This has been an unusual year to say the least, and the summer seems to fall right in line with being unlike the last few summers weather-wise. After at least three years of abundant rainfall and fewer 90 degree days, this summer is turning out to be very hot and dry. After a brief respite from the heat and a nice soaking rain in mid-July we are on track to go back to the 90s with the only rain coming from sudden and intense storms. Hopefully August will be a little kinder to us, but I am not planning on it. Here are a few hot weather gardening tips in case the trend continues.
- Watering is the most important. Water in the mornings so the moisture has a chance to soak in before evaporating in the heat of the day. Water the base of the plants and the soil; even if the plants fade in the heat of the day, as long as they can take up moisture through their roots they will perk up when it cools. Container plants may need to be watered every day as the soil in them will dry much faster than the ground. Try not to use overhead sprinklers as most of that water will evaporate or blow away before it hits the ground. And avoid getting leaves wet as that can lead to leaf burn or foliar disease. Inconsistent watering can lead to some problems in vegetables, including blossom end rot in tomatoes, peppers and zucchini, and hollow heart in potatoes and boron deficiencies in cauliflower and beets.
- Don’t use herbicides or pesticides. The heat can cause them to become volatile (turn to gas) and cause damage to unintended targets. Always follow label directions when using herbicides and pesticides, including recommended temperatures for use.
- Deadhead your flowering plants. Once pollinated flowers die, the plant puts most of its energy into producing seeds. By cutting off the dead flowers the plant will use its energy to produce more stems and leaves and store its excess in the roots. In perennials that will ensure that they will survive the winter and come back strong next year. Annuals, frustrated by their efforts to procreate (make seeds), will usually produce more flowers the rest of the season. Some perennials may even reward you with another bloom–I know my roses do, although the second bloom is not as prolific as the first bloom.
- Mow your lawn less often. Most of our lawns are cool weather grasses that go dormant in very hot weather, so they will not grow as fast any way. If you do mow make sure you do not mow shorter than three inches. Then the blades can shade the crowns of the grass from the intense heat. Your dormant lawn may look brown but that doesn’t necessarily mean it is dead. Cooler weather will most likely see it return to green and growing. Do not fertilize your lawn in hot weather — that will encourage growth and thus stress the grass plants. If you choose to water – see the info above.
Some common problems seen by gardeners in this weather are sunscald and wind burn on plant leaves, reducing their ability to photosynthesize. We are also seeing fewer diseases but more insects such as potato beetles and cucumber beetles. Aphids and leaf hoppers that don’t normally appear till mid to late July have arrived much earlier, apparently blown in by
Tropical Storm Cristobal in early June. And last but not least, a new invasive insect pest has turned up in Minnesota!
A gardener in St. Paul has reported, and the Minnesota Department of Agriculture has confirmed, the appearance of the invasive Leaf Lilly Beetle. The beetle is a 1/4” insect, bright red with black head, antennae and legs. The adult beetle is active from May through September, feeding on the leaves of true lilies (Lilium spp), which includes Asiatic and Oriental lilies, Fritillaries (Fritillaria spp), Lily of the Valley and Solomon’s seal. They do not bother daylilies (Hemerocallis spp), Canna Lilies (Canna spp) or Calla Lilies (Calla palustris). They chew on the leaves, stems, flower buds and flowers causing severe damage, and can completely defoliate plants leading to their demise. The beetle is common in Europe and Asia and was first discovered in North America in bulbs in Montreal in 1945. It was found in Massachusetts in 1992 and has been making its way to the Midwest. It is now present in 15 states including Wisconsin, Iowa and now Minnesota. The Minnesota Department of Agriculture is attempting to track this invasion and asks that anyone who finds one report it to them at arrest.the.pest@state,mn.us or 1-888-545-6684.
Yes, 2020 has been an unprecedented year, but let’s keep on gardening!