It is nearly warm enough now for northern growers to move tender plants out into the greenhouse and look forward to cucumbers, peppers and ripe tomatoes. But anyone who has had a lot of potted plants to tend through a summer knows that watering can be a bit of a chore, especially when plants like tomatoes get big and thirsty. Drip irrigation systems work really well with Air-Pot containers, if you can raise a barrel or tank near your potted plants the drippers can be gravity fed and controlled by a battery powered timer.
This is convenient if you do not have a mains water supply or just do not want to trail high pressure pipes around your garden. A large tank on a 60cm high platform beside my greenhouse feeds 20 or 30 pots for 10 – 14 days which is truly liberating. If you are setting up this type of low pressure system it is important to get the correct type of timer, many use a diaphragm valve which can only open if water pushes through at mains pressure. But the cheaper simple designs have a ball valve which opens and closes as the ball turns through 90 degrees, the type with a clear circular screw cover costs about £15 and is sold under several brand names including Kingfisher. The timer screws directly onto the thread of a garden tap and it is worth fixing this type of tap to a stake right in your greenhouse. It is then a fairly simple plumbing job to run some flexible plastic 15mm (1/2 inch) pipe between your tank and the tap. Most dripper systems will then connect to the standard garden hose click connection at the outflow end of the timer.
Usually a short length of 15mm garden hose acts as a manifold with several lines of the small diameter irrigation pipe running from puncture connections into the rubber hose. After a bit of adjustment of the drip rates it should then be possible to leave your plants for as long as the reservoir lasts.
We are expecting a mid-May cold snap here in the U.K. so my potatoes at the plot have had earth mounded up over the young shoots to protect them, but the early planted Air-Pot potato tower already has big plants about to flower, luckily the clear bubble plastic stills fits around the pot and plants. With a bit of fleece on top this should mean the extra-early crop stays snug.
Two cherry trees which had tiny root balls when I bought them two years ago have established well in their Air-Pot containers and have blossomed for the first time this year. Commercial growers do get good crops from container grown cherry trees so it will be exciting to see how these do.
The “Kordia” variety can grow several metres tall so may outgrow even the biggest pot but the smaller growing “Van” is meant to be well suited to container growing.
The container carrot experiment continues, the carrots in the 50 litre Air-Pot look to be appreciating the deep soil, and two little “Long Tom” pots we made from Air-Pot wall material offcuts are bravely thrusting down in their bespoke deep pots.
Two other plantings which are just bursting with heathy growth are my favourite variegated hosta grown from a small offset and a tray thickly planted with Spring Onions which will provide welcome early season greenery.