Hot Weather Damages Plants

Our recent record breaking hot spell has caused a lot of plant damage. Plants “sweat” or transpire water to cool their leaves. The hotter the weather, the more water is pumped from the roots to the leaves. This extra need for water plus the increased evaporation dries soil very quickly. Even when extra irrigation is applied, sometimes plants cannot pump enough water to keep up with the needs of the foliage. This results in drooping and singed leaves. The newest leaves usually show brown edges and leaf tips the quickest. Sometimes whole branches drop their leaves. Most plants have enough food reserves to develop new leaves over a period of several weeks. So give them a chance to leaf out again before you cut off the branches. Some branches or plants may die completely. Fruits of tomatoes, apples and other fruits and vegetables have also been scorched where they were directly in the sun.

Insects and Diseases

Some insects and diseases are worse during hot weather. Insects multiply faster and some diseases grow faster during hot weather. Check your plants more frequently for holes and discolored leaves. Because most pesticides do not kill insect eggs, a followup application should be made about 2 weeks following the first application. By then most eggs have hatched but are not mature enough to produce more eggs. One of the best all round natural pesticides is Neem Oil, extracted from the Neem tree. It is effective against both insects and diseases. Neem is not very long lasting so application at one to two week intervals may be needed if you have a continuing problem like black spot on roses. Neem oil is usually only available at full service nurseries and garden stores. If you notice a plant problem, feel free to call or email me for advice. If necessary, I will come look at the problem, usually free of charge. I can also apply a variety of different pesticides.

Ornamental Grasses Becoming More Popular

The ornamental grasses come into their prime in mid-summer. Look around and you will see many different sizes and kinds. They are relatively easy to care for and have a lot of beauty in the fall and winter.

‘Karl Foerster’ feather reed grass (Calamagrostis acutifolia) is my favorite. Plants stand up straight as a soldier. They bend in heavy wind, but spring right back to their 5 foot upright position. Their feathery golden spikes reach full height by mid-summer. Feather reed grass makes an excellent background or specimen plant which continues to look attractive into the winter.

‘Skyracer’ moor grass (Molinia caerulea) is another variety which produces loose golden seed panicles early in the summer. ‘Skyracer’ grows almost 6 feet high. Leaves turn a golden yellow in October which adds to its beauty. A cousin of ‘Skyracer’ is the dwarfer ‘Variegata’ moor grass with green and yellow striped leaves. ‘Variegata’ grows only 3 feet high, but has the same loose golden seed panicles.

‘Bronze Veil’ tufted hair grass (Deschampsia caespitosa) has one foot tufted green clumps of grass that are topped by loose, hair-like panicles about 3 feet in height. The bronzy-colored seed heads last from mid-summer into the winter.

There are a number of varieties of maiden grass (Miscanthus sinensis). Plants grow 5 feet high or taller during the summer. Then in September they produce spectacular silver flowers resembling hands with fingers. ‘Variegatus’ has gold stripes the length of the leaves. Porcupine grass has broad yellow stripes across the wide leaves. ‘Purpurascens’ has purple and gold leaves which are especially bright in the fall.

Fountain grass, (Pennisetum alopecuroides) produces 3 foot fountain shaped plants topped by purplish-pink fox tail flowers in late summer and fall. Variety ‘Hameln’ has the same form but grows only 2 feet tall. ‘Little Bunny’ grows a foot high. There are purple leaf varieties available also.

I googled “ornamental grasses” and found many pages of references. The university sites were the best. The one from Colorado State University had some of the best information and pictures. (www.ext.colostate.edu/pubs/garden/07232.html). You can also google individual grass variety names.

Respect Trees

To me trees are the ultimate symbol of nature in all its glory. They are the single most important elements in landscaping. I am reminded of the song lyric “Did you ever hear a poem as lovely as a tree”.

In recent years, large trees have been salvaged and moved to new locations, rather than bulldozing or cutting them down. New equipment is able to dig and move larger and larger trees. I know of one landscape contractor in California who uses a helicopter to move trees which are 50 feet and more in height and breadth.

Sometimes we take trees for granted. They seem to survive and grow when we just ignore them. They get water and nutrients when we feed or water the lawn or other plants nearby. If a branch dies or breaks off, we may cut it off. If branches grow in the way where we walk or drive, we hack them off. If branches grow where we are mowing the grass, we get irritated and remove them. When large trees get planted under utility lines, they get pruned repeatedly so they will not disrupt the power supply.

I frequently see large trees which have been topped when there is no apparent reason. When I ask why, the reply is simply, “they were getting too big”. There are sometimes good reasons for shortening or removing a tree which is in danger of damaging buildings in a storm. However, unless a 50 foot tree is too close to a structure, there is no need to butcher it to a smaller size. Most trees which naturally grow that large have the structural elements necessary to succeed. In fact topping them simply stimulates them to grow many structurally weak branches to replace the few strong branches. The tree grows back to its original height within two years, but much weaker than before.

Vancouver and many other cities have ordinances against tree topping and removal. A permit from the City Forester is needed for trimming or removal near streets.

Tree branches which are growing where they are dangerous can be removed entirely or shortened back to a side branch which is at least 1/3 the diameter of the branch removed. This results in much less sprouting of weak, upright branches.

If you have a tree which is outgrowing the space where it was planted, why not hire a professional to move it to a new location where it has enough room to grow? Or if you no longer have room for it in your landscape, perhaps it can be moved so someone else can enjoy it.

If you have a tree which is difficult to mow under, why not eliminate the grass instead of the lower branches? One treatment a year with Casoron will keep the grass and weeds from growing under a tree. And without that competition for water and nutrients, the tree will grow faster and be healthier.

Remember, it takes a long time to grow a large tree. Don’t shorten the life of a beautiful tree by ignoring or mistreating it.