Newly planted trees have very poor root systems and you need to use a tree-root watering system to get the water down to their roots.
Your trees are the most expensive component of your garden's planting scheme. Apart from the expense of replacing trees that have died they are very slow to grow. If a tree dies from a lack of water it will take years to regrow a new tree to the same size as the old one.
You can buy superb systems designed to water your trees' roots. Some of these incorporate a water reservoir, others have ready designed stoppers for the tubes in the ground. Some have an augur on the bottom of the ground tubes and a capstan arrangement at the top. This will make it much easier to insert the watering tubes and removes the need to hire a post borer.
You can use any tree-root watering system to deliver fertilizer to a tree's roots. Slow release fertilizers such as sea weed or blood fish and bone are best for trees and if you just sprinkle these on the ground you will find they attract rats, deer and mice. Throwing a trowel full down your each watering tube is a very convenient way to make sure your trees get the nutrients and not your local rats.
tree-root Watering – Why is it Necessary?
Cheap bare root trees have only a tiny fraction of the root system they had before they were dug up. These trees are cheap because transport costs are much less than for much heavier and more bulky container grown trees.
Trees absorb water through the millions of fine roots they have. When bare root trees are dug up, 90% of the trees' roots, including 99% of the fine, water absorbing roots are left behind in the soil.
If you plant these trees in fall, then the roots start to grow as the soil warms up in spring, but it will take up to five years before the trees' roots are fully developed.
If you buy root-balled trees the situation is slightly better, but they still only have half of the water absorbing roots they need, and none of the deep roots.
Container grown trees have all of their roots, but a tree that is ten feet tall, should have roots three or four feet deep, not the foot deep roots that the container limits them to.
All newly planted trees therefore need their roots watering, especially bare root trees.
If you water the ground's surface around a tree it has several undesirable effects; the ground becomes swampy, the roots are encouraged to grow nearer the surface, the tree dies because you cannot give it all the water it needs from the surface.
tree-root Watering – How Do You Do It?
For each tree cut four 3 foot lengths of 3 or 4 inch PVC drain pipe. Drill holes at 3 inch intervals all the way up the pipe. You can use an ordinary wood-bit for this. The size of the holes does not matter.
Block up the bottom of the pipe with some inert material, plastic egg boxes are ideal. This stops soil slowly clogging up your pipe.
You need to sink this pipe into the soil. The easiest way is to use a post borer, you can hire powered ones, or you can do it the hard way. If the tree is surrounded by grass then ensure that the top of the pipe is flush with the soil. Put something in the top of the pipe to stop children throwing toys down it and to stop it becoming clogged up with grass cuttings over time.
If your trees are away from any grassed areas then leave the top of the pipe proud of the soil by two inches. You still need to block the top, because of the fascination that all children have with dropping things down holes.
The degree of ingenuity required will depend on how persistent your children are. You may be able to get away with crumpled black bin bags, or, at the other extreme, youmight need tapered wooden stoppers that are bolted and padlocked into place.
tree-root Watering – Where Do You Do It?
A tree's roots should stretch out below ground as far as the branches do above ground. This is sometimes called the Drip Area.
Sink your PVC tree-root watering pipes just outside the current Drip Area. As the tree grows its roots will extend further, but by that time its roots will be well enough established and you will not need to worry about watering the roots.
tree-root Watering – When Do You Do It
Once a month, through the summer with any trees you have planted within the past five years. Pour Water down each root-watering pipe until the ground under your feet feels wet. Repeat for each pipe in turn.
tree-root Watering – How Long Do You Have to Do it For?
For at least the first three years after you have planted the tree. The roots will barely grow in the first year, but their outward spread will accelerate year by year.
Leave the tree-root watering system in place, even after five years, in case you have three months of drought in ten years time.
Adapting the tree-root Watering System for Shrubs
Shrubs, especially bare root specimens have a similarly poor root system, though they do usually have more fine, water absorbing roots remaining than trees do. You can use a similar system to keep your shrubs healthy in summer.
Use shorter lengths of pipe; 15-18 inches will suffice. Only water in extreme conditions, though, as drought will naturally force shrubs to send their roots deeper into the ground to find any remaining water. You need to encourage this deep rooting tendency and watering before the plant I showing signs of distress will discourage it.
When you dig a hole to plant any shrub leave a length of drilled drainpipe sticking out of the hole. This gives you a convenient way to get water down to the shrub's roots if you ever need it.