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.

Many people are spending time at home and experiencing difficulties getting supplies from the shops at the moment so it is especially worthwhile having some way to grow your own. A couple of pots planted with Spring bulbs can really lift the spirits, tulips and grape hyacinths have provided a succession of long-lasting colour which have occupied a prime spot by the front door when at their best.

The experimental extra early planting of potatoes appears to be successful, the shoots are showing above the soil in the Air-Pot potato tower, these plants should crop a month or so before any planted in the ground. Despite some frosty mornings the shoots are undamaged protected by the wrap of heavy duty horticultural bubble plastic which creates a mini poly tunnel around the pot.

About the fastest pickings from a Spring sowing of any crop are rocket and radish, these do well in an Air-Pot tray in a greenhouse where they crop sooner and stay in much better condition than when sown on the plot. A sowing of rocket made a couple of weeks ago should yield some leaves in another week and continue to produce into summer; this variety named “Speedy” has lived up to its name.
One of the foods which for many is a real store cupboard staple is tinned tomatoes, a way to get the equivalent of crates of tinned toms is to grow your own and bottle or freeze them. Tomato seeds can be sown now, after comparing growing in bags, in the greenhouse soil and in conventional pots, Air-Pot containers have proved to be the best for me. The taste of these bottles of sunshine is fantastic and so useful in soups, sauces, and on pizza and pasta.

Various members of the onion family are putting on nice clean growth now, a pot of chives has awoken after its winter dormancy. It has been happy in this large pot for years now only needing an annual top-up of compost and the occasional feed. Small pots planted with Elephant Garlic and French Potato Onions (similar to shallots) have been given a good start in 1 litre prop. pots. These will be planted in the ground soon and should be ready to lift soon after mid-summer.
Finally a sedum / Ice Plant which is commonly grown as an ornamental has produced some fresh new growth, surprisingly these are edible and are especially crunchy and succulent in salad now when leaves are young.

Northern gardeners will be seeing signs of growth now that the winter is nearly over. With some forward planning the Air-Pot containers which were full of summer crops all those months ago can be useful during this quiet time .

I have some iris, tulips and muscari bulbs coming to life which  will give some colour, and little Walking Onions which will be good for salads. These onions (a.k.a. Egytptian or Tree Onions)  produce small bulblets similar to little onion sets high on the flower stalk. These can be planted in the Autumn to provide a big pot full of Spring green onions. Elephant Garlic is another edible bulb which I have in Air-Pot containers. The 1 litre Prop Pots are perfect to get them off to a good start prior to planting out on the plot as the roots do not get congested, as they do in a conventional pot.

Christmas trees in pots stand a good chance of surviving until next festive season if they are well watered. Surprisingly conifer roots are actively growing now and many Christmas Trees sold in pots have had their roots hacked about, so watering and feeding will be crucial until they have recovered. My tree is now in an Extra Large Air-Pot and has been our Christmas companion for four years.
Potatoes can be planted now if you are prepared to protect shoots from frost. Three tubers in a 50 litre Air-Pot Potato Tower can produce several kilograms of extra early potatoes in a greenhouse. This year as an experiment one Potato Tower has been wrapped with sturdy bubble wrap to create an individual mini greenhouse and to ward off hard frosts which might penetrate the soil.

The tomatoes and peppers have all done well in Air-Pot containers but are now nearly all finished. Maskotka is an early ripening sprawling type of cherry tomato which looked good on the patio as well as providing good eating.

The yellow piripiri was the most productive of the chilli varieties, it is an accidental cross between a red piripiri and some unknown father.

A batch of hot sauce made from a mix of peppers and chillies has just gone into bottles and is tasting good. This sauce is a Sriracha style, which means it was fermented with lots of garlic, and the heat is down to family friendly levels; a warming condiment for the winter ahead.

Raspberry plants do not generally grow well in pots long term, but some Autumn fruiting canes which are temporarily in an Air-Pot container have provided quite a few bonus berries. It might even be possible to keep them fruiting for longer by moving into the greenhouse. Now the tomatoes are cleared out there are a few things which might extend their cropping season by coming under cover.

Colder weather is threatening some of the more tender plants such as the lemon grass, which was grown from seed this year. It has formed a good clump in an Air-Pot and is big enough to provide some leaves for flavouring curries. To get the tender inner stems which are the most flavoursome it needs to continue growing into next year. So the pot will be moved into frost-free quarters for the winter.

A pot full of Garlic Chives is dividing and flowering well after being rescued from an overgrown veg patch. Most alliums seem to thrive in the free draining conditions provided by an Air-Pot. Garlic Chives can actually bulk up to the size of baby leeks when they are happy, so potentially they can be more than just a garnish, and be used in stir-fries or as a filling for dumplings.

As the season is well advanced now it is satisfying to see good growth on plants which were potted-on into generous sized Air-Pot containers earlier this year. Two plants I wanted for their striking foliage are well on the way to becoming dramatic specimens. An Agave filamentosa has formed a neat rosette of variegated spears and a Phormium is developing an interesting stripy bronze fan, both of these will be exciting shapes and colours to have around the garden, especially in winter when there is little leafiness or colour.

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A little collection of potted Canna Lily have all thrown up dense thickets of stems; moving them into bigger pots has resulted in vigorous multiplying shoots and lots of blooms. Usually Canna are grown from rhizomes, but a few seed saved last year and sown in February have formed many shoots and surprisingly have flowered after just a few months.

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A young olive tree started in a 1 litre Air-Pot has doubled in size since being moved into a 3 litre earlier this year and has a good sturdy shape with dark green healthy looking leaves. Another much older olive tree recently moved into an Extra-Large 38 litre Air-Pot has produced a huge number of flowers for a container grown tree. This veteran plant seems determined to produce olives this year but I fear it will soon run out of summer, so ripe olives are unlikely. Good to see it attempting to procreate though.

Another tree trying to fruit is a citrus called Yuzu, apparently this is grown in Japan where winters can be cold so perhaps ripe fruit in Scotland is possible.

A late sowing of New Zealand Spinach produced little plants which were set in a large Air-Pot in late July. By late August the plants had filled the pot and provided enough greenery for a good amount of spinach and made a paneer curry. It is continuing to grow fast and a week later is ready to pick again. This is a tender plant so it will be interesting to see how well it can grow into the cooler end of the season.

July and August is when lots of the crops in pots start to yield good pickings. The thing I am most excited about is the amount of carrots produced in one 20 litre Air-Pot (3.2kg / 7lb). The seed was sown in Spring in a shed, which meant the soil temperature was  warmer and drier;  once past the early vulnerable stage the pot was left outside and well watered. I did not even thin the seedlings which would have given each root room to grow bigger. They seemed to reach a useful size despite the overcrowding and best of all the carrots were absolutely perfect with no carrot root fly damage or forked roots. I have immediately followed this success with a late sowing and in future will aim for a succession of carrot pots.

The runner beans in a pot are looking good and producing pods. Many beanstalks can grow huge and require substantial supports, which is awkward in a pot and liable to blow over, so I selected a dwarf variety named Hestia which has been very well behaved reaching only 60cm in height. About a dozen plants in a large Air-Pot with a few sticks for support have been covered in pretty red and white flowers for weeks and will now give plenty of beans for the kitchen. It is easy to end up with a glut of runners and as they are not something I love enough to freeze  it is quite a relief to just have a potful rather than a wigwam load.

There is so much fresh growth on the Air-Pot herbs I thought it would be good to preserve some as a herb salt, I gathered a big bowlful of mixed herbs; oregano, chives, sage, rosemary, lovage, tarragon plus some chilli, celery, lemon zest, spring onion, seaweed and garlic granules. This was all dried, ground and blended with salt to make a tasty flavour enhancer.

Once again the hydrangeas on the doorstep are a mass of pink, they are several years old and are now thriving in the 20 litre size Air-Pot. They could be potted-on into the 38 litre extra large size but they then become rather heavy to move, It is nice being able to easily shift the pots into a prominent position when they are at their best, I find the 20 litre (large) is most useful when juggling pots, the 38 litre (extra large) good as a final home. Sometimes you have to concede that a plant is just too big to contain, my banana plant grew so quickly in a series of Air-Pot containers that eventually it outgrew the extra large size and was planted outdoors in the ground, it is now over 3 metres tall and has survived a Scottish winter.

The Air-Pot garden is growing fast now we have long days and warmer temperatures. The mange tout pea Shiraz have proved to be well suited to container growing. They were easy to keep neatly trained onto their tipi and stayed at a manageable height of about 1 metre. Next I am going to try Sugar Snap peas.

The mixed pot of spinach and kale provided a long period of useful greens and was pretty enough to have prominently on display, the Red Russian kale variety has very ornamental frilly leaves. These good looking kales are something to sow now to plant out at the end of summer as they are hardy enough to grow on into the winter.

There has been lots of potting-on to do of various perennial plants which are going to stay in containers long term. Some plants which do not need moving into bigger pots quite yet still need a bit of attention. Compost levels  settle over time in any container and it is well worth taking the opportunity to top-dress. I remove any moss and mould from the surface and press down firmly around the edge, this makes space for about 5cm of fresh compost and a sprinkling of chicken manure pellets.

    Before and after of a small apple tree that I grew from a pip. The second picture shows the top-dressed pot with the Air-Pot container correctly filled to near the rim.

The Bulgarian Giant leeks which were sown thinly directly into an Air-Pot in winter have now been planted out on the plot, they were considerably fatter than the grass-like scraps I have planted some years.

The greenhouse cucumber plants have gone into their final pots, I have one in a 20 litre and another in a 9 litre just to see how this affects yield and growth. I am trying the variety Carmen this year after seeing that it wins most of the top prizes at vegetable growing contests.