Sarah Robertson Columnist | Posted: Saturday, July 21, 2007 10:00 pm
Daytime temperatures are reaching a point where many plants are definitely feeling the heat.
Even species that love hot weather (lantana, cucumbers, geraniums, petunias, rubeckia and crocosmia, to name a few) are occasionally wilting by late afternoon when the thermometer climbs to 90 degrees F. or more.
Most heat lovers recover just fine by early evening, as the air cools. But species such as hydrangea, impatiens and hostas - not to mention hanging baskets - will appreciate additional watering to help them recover.
As I write, the thermometer outside our kitchen window thermometer reads 96 degrees. In the shade! The entire garden received water earlier this morning and I'll spot water certain vegetables (lettuce, late peas, sprouting beans) in mid-afternoon. The hanging baskets will get another deep drink in early evening, when the sun has shifted to another part of the garden.
Hot weather is definitely on the minds of some gardeners, so find a cool spot to relax and let's get to it.
A mid-July Q&A
Question: "Our friends have just finished a major home and garden remodel. Their landscaper is getting ready to seed new lawns in both the front and back yards. Isn't it too hot at this time of year to plant grass seed? I'm worried that their lawn will fry in the heat."
Answer: I understand your concern. It's hard to conceive of a newly planted lawn thriving in the hot temperatures so typical here during July and August. But lawns seeded during summer heat can survive and even thrive. It simply requires care on the part of the homeowner to ensure that the seed stays moist during the germination process.
It's actually not uncommon to see lawns being seeded during July and August. Sure, earlier in the spring or later in the fall would be better - it's cooler, which means less frequent watering, and those tenacious summer weeds are less apt to be a problem. Sometimes, however, summer ends up being the only time a homeowner or their landscaper can do the job.
Now, about grass seed. There are two main reasons people prefer seed over sod: it's a lot cheaper (25-30 cents per square foot for sod versus about 2 cents per square foot for seed), and the choice of grass cultivars and blends to fit specific needs (sun, shade, part shade, boggy ground, dry shade, etc.) are infinitely broader when you go with seed.
Grass seeds germinates best when the soil temperature is at least 55 degrees F., usually anytime between mid-April to mid-October. And yes, that includes summer.
Right now, extra warm soil means your friend's grass seed will germinate quickly and relatively evenly. The drawback is that high air temperatures could dry out the seed before it roots properly.
The key to success? Water, water and more water! The idea is to keep the soil and seed consistently moist, but not sopping wet. This step is critical during high summer, when scalding sunlight, drought and high temperatures can ruin any newly seeded lawn that isn't kept damp.
Watering several times a day for three weeks is about what it takes at this time of year to get grass seed off to a good start. Reduce watering to once daily after the new grass tops one inch in height, but beef up the frequency if the soil becomes obviously dry due to a spell of hot weather.
Some professionals like to spread a light mulch over the grass seed to hold it into place and keep the soil moist. Others prefer just rolling it into place and not covering it. Either method works.
It's also helpful, but not absolutely necessary, to apply a mild organic fertilizer when seeds are sown. Apply again in three to four weeks, since all of that initial watering will have leached that first application deeper into the soil and beyond the reach of young grass seedling roots.
Mow when the grass reaches 21/2 to 3 inches in height. After a new lawn has been mowed three times, put it on a watering schedule of at least one inch per week.