Q: Should I be cutting back on watering my plants, now that the growing season is ending? I think that is supposed to harden them, so that they will survive the winter. I am particularly interested in a plum tree. Half of it died during a bad winter, but this year the other half has a wonderful crop of plums. I don't want to lose it.
A: This question does not have a one-size-fits-all answer. Annual flowers and vegetables that are actively growing still need water. Those that are finishing their season need little or no water now. Perennials, trees, grass, and shrubs still need water.
Nothing needs to be irrigated as much as in the hot weather of July, though. Afternoon temperatures are lower; if the air is smoky, they are much lower. Night temperatures are not much colder, but the cold lasts longer because the nights are appreciably longer.
Trees are a separate matter. Eventually you may want to cut back on watering all your trees, not just the plum, but the time for that has not arrived. Your plum tree is still ripening fruit. There is disagreement among horticulturists about the benefits of having trees get used to less water before their tissues freeze. Trees soon will be manufacturing antifreeze, which will prevent their cell walls from being destroyed by ice crystals. It is important that they have enough water to make the antifreeze.
The cold hardiness program, which trees carry out, actually has two parts. Sugars in the sap increase. As the liquid sap becomes more sugary, it freezes at a lower temperature, perhaps five degrees lower. At the same time, tree sap can be supercooled. This process is triggered when temperatures drop below 40 degrees for several nights in a row. Supercooled sap has no particles or air bubbles. These would have made nuclei for ice crystals in cold weather. Without them, ice crystals do not form, and the trees can survive temperatures as low as -40 degrees. A few kinds of trees can remove water from their cells and move it to the spaces between cells, where freezing will not break the cell walls.
The tree experts who recommend less water in fall believe that decreased water helps trees understand that winter is coming. Since most trees in our gardens, including your plum, are not Montana natives, they may not be accustomed to our weather patterns. A tree should not be growing new leaves now; it should be maturing the leaves that already exist. If a tree is growing new leaves, decreasing its water supply may help to change its growing pattern. However, some trees, both fruit and ornamental , are adapted to a much longer growing season than ours. Nothing will help them adjust to Montana's yearly cycle.
If you opt for less water to "harden" a tree, be cautious. Changes should be moderate and gradual. Be sure that irrigation is enough to penetrate deeply into the soil, not wetting just the top few inches. Keep in mind that drought is a common cause of trees dying in winter. Have you noticed any public plantings of young trees that have dead limbs, especially on the tops? That is the result of going into winter in dry soil. Be sure that all your trees are in damp soil just before freeze-up. After deciduous trees drop their leaves, and before Christmas, water generously one more time in all the dry places. This final watering may be unnecessary in years with good fall rains. It is critical to tree survival in years with low fall precipitation.
Q: Can I grow apple trees from the seeds in my apples?
A: Yes, you can, but only rarely does someone try. Seedling apple trees are not like the parent tree, and most seedlings have undesirable characteristics. Good new apple varieties can appear from chance seedlings, but their number is eclipsed by the myriad of seedling trees producing fruit that no one wants. Since apple trees are notoriously difficult to grow from cuttings, most are grafted.
Q: When I dug my carrots, I discovered that several of them had branched underground. What can I do to avoid that next year?
A: Perhaps you can solve the problem in all your carrots. Depending upon your soil, perhaps you can solve it only in some of them. Carrots will subdivide if their soil is compacted. If it contains rocks or pebbles, the carrot tip will try to grow around even a small stone. Usually the carrot splits and tries to grow around the stone in both directions. If you have no pebble-free soil, you may have to accept that a few carrot tips will touch rocks as they grow downward.
If most of your carrots branched, or if the soil has no rocks, the problem may originate in their cultivation. Carrots will divide into prongs if they are transplanted. Their roots, especially the growing tips, do not like to be touched or disturbed. Carrots also will fork if they have grown too far before they are thinned. Also, the roots will divide if they are touched at any time by careless weeding or hoeing. Treat them always as the most delicate vegetable in the garden.
To grow carrots with the best shape, thin the plants to about three inches apart when they are no more than three inches tall. For the rest of the growing season, be gentle as you clean out the weeds. And, of course, plant next year's carrots in the part of the garden with the fewest rocks.
If you want to grow the perfect carrot, guaranteed to win the blue ribbon at the county fair, here is the established technique. It is only for devoted carrot growers. Punch some holes in a five-gallon bucket. Fill it with coarse sand and moisten the sand. With a crowbar, bore a hole for each carrot. Do not try to grow more than six carrots per bucket. Fill the holes with a mixture of potting soil and compost, in equal parts. Add a little fertilizer to each hole. Sow carrot seed on the top of each hole and care for the carrots as usual. They can be harvested by turning the bucket on its side and pouring out the contents.
RED PONTIAC POTATOES
My vegetable discovery of the year is a potato variety I had not tried before, Red Pontiac. Even in this year of uncooperative gardening weather, the plants produced a respectable number of perfectly-sized potatoes. There were no marbles and no monsters. And no scab.
Intrigued by the uniform size and shape, I researched something of the varietal history. Many other gardeners like this potato, which seems to adapt to a huge variety of growing conditions. A widespread crop in this country, it is also popular in South American and Australia.
Red Pontiac turns out to be an old variety which first appeared on a plant in Florida in 1945, as a mutant of a still older variety called Pontiac. It is good for most potato cooking methods. This is a potato that I will be growing again.