Where the rain doesn't reach
Even if it rains in the summer, it can be a challenge to keep your plants healthy.
Heavy rains don't always mean that enough water gets where it's needed, such as under and around the roots of your plants.
Young or newly planted plants are especially susceptible to these fake outs.
The problem is where it never rains.
Topping that list is under roof overhangs, which can extend more than two feet from the walls and keep rain from falling on anything planted close to the structure.
Keep an eye on plants in these locations, as they may still require watering during rainy weather, and consider moving them farther away in the fall, if possible, to alleviate this problem in the future.
The second most secretly dry place is under a tree…especially a big one.
First, raindrops are intercepted or absorbed by a thick canopy of leaves, limiting the amount of water that actually reaches the ground.
Next, the rain that passes through the tree canopy must seep through the layer of mulch that most people put around the plants below the tree. Mulch is effective at keeping moisture in the soil, but without regular rainfall, the tree's roots will eventually soak up the moisture.
Depending on the thickness of your mulch layer (which should be about 3 inches around shrubs and no more than 1 to 2 inches around perennials and ground covers), it may take an inch or more of rain to seep through the mulch layer and reach the soil below.
By the way, rain absorbed by mulch affects everywhere, not just under the tree.
Check the soil under your tree after rains to see how much water has actually soaked into the soil, and when you plant new plants under the tree, keep a hose handy to compensate for soil blockage and root competition caused by the rain.
The third problem is banks and slopes.
Summer storms tend to bring short, heavy downpours rather than gentle rainfall all day, causing water to run off rather than soak.
If your bank is covered in shredded hardwood (the most common type, which has the added benefit of being woven to help it stay in place on slopes), you may notice that rain runs off at first. This is because the woven layer forms a dense surface that repels water until enough water breaks the surface tension and seeps through.
South- and west-facing banks dry out especially quickly, so even if heavy rainfall does soak the soil down to the root zone, the soil may dry out again within a few days.
Potted plants will dry out even faster.
Even after a generous rainfall, the soil in the container may dry out again after a day or two.
When checking plants, your index finger works better than any gauge for judging how moist the soil is a few inches down. Alternatively, buy a moisture meter that you insert into the soil.
If you have a pot, tilt it slightly and weigh it – a dry pot will be noticeably lighter than a damp one.
Read George's 8 tips for watering your plants in summer. Read George's post explaining why getting watering right is so important. Gypsophila is a perennial plant and one of the best garden plants to cut and dry.
How to harvest and dry cut flowers
Home-grown cut and dried flowers have become popular recently, with midsummer being the peak harvest season.
DIY bouquets offer gardening enthusiasts a way to preserve and enjoy their handmade creations indoors, plus they make lovely (and inexpensive) gifts for non-gardening friends and neighbors.
The National Horticultural Association offers these tips on how to harvest, dry and process home-grown flowers:
1.) Harvesting. Cut the stems when the first flowers mature. Don't wait until the plant has reached its peak (or longer).
The best time to harvest is in the morning on a day with a slight breeze. When cutting, remove as many stems as possible and make a clean diagonal cut with sharp pruning shears.
2.) Tie them in bundles. To dry most flowers, tie them together with rubber bands at the stem ends so that the bundle is no wider than an inch to an inch and a half.
Hang the bundles upside down in a cool, dry room — a spare bedroom or large closet is best — but avoid damp kitchens, bathrooms, hot attics, and damp basements.
The exceptions to the advice to dry upside down are sunflowers and other large, prolific flowering flowers such as dill, fluffy grasses and Queen Anne's lace, which are better dried upright.
A low light location out of direct sunlight is best. A dehumidifier set on a low fan speed will help dry it out – the faster it dries, the better.
3.) Hang to air dry. A good way to hang large bundles is to hang a 1.5cm diameter horizontal rod or pipe from the ceiling. Alternatively, use a tripod or two high-backed chairs to support the rod. You can also make a cheap hanger out of a bent paper clip.
Place newspaper or a tarp on the floor underneath to catch fallen leaves, seeds and petals.
Hang the bundles far enough apart to allow for good air circulation.
Drying usually takes 10 to 20 days, depending on the flower. You'll know they're ready to dry when the stems break and you can pull a flower or two apart to see if they're dry inside.
4.) Other drying methods. While most flowers can be air-dried in bunches, more delicate, water-hungry flowers like anemones, daisies, pansies, and zinnias are best dried using silica gel or a borax-sand mixture.
Silica gel is commonly sold at florists, craft stores, and some hardware stores. It can be reused by drying it or baking it in a 200°C oven until it turns blue.
In a shallow, airtight plastic or glass container, spread the flowers you want to dry on a 1-inch-thick layer of silica. Carefully spoon more silica on top until the flowers are covered with at least an inch of powder.
Seal the container and leave it for 3-4 days. Do not leave the flowers in the desiccant for too long as they may become fragile and difficult to handle.
Another method is to microwave the flowers. Seal the flowers in a plastic container and microwave on medium-low power (about 350 watts) for 3 minutes. Allow the flowers to cool for at least 15 minutes.
5.) Finished flowers. Shake or brush off any crystals (if you used silica) and store the dried flowers out of direct sunlight to reduce leaching of color.
A wicker box with a lid or a similar container that allows air to circulate is ideal – never plastic. Even a cardboard box works fine as long as you cut a few holes in the sides and top.
Fragile flowers that split easily, such as larkspur, hydrangeas, and sweet Annies, can be made more durable with hairspray or a similar spray-on fixative (available at craft stores), which coats and strengthens the brittle stems and flowers.
If you're new to cut flowers or looking to expand the variety of flowers you have in your garden, Penn State Lancaster County Research Farm has found that 10 species are great for Pennsylvania gardens: annuals such as evening primrose, calendula, celosia, cosmos, dahlias, snapdragons, and zinnias, and perennials such as black-eyed Susan, yarrow, and Shasta daisy.
Other annuals worth trying for drying include ageratum, amaranth, rubber lavender, sunflower, strawflower, larkspur, marigolds, blue and red salvia, cleome, lisianthus, Mexican sunflower, nigella and osteospermum.
Other perennials suitable for cut flowers include purple coneflower, statice, gypsophila, perennial sunflower, heliopsis, mums, goldenrod, astilbe, goat's beard, carnation/dianthus, lavender, liatris, gaillardia, asters, salvia, poppies, agave, globe thistle, allium and sea holly.
Read George's post to learn how to grow your own cut flower bouquets. This variegated ground cover is called variegated bishop's weed, and it reverts to an invasive weed with green leaves called gauze weed.
A ground cover that has become a very troublesome weed
One classic example of a beautiful plant gone wrong is the ground cover known as variegated bishop's weed.
Introduced to the U.S. by European settlers in the 1800s, this shade-loving ground cover is still sold in some garden centers and is often passed down from gardener to gardener. (Divisions are easy to dig, divide and transplant.)
Bishop's weed is a favorite because of its bright white-edged leaves and because it grows easily in shady areas, in areas with deer, and even under large trees. It's sometimes nicknamed “mountain snow.”
The problem is that this attractive variegated plant can turn into a plain green-leafed plant (commonly known as “gout grass”) and overgrow in unwanted places.
“If you buy a variegated variety, it will grow back to its original color and be much more fertile,” says horticulturist Joyce Browning, Master Gardener coordinator for Harford County, Md., in a video on excellent knotweed from Maryland Extension's “Garden of Weedin'” series. “It's really a garden thief. Don't plant it.”
Bishop's weed grows to about 12 to 14 inches tall and has clusters of three leaves that alternate on the stem.
Browning said the plant's common name comes from the shape of its leaves, which someone centuries ago decided looked a bit like a bishop's hat.
Bishop's Weed/Goutweed plants send up flower stalks an additional 18-24 inches that produce flat, umbrella-like white flowers in June. The plant also spreads by small brown seeds that mature in late summer, but so far the primary way it spreads is by the plant's fast-creeping underground rhizomes.
When the colony greens up again, those rhizomes form dense colonies, apparently attempting to take over the earth.
Bishop's Weed/Gout Weed is feared to drown out native woodland species, particularly as it prefers moist shady to semi-shaded locations. However, it is not very picky about light, poor soil or soil pH and will thrive in unmanaged fields, roadsides and even in gardens with variegated Bishop's Weed.
Deer don't like knotweed, so it won't help control it in the wild.
This is a weed that is very difficult to control once established.
“It can take 20 years to pull it off by hand,” Browning says.
That's because goosefoot roots are good at growing new shoots from even the smallest bits left in the ground, and if you don't dig up and remove every last bit of the plant's root system, you could actually make the infestation worse, Browning warns.
If you want to avoid herbicides at all costs, digging, re-digging, and being vigilant and persistent is one option.
Another non-chemical option for sawtooth clumps is to cover areas of the clump with black plastic for at least a few months.
Otherwise, the Agriculture Extension Service recommends spraying hollyhock leaves with a nonselective herbicide such as glyphosate, which penetrates the roots and kills the entire plant, not just the above-ground parts.
According to the Pennsylvania Department of Conservation's fact sheet on carrot weeds, glyphosate is most effective when applied in the fall. (Gauze is on the DCNR's Pennsylvania list of invasive plants.)
Glyphosate can be used on goatweed where it grows among other desirable plants, and as long as the spray does not drift onto the leaves, the chemical will only kill the goatweed.
Overall, this will help avoid sharing transplants with neighboring plants and will help remove colonies of variegated plantain before it reverts to green plantain.
Tips on what to do and when: George's “Pennsylvania Gardening by Month” book
