup” and stores it in its tissues. Those minerals remain when it is harvested and processed into a garden product.
Dilute as recommended on the bottle. Spray the foliage until it is dripping off. Make sure to spray the undersides of the leaves as well. Follow this with a drench in the root zone. For consistent summer support, apply bi-monthly to the foliage and monthly as a drench. This does not replace your regular fertilizer. This is a “boost” that should be applied in addition.
Veggie Booster – You can take this a little farther in the veggie garden. We ask a LOT of our veggies to produce consistent top quality in the summer heat! This “tonic” uses a combination of Epsom salt, Liquid Seaweed (kelp), and SuperThrive®.
Despite the name, Epsom salt is not a sodium salt like table salt, but rather a source of minerals magnesium and sulfur. Gardeners have used Epsom salt for decades and it has many uses in the garden. Magnesium plays a crucial role in photosynthesis – the process by which the plant converts light energy into chemical (food) energy. There are some exaggerated claims about Epsom salt out there. We can weed those out from its practical applications and use it in a commonsense way.
Seaweed (kelp) provides roughly 60 trace minerals plus amino acids and enzymes. It enhances root development, stimulates microbial activity, and promotes the production of auxins (natural plant growth hormones).
SuperThrive® is a combination of vitamins and plant hormones. It is not a standalone fertilizer but can be added to fertilizers. It is well known to reduce transplant shock.
The “tonic” recipe for the veggie garden is:
• 5 gallons water
• 2/3 cup Liquid Seaweed
• 2/3 cup Epsom salt
• 1 Tbls SuperThrive®
Two-thirds cups is based on a recommended application rate of 2-Tbls per gallon of water of the Liquid Seaweed and Epsom salt – 1/3 cup is 5-1/3 Tbls. If the products you use recommend more or less than this, adjust as required. You can substitute Garrett Juice for the Liquid Seaweed but you will need to increase the amount to 1.1/4 cup per 5-gallons. Garrett Juice has compost tea and horticultural molasses as well as seaweed.
Water your plants thoroughly the day before application. Then apply the tonic as a drench, wetting the root zone of the plant. You will use ½ – 1 gallon for shrubs, and less for perennials, vegetables and bedding plants. It will take several days to see results. How often to apply depends on how stressed the plant is, how long the heat lasts, and the general health of the plant in the first place.
Container plants may benefit from using this tonic weekly, but if you choose to do this, dilute it by half with water. This follows the “weakly, weekly” practice and can keep easily stressed plants, like root-bound ferns, happy through the summer.
With any supplement, there is a tendency to think that if a little is good, more is better. We do have to remember that any excess we apply can leach out of the soil and end up in the watershed. It is best to apply conservative solutions on a regular basis rather than a large amount all at once.
Tonics – If we have followed all of the practices above, our plants will be healthier and more resilient, but things can go wrong in the best of circumstances. If you have not yet taken the above steps, you still have to get through this summer. You can spend some time amending the soil and mulching this fall and winter. In the meantime there is a “tonic” that assists plants through their heat stress – a combination of Epsom salt, Liquid Seaweed (kelp), and SuperThrive®.
Despite the name, Epsom salt is not a sodium salt like table salt, but rather a source of the minerals magnesium and sulfur. Gardeners have used Epsom salt for decades and it has many uses in the garden. Magnesium plays a crucial role in photosynthesis – the process by which the plant converts light energy into chemical (food) energy. There are some exaggerated claims about Epsom salt out there. We can weed those out from its practical applications and use it in a common sense way.
Seaweed (kelp) provides roughly 60 trace minerals plus amino acids and enzymes. It enhances root development, stimulates microbial activity, and promotes the production of auxins (natural plant growth hormones).
SuperThrive® is a combination of vitamins and plant hormones. It is not a stand alone fertilizer but can be added to fertilizers. It is well known to reduce transplant shock.
I make up a “tonic” that gives heat stressed plants a little relief. It is:
- • 5 gallons water
- • 2/3 cup Liquid Seaweed
- • 2/3 cup Epsom salt
- • 1 Tbls SuperThrive®
Two-thirds cups is based on a recommended application rate of 2-Tbls per gallon of water of the Liquid Seaweed and Epsom salt – 1/3 cup is 5-1/3 Tbls. If the products you use recommend more or less than this, adjust as required. You can substitute Garrett Juice for the Liquid Seaweed but you will need to increase the amount to 1.1/4 cup per 5-gallons. Garrett Juice has compost tea and horticultural molasses as well as seaweed.
Water your plants thoroughly the day before application. Then apply the tonic as a drench, wetting the root zone of the plant. You will use ½ – 1 gallon for shrubs, and less for perennials, vegetables and bedding plants. It will take several days to see results. How often to apply depends on how stressed the plant is, how long the heat lasts, and the general health of the plant in the first place.
Container plants may benefit from using this tonic weekly, but if you choose to do this, dilute it by half with water. This follows the “weakly, weekly” practice and can keep easily stressed plants, like root-bound ferns, happy through the summer.
With any supplement, there is a tendency to think that if a little is good, more is better. We do have to remember that any excess we apply can leach out of the soil and end up in the watershed. It is best to apply conservative solutions on a regular basis rather than a large amount all at once.
