Summer is the most difficult time of the year on plants and gardeners alike. By the end of June and through July and August, especially in the South, the combination of oppressive heat and, in most years, lack of rain, stresses the ability of plants to survive and the will of gardeners to leave the comfort of an air-conditioned home, not to mention the shock of higher water bills.
If this scenario sounds all too familiar, here's a stress-relieving guide to summer gardening care. It's condensed from a class by Kacey Cloues, owner and general manager of GardenHood, an independent Atlanta retail nursery.
"Managing the health of plants in the summer is all about trying to take away the extremes — of the plants getting way, way too dry versus getting way, way too wet," Cloues told the class. "It's a huge challenge," she emphasized. That's true not just in Atlanta, but in any planting zone where the heat and drought of summer can cause garden conditions to change dramatically from one month to the next.
"The more of an edge you can take off the extremes, the easier it is for plants to remain healthy," Cloues added. "It's like raising a puppy or a child. You know balance when you swing by it. The idea is to try and find that happy medium, where a plant kind of knows 'OK, I am going to get this amount of water pretty regularly, and therefore I am going to allocate my resources here and here.' Then the plants are not getting stressed by getting completely dried out for two weeks at a time and then getting too much water. That's how to keep your plants from getting off balance."
Here is Cloues's guide to finding that happy summer medium, for you and your plants. It includes tried-and-true garden cultural advice — with a few hacks thrown in — and suggestions for tools to help ensure success, not stress!
Planting in the summer
Cloues follows the same step-by-step planting process regardless of the time of the year. But, she says, this process is especially important in the summer to help reduce transplanting shock.
Dig the planting hole wider than deep. The roots in the first year of growth are going to grow out rather than down, so remember that when you take the plant out of the pot. You're going to ruffle up the root ball to encourage the roots to stop growing in a circle. If you dig a narrow hole, when these tender new roots continue growing, they will almost immediately hit a wall of hard earth. At that point, their tendency will be to circle around that hard earth — just like they circled the pot — rather than continuing to grow laterally. A good rule of thumb is to dig the hole twice as wide as its container. Make the hole only an inch or two deeper than the container. Cloues says that failing to dig wide holes is gardeners' No. 1 mistake when it comes to planting.
Fill the planting hole with water. After you fill it, keep track of how long it takes the water to dissipate. For a smaller hole, less than 15 minutes means you have fast-draining soil. If it takes 15 to 45 minutes, that's an average time for heavy soils. If it takes more than an hour, that means you have compacted soil and the water only has little pin holes to drain out through. Drainage tells you two things: One is that it gives you a clue to how your soil at a specific site is going to drain. A second is that as you repeat the process in other parts of your yard, you will learn how different sections of your landscape drain differently. This is particularly helpful in summer because you're soaking the soil from the inside out, which will promote new root growth, as opposed to risking just getting the top layer of the soil wet when you water-in the newly placed plant.
Build a berm. Digging a wide hole will also allow you to create a berm beyond the reach of the foliage. The berm will create a basin around the plant that will capture water and direct it toward the root ball. Without the berm, you run the risk of water from rain or hoses running off the planting area.
Amend the soil
Adding compost to natural soils you've dug for a planting site is a well-known way to help enrich soils. Another perhaps less-known amendment is PermaTill, crushed shale heated to 3,000 degrees that causes the shale to expand like popcorn.
PermaTill does the same thing to landscape soil that perlite, the white stuff that looks like Styrofoam, does to potting soil. PermaTill opens and aerates garden soil to help get oxygen into the soil and to the roots. Perlite won't work in gardens because garden soil is heavy and will crush it. How much you should use depends on the how heavy your soil is and what you're planting. It could be a handful or a shovelful. In the end, that's a judgment call. PermaTill has the added benefit of deterring moles and voles from feeding on the root balls of plants.
Should you use fertilizer?
Compost is a better, milder choice for your new summer plants than fertilizer. (Photo: SuSanA Secretariat/flickr)
In a word, don't! Don't fertilize new summer plantings of perennials, shrubs and trees. They are in shock and fertilizing can contribute to this. In particular, plants that are suffering from drought or are stressed by insect or disease problems should not be fertilized.
Instead of fertilizer, add compost such as worm castings, hen manure, mushroom compost or compost from your compost bin. The idea is to feed your new plants but with something that's very mild. Hen manure and worm castings, for example, are 1-1-1 in terms of the nitrogen, phosphorus and potassium ratio. Because they are extremely mild and slow release, they aren't going to shock the roots. Compost helps helps in the same manner and it has the added benefit that it contains moisture.
For mature plants showing drought stress, make holes around them with a soil aerator or a metal rod 3/4-inch in diameter. Then dump out some worm castings or compost and with your fingers, rake them over the holes. The particles will go down into the holes and help bring moisture and nutrients several inches below the surface of the soil where the roots are going to take most advantage of the compost. For small plants, use the metal supports on surveyors' flags or something similarly small to make the holes. You can also do this anytime of year.
Annuals are an exception to summer feeding. They grow fast, bloom profusely and are hungry!
Providing a layer of organic mulch will help regulate soil temperatures, retain moisture and control weeds. It's important, though, to follow a few basic rules to prevent the mulch from doing more harm than good. The most important of these are to leave a gap of several inches between the stems of perennials or the trunks of trees and shrubs and don't make the mulch layer so thick that water can't penetrate it.
There are also some guidelines for matching mulch with the different planting situations gardeners can encounter. The idea is to choose a mulch that is most likely to remain in place or that is best suited to the varying needs of different plants. If you're on a slope, for example, pine straw tends to work better than bark. Small bark tends to work well in flower beds and vegetable gardens — especially raised beds, because these plants tend to be small when you plant them. Mulch will not do well in areas that aren't flat or are susceptible to washes because it can float away in a heavy rain. Use larger bark around trees and shrubs.
Rubber mulch should be avoided because it can leach unwanted additives into the soil, it tends to get hot and raise the surface temperature of the soil and it doesn’t break down. Fall leaves can be used for mulch as long as you shred them before applying them to the garden. Hay or wheat straw comes with the caution that either can spread weeds.
Clover can be a beneficial weed to your garden. (Photo: BlueSkyMomonga/flickr)
While weeds compete with desirable plants for water and resources in the soil, it would be a mistake to think that all weeds are bad. Some can serve a useful purpose.
Clover, for example, serves the beneficial purpose of collecting nitrogen in its leaves and sending that nitrogen through its stems and into the ground in a process called nitrogen fixing. Other plants, ornamentals or vegetables, depending on where the clover was growing, absorb the nitrogen supplied by the clover and use it to build strong stems and leaves.
Henbit is another that provides advantages; that's because henbit is a handy food and nectar source for pollinators and other beneficial insects and is even edible for humans. It does grow quickly, but it's really easy to remove from unwanted areas, and it can be readily managed to keep it under control. It mingles quickly among flowering perennials, herbs and vegetable plants. In August, both clover and henbit have the added benefit of serving as a mulch that will help retain water. If it’s been a really dry summer, pulling them out of your lawn or garden can expose more of your landscape to dryness and evaporation.
Weeds that should be your first battle are annuals that produce seed heads. These weeds, or their seed heads, need to be removed before the seed heads burst and spread thousands of seeds into your lawn and planting beds. Other types of weed for your worst offender list are those that made deep tap roots. The bigger the tap root, the more resources that plant is going to appropriate from your garden. Among these, dandelions are easily the worst offender. Use a long, narrow trowel or hori-hori (a garden digging knife) to dig around the tap root and lever out as much of the thick, starchy part as possible. (It's worth noting that pulling deep-rooted weeds is significantly easier after a good rain when the ground is soft!)
Henbit can grow quickly, but it's easy to manage. (Photo: 3w4v/flickr)
A website from the University of Arkansas will help you identify the most detrimental weeds. The site says these are Arkansas weeds, but the list contains many common weeds that are problems no matter where you live. Georgia garden expert Walter Reeves also has a helpful list of weeds plus sources for more information about weeds on his site.
If weeds are coming up through your mulch, an organic and back-saving way to remove them is to rake the mulch back, chop down the weeds at the soil line with a hoe or cultivator, apply white vinegar using a regular kitchen spray bottle and rake the mulch back into place. If you're looking for an extra organic remedy, place newspapers or cardboard on the surface before raking the mulch back into place. This is an environmentally friendlier approach than using herbicides. Pre-emergents like Preen contain chemicals and aren't organic.
Only use landscape fabrics as a last resort to prevent weeds. While this method will control weed growth, it will also prevent sunlight or oxygen from reaching the soil. Chances are nothing will grow under the fabric, including beneficial soil microbes and earthworms.
This is arguably the most important aspect of summer garden care — and not for the obvious reason that plants need water during the long, hot and dry days and months of summer. You not only have to water your plants, you must water them properly. Believe it or not, there are right and wrong ways to water your lawn or garden.
It's much more effective to water plants slowly every few days, for example, than it is to give them a light sprinkling every day. The idea is to give a deep soak so water seeps down to the bottom of the root ball. With frequent light watering, the deep roots won't get water, will die of thirst and the plant will be left with a thin mass of surface roots. This is a condition that can cause winds to topple trees during storms.
The wilting hour
Even with proper watering, the leaves of many plants will droop in the heat of the day. Hydrangeas, in particular, are famous for this. This phenomenon will occur at the same time every day. Cloues calls it the wilting hour.
If you're following a watering regimen, resist the urge to water your plants when you see this happen. "It's kind of like us sweating," Cloues said. "The plants are conserving resources by not sending as much energy, water, food and other resources out to the ends of the branches. It's almost like the plants are shutting down those avenues to protect the core. As soon as it cools off in the late afternoon or evening, those vessels open right back up and the leaves will return to normal."
Drooping leaves can be confusing because plants will also do the same thing if they've been overwatered. The best way to determine if a plant needs water is to poke your finger or a trowel into the soil. If it comes out covered with gooey nice dirt, the ground is moist and you don't need to water. If it comes out clean or just a dusting of dry soil, you need to water. It's like baking a cake and testing the layers to see if they are done.
Soaker hoses need the correct water pressure to really benefit your garden. (Photo: Alan Levine/flickr)
Cloues is not a fan of irrigation systems. She thinks gardeners become too reliant on them and lose touch with their plants. To stay more engaged with your plants and be more responsive to their needs, she recommends hand-watering or watering with more standard tools, such as soaker hoses (unless you are managing a large tract of land).
Soaker hoses are one of the best safety nets you can set up for yourself. In parts of the South, they can even be left in place in the winter. The trick with soaker hoses, Cloues said, is not to use more than a 100-foot section at a time. The hoses are specially designed to have accurate pressure for that specific length of hose. Meaning, a 100-foot soaker hose is designed to supply the correct amount of pressure to push the water out through the tiny holes along its entire length. Adding more hoses changes this pressure and can render the ones furthest away from the spigot ineffective or even completely useless. If you need to get a soaker hose to an area that's more than 100 feet from the house, attach a regular hose to the spigot and then attach a soaker hose to the regular hose. You can also attach a splitter to the spigot to run soaker hoses to different parts of the garden.
Getting the correct water pressure is perhaps the biggest challenge of soaker hoses. The pressure on most home spigots is 50 psi. Most soaker hoses operate best at 10 psi. Luckily, many soaker hoses come with their own pressure regulator; it's a disk on the end of the hose where it attaches to the spigot. If you have an old hose, it may not have that. This is something you should troubleshoot that from the beginning. Sales staff at stores that sell soaker hoses should be able to help you with any questions you have about regulating pressure. One way to tell if the pressure in a soaker hose is too strong is if the hose is spraying water into the air like a sprinkler hose rather than just allowing the water to ooze out of the hose.
To determine if every part of your garden is getting sufficient water and how quickly, you can measure how much water the soaker hose is supplying by setting tuna fish cans or fruit cocktail cans, both of which are about one-inch deep. Lay the hose over the cans and see how long it takes to fill them up. If the cans fill up faster closer to the spigot than ones furthest from the house, you know you have a pressure problem. In this case, first, check to make sure that the pressure regulator disk inside the soaker hose is in place or not damaged or leaking. If it's in good working order, the next step may be to purchase a pressure regulator to attach to the spigot itself. These are available at hardware stores and online.
Soaker hoses are far better than sprinklers for gardens because they apply water directly to the soil surface, resulting in only a minimal loss of water to evaporation. Only use a sprinkler on turf, and be sure to do that in the morning before the heat of the day. You can still use tuna or fruit cocktail cans to measure water to make sure you are giving your lawns an inch of water a week.
Tips on setting up soaker hoses
Soaker hoses like sitting on top of the soil, releasing water to the plants. (Photo: J.H. Fearless/flickr)
Soaker hoses should be put on the top of the soil but under the mulch. Don't bury them in the soil. Chances are pretty good they will eventually become clogged if buried. If you have well water, be aware that this water will likely have more sediments than municipal water and will often clog a soaker hose pretty quickly.
When setting up soaker hose for several plants, put a loop around each plant — or more than one loop if the plants are water-loving ones, like a swamp hibiscus. You can use big landscape staples to keep the hose in place as you run the hose from one plant to another.
If you're using a soaker hose in a vegetable garden with rows of plants, run the hose up one side and snake it back down the other.
In a garden bed where plants are not in rows, you need to be a little more creative with soaker hoses. It’s better to make a circle than an 'S' throughout the bed. With an 'S' curve there's a good chance you'll see some plants start to die during extremely dry conditions.
With foundation planting and plants in rows, run the soaker hose down back side of root balls, take it around the edge end of the row and come back down the side.
What about a drip irrigation system?
If you have an irrigation system and are handy, you can convert that to a drip irrigation system. Drip irrigation materials are available at the box stores, sometimes in the outdoor section, and sometimes with plumbing supplies. These systems involve brown or black tubing of different widths. You can create a system of tributaries with a drip irrigation system, allowing you to cover more areas of your garden. You can get as involved with drip systems as your imagination, budget and handyman skills permit. Drip irrigation, for instance, can work in pots or hanging baskets in addition to the landscape.
The five-gallon bucket trick
Newly purchased trees that are balled-and-burlapped, 10 feet tall and 2-3 inches in caliper are more susceptible to transplant shock than a tree in a five-gallon pot. Large new trees will need five gallons of water per inch of caliper twice a week for the first year. Caliper is the width of the trunk two feet above the ground. For example, if a tree has caliper of two inches, you will need to give it 10 gallons of water at least twice a week. To figure how long it takes to fill a five-gallon bucket with water (buckets are available at box stores), start with a quarter turn on the spigot and see how long it takes to fill up the bucket. If it is painfully slow, then try a half turn on the spigot. if it takes 20 minutes, using the above example for a tree with a two-inch caliper, then hand-water the tree with a slow-running hose for 20 minutes twice a week. Be sure to remember that the best to water slowly is to allow the water to seep down to the bottom of the root ball. Remember, too, that you can lay the hose on the ground by the tree. You don't have to stand there the whole time!
"Newly planted" could also be a tree or any plant that you are transplanting, not only ones that have just come home from the nursery. If you are dividing hostas, for instance, the clock starts over again with plant care even though the plants may be at a mature size when you separate and transplant them.
This is a case where more is not better. Keeping a soaker hose on too long will cause roots of young plant roots to stay near the surface. It can also cause mature plants to develop weak roots. It can be a tough to tell yourself to step away from the hose, but you have to do it!
Watering pot-bound plants
Generally, when water runs through a pot it means the soil is saturated and the plant doesn't need more water, and sometimes the opposite is true. Occasionally, plants you purchase from the nursery can be pot bound. This means that the roots have grown so aggressively that the pot is a mass of roots that have even pushed some of the dirt out of the pot.
An indication of this condition can be a mat of roots that have grown through drainage holes on the bottom of the pot. In this instance, it's not unusual for the water to immediately flow through the pot and out the bottom. When this happens, pull the plant out of the pot and check the root ball to see if it is wet. Chances are the core of the root ball is bone dry even though you've just watered the pot.
What has happened is that the root ball is so dry it couldn't absorb the water and the water simply ran around the inside of the pot and out the bottom. To set things right, partially fill a 5-gallon bucket with water and place the root ball in the bucket. Put enough water in the bucket so that the water comes to the top of the root ball. Leave the plant in the bucket until the root ball is saturated. When you lift the plant out of the bucket, you will feel the difference in the weight of the root ball when it has become wet throughout the root mass. Next, ruffle roots on the side of the root ball, but not too much because you don't want to further shock it. Pull off roots that may have matted around the outside of the bottom of the pot. You are now ready to plant this new plant following its provided directions.
More summer watering techniques
Here are additional tips on summer watering techniques.
Don't wet leaves when watering outdoor plants. Plants do not need water on their leaves. In humid climates like the South, watering the leaves can even spread of fungal spores. And on sunny days, every droplet of water acts like a magnifying glass that can result in "burns" on the leaves.
Get to know your plants. Some plants have deep tap roots while some have shallow fibrous roots. Knowing which has which is important because plants have different watering needs based on their root structure. Plants with deep tap roots need more water than those with shallow roots. If you water everything exactly the same you may not be giving plants that are on either end of the spectrum what they need. The planting technique described earlier about filling planting holes with water and timing the drainage is a clue about that plants based on their root structure and which watering needs will work best in different situations. An example is an agave. You shouldn't plant it in an area that drains poorly as it is a plant from an arid region.
Watering on a slope. To remedy a water runoff problem, water slowly on the uphill side of the slope and watch to see if water is soaking into the ground around the root ball. You can even poke little holes in the soil to let the water drain in or berm up the planting site or create a terrace. These techniques will slow down the flow of water down the slope.
Tree gators. These are green or brown bags that wrap around tree trunks and can be filled with water from a hose and then fastened with zippers or Velcro. They have punctures in the bottom that direct water directly onto the root ball.
Water crystals and glass bulbs. If you are using crystals in potted plants, be sure to put them in the bottom of the pots. They make jelly-like globs and are unsightly on the surface of pots. Be aware that glass bulbs that drain into potted houseplants might become clogged with dirt, and that can reduce their effectiveness.
The milk jug trick. If you are going on vacation, consider putting a few pin holes in the bottom of a milk jug, fill the jug with water and place it on your pots. The water will drain out while you are away. Nails that go with picture hangers can be used to make the pin holes. It's a good idea to test this trick out a few weeks before your vacation to determine how many pin holes to create and how long it takes the water to drain.
"You can keep things simple or you can get fairly involved," Cloues told the class. "You'll learn as you go along that different things work in different situations. Experiment and most of all have fun with your summer garden care."