Advice on how to have success growing second and third crops
after harvesting your spring vegetables
There is nothing I like more than being out in my vegetable garden in late March and April, working my soil in anticipation of a bountiful harvest. Temperatures at that time are usually splendid and I have no problem enjoying one of my favorite pastimes. As I fast-forward several months into the summer, my enthusiasm begins to wane as 90-degree days and high humidity begin to plague me. Not only do I have a problem staying active in such unbearable temperatures, but my plants always seem to be suffering as well. While many gardeners throw in the towel during the hottest part of summer and recline back in their air-conditioned homes, there is still an opportunity and possibility to extend your harvest season all the way until the cooler months of fall.
When talking about hot-temperature gardening, we need to examine what is happening to our plants. Just like you and I perspire more frequently during hot temperatures, plants also sweat in a way by transpiring. As plants move precious water and minerals through their systems, they transpire the moisture through their leaves more frequently as the temperature escalates. This makes it even more critical to keep a careful eye on your vegetable irrigation as we hit temperatures above 85 F. It only takes a day or two of drought or poor water management and you can potentially lose the crop. Pay particular attention to raised-bed gardens; they will dry out more quickly than conventional planting.
Because of the high temperatures, evaporation of the moisture from the soil will be more extreme. For this reason, irrigation should be delivered through soaker hoses or a drip system rather than overhead watering. It is also recommended to irrigate between 9 p.m. up until 9 a.m. During this time period you will experience less evaporation and allow the foliage to dry off. This will lead to fewer instances of disease.
Plants such as okra may love the hot, humid environment, but you will need to keep a close eye on water loving plants such as corn, cucumbers, and squash.
Another way to survive the dog days of summer and produce a healthy crop is to continue staggered new plantings of vegetables every few weeks up through the middle of summer. This gives you fresh, healthy crops while you continue to harvest from your older and possibly exhausted plants.
As a crop fizzles out in the garden, it is important to remove it and perhaps add it to your compost pile. Leaving expired plants in the garden can lead to the introduction of diseases and invasion of possible insects.
Planting new seeds or transplants during the hot temperatures of summer is a bit more challenging. You will need to nurse them along for the first week or two, supplying adequate irrigation. You may even want to consider using some type of screen or shade material to provide them relief in the hot afternoons for a couple of weeks as they acclimate to their new hostile environment.
You have probably noticed an increase in disease and insect activity in the heat of the summer. While 90 percent of the bugs you see may be beneficial, the bad guys are more likely to show up during the hot months. This is when you need to be scouting your garden frequently for any signs of an outbreak. While I don’t normally recommend preventive insect sprays, you may need to apply a product if you spot existing insect damage. I begin by applying some type of organic insecticide that is more environmentally friendly, but still effective. I prefer to spray insecticide applications late in the day, when there is less chance of hitting beneficial pollinators that are in the garden. Pollinators tend to fly early in the morning on sunny days, so you should avoid spraying at that time.
Tomatoes are perhaps some of the most difficult to keep alive late in the season because they are so susceptible to problems. In order to extend the life of your current tomato plants, plan on pruning them frequently. I like to eliminate most of the lower branches so that none of the foliage touches the ground. I also pinch out the suckers between the main branches and eliminate some of the non-bearing structure to allow more air and sunlight to penetrate the plants. Just take care not to over prune your tomatoes because the actual fruits benefit from the shade provided by the foliage.
In late summer, mulch is a gardener’s best friend. I use various types of mulch throughout the garden season to help me keep weeds at bay and hold moisture in the soil. Newspaper laid three layers thick can be excellent mulch around your plants. After laying it down, I immediately wet it to keep it in place. I then cover it with an organic mulch of some type of straw or bark to hold it in place and provide an extra layer of protection. Weeds do not mind the heat or humidity at all, and tend to grow rapid during the summer. You might consider using a combination of mulch and hand pulling or tilling to keep them under control. Weeds are always easier to remove when they are young. The drip irrigation we mentioned earlier will also help in your weed management. Drip irrigation applies the water directly to the target plant, and does not water all of the areas between rows like overhead watering does. Remember that overhead watering is watering your plants, but also giving your weeds an energizing drink.
Remember to keep an eye on the fertility needs of your summer garden. While the initial phosphorous and potassium that you applied earlier in the season may still be available, the nitrogen is most likely long exhausted. Continually bearing plants such as tomatoes, squash, peppers, and okra will need additional nitrogen every two or three weeks throughout the growing season. Target the application close to the plants but not right next to the stem. Sprinkle the fertilizer evenly 6-8 inches away from the base of the plant. It makes good sense to irrigate soon after applying the fertility so that the plant may begin to absorb it quickly. Care should be taken when using liquid fertilizers – do not apply too much nitrogen. Liquid nitrogen formulations can be difficult to calibrate and apply correctly. I recommend using them at half the labeled rate. Remember that the amount of time you spray each plant can double or even triple the rate of application.
One final piece of advice is to harvest your garden frequently. Summer vegetables can develop rapidly. If left on the vine too long, that can signal the plant to shut down, because it has accomplished its goal of reproducing seed. By harvesting frequently, we accomplish three things. We trigger the plant into continuing to reproduce; we harvest a vegetable that is more tender and tasty; and by harvesting a young vegetable, we help prevent insect invaders that hone in on older, maturing fruit.
I am a cool weather kind of guy, and I don’t particularly enjoy hot, humid weather. However, my appetite is stronger than my desire to stay cool. I love the taste of fresh vegetables, and I want them all season long. You too can enjoy an extended summer harvest if you can bear a bit of the nasty temperatures and do a few of the preventive measures in this article. And the bonus is that you get to eat the delicious harvest in the comfort of your air-conditioned home.
A version of this article appeared in a June 2016 print edition of State-by-State Gardening.
Photography courtesy of Bob Westerfield.