Preventing overwintering pests and diseases in the greenhouse.

Saturday turned out to be a nice day weatherwise here. The sun shone brightly and the greenhouse suddenly warmed up, so, looking forward to spring, I decided to get rid of any pests and diseases which  may have overwintered in the greenhouse, by burning a sulpher candle.

This is not very organic, but I don’t profess to garden totally chemical free. I just try to use as few chemicals as possible and look for alternatives if possible. I always look carefully before smoking the greenhouse to see if there are any beneficial insects which I do not want to kill. Plants which have been stored in the greenhouse do not seem to suffer from the treatment.

There are a number of pests and diseases which can populate your greenhouse without you being aware of them until they become a problem in spring and summer. Some overwinter in the greenhouse, so it is worth treating the greenhouse to rid yourself of the worst of them before you start a new year. Remember though, this treatment is indiscriminate and will kill beneficial insects as well as harmful ones.

Pests and diseases in the greenhouse can build up rapidly because of the warmth and humidity. It is always best to keep a careful watch for them and try to prevent them building up. Always maintain scrupulous cleanliness and remove any damaged parts of the plant as soon as you spot a problem. Do not compost that plant material – burn it.

There are a number of fungal diseases which affect your greenhouse plants and one of the worse, in my opinion , is damping off. This shows as a blackened area at the base of the stem and in very short order the affected plant will topple over and die. There’s nothing worse than sowing and nurturing a plant only for it to suddenly die. There are a number of things you can do to prevent it (there is no cure). First, sow your seeds more thinly, water less and increase the temperature in the greenhouse. Sometimes, the disease is carried in the soil and if this is the case you will need to sterilize it by heating it to kill it. Watering other plants with copper fungicide will help prevent itspreading.

Red Spider mite are almost invisible to the naked eye and you don’t see them until there are loads of them. They are green as well as red and they cover the plants with webs and cause fine mottling on the leaves. They are only a problem in a dry atmosphere so increase the humidity to safeguard. There is a parasitic mite which will control it, but if you have a small infestation you can spray with derris

Whiteflies are another serious and persistent greenhouse pest. They are small white flies (as the name suggests) which weaken the plants by sucking sap. They are often found on the undersides of leaves. They can be controlled by a parasitic wasp. Alternately hang a grease coated yellow card in the greenhouse. For some reason, many insects are attracted to yellow and they stick to it. If all else fails, spray with derris three times at five day intervals. Do not spray if you have already introduced biological control.

Rock Gardens and Rockeries

Purists will tell you that there is a difference between rockeries and rock gardens. They will even look down their noses at rockeries. Ignore them!

The difference between rockeries and rock gardens is mainly scale and the emphasis of rock or plants. In rock gardens, the rocks are very large and that is the main thrust of the installation. Plants are usually quite small and widely spread, put there to stress the size and shape of the rocks.

Rockeries, however, are often small parts of normal size gatrdens, often built next to, or around small ponds and their space is shared with specially chosen plants.

When building a rockery, chose your rocks with care. Place them so that they look as if they were meant to be in the ground there. They need the bottoms covered with soil, so that they, as well as your plants, have grown there. Leave room between your rocks for your plants to expand but not too much room. You don’t really want bare soil between the rocks.

Plants for rockeries are great. You can get so many shapes and colours in a small space. There is a huge selection to choose from, some are only suitable for a position in the rockery whilst others can be used in other parts of the garden.There are even rock versions of much larger plants. Often rock plants are ones which will spread rapidly and rampantly, so the positioning of them is important so that they are contained.

Salix Apoda is a small plant, only 6 inches (15cm) high with a spread of 12-24 inches (30 -6-cm). It is, in effect, a miniture willow. It is a slow growing a deciduous shrub. In early spring male forms bear fat, silky silver catkins with orange to pale yellow stamens and bracts. The leaves are oval and leathery. When they are young they are hairy and become dark green later.

Sedums and  Saxifraga are large families  of plants which are recognisably related and they have varieties which provide interest throughout the year. You could build a rockery using only those plants and it would still be attractive. Check out saxifraga burseriana which have large white open cup flowers in the early spring. It is evergreen, so will look good throughout the winter. Saxifrage ‘hindhead seedling’  is another evergreen but has a hard dome of small spiny blue-green leaves. It has open upward facing pale yellow flowers in spring, whilst saxifrage sancia has tufts of bright green leaves all year with short racemes of upward facing bright yellow flowers in spring.

In summer, the sedums take over, with sedum acre being the most common. ‘Aureum’ is a variety which is evergreen, dense and mat-forming with spreading shots, yellow tipped in the spring and early summer and clothed in tiny fleshy, yellow leaves. It bears flat heads of tiny bright yellow flowers in summer, hence its name. Less well known,but equally showy is seduym lydium. This has reddish stems and narrow, flesht often red-flushed leaves and bears flat topped terminal clusters of tiny white flowers in summer.

There are so many different plants you can choose from for rock garden, it bogales the mind. Check out the Gentians, the campanulas, geraniums and the dianthus families. The thyme family also provides great miniature plants.

The great thing about having a rockery in your garden is that in a quite small space you can have a rich variety of plants which you wouldn’t have room for if you grew varieties in any other positi0n. So ignore the rock garden snobs, go for it and enjoy!

Green Manure Crops

Green Manure crops are crops which are sown and grown on land which is laying fallow with the express purpose of digging them in so that they will improve your soil. There are two very different types of green manure – those which fix nitrogen inthe the soil and those which do not do so. The one you choose will depend mainly on the nature of your soil and the length of time you are going to leave it to grow.

Green manure plants that act as nitrogen fixers include: Alfalfa (Lucerne); Broad or fava beans; Red clover; Lupin and winter tare. Green Manures which do not fix nitrogen include: Buckwheat; Rye; Phacelia; Mustard and Italian Ryegrass.

Italian Ryegrass is a particularly useful plamt as you can sow it early in the spring and it will quickly germinate even in cold soil. It is fast-growing and bulky. So you can sow it very early and dig it in before the ground has warmed up sufficiently to plant out tender vegetables. Be careful though, you must ensure you use the annual strain called “Westerwolds” and not the biennial or perennial ryegrass. You must also be sure to dig it in before it produces seed.If you sow the wrong type of rye grass, you will never get rid of it.It will keep regrowing no matter how many times you dig it out. The latin name for Italian ryegrass is Lolium multiflorum.

Phacelia (Latins name:Phacelia tanacetifolia) is one of the best green manure crops in spite of the fact that it does not fix nitrogen. It does not rob the soil of nutrogen either. It does not withstand cold, so sow it after the threat of frost has passed and dig in after about eight weeks.

Buckwheat  is useful only where you have space available for the whole of the summer (most of us haven’t) Sow when it is warm in the spring or early summer and dig it in in autumn. Buckwheat is tall and has a very extensive rot system. It makes loads of organic matter but does not fix nitrogen. To add to its advantage: it attracts hoverflies which eat greenfly by the thousand.

Mustard is very useful since it is very quick growing and is a good weed supressor. It is shallow roted so is easy to dig in. Sow in spring or summer and dig in autumn before it flowers. The snag with mustard is that it is a member of the cabbage family so it could harbour club root.

Broad or fava beans is a really super green manure crop. It will stand the winter weather almost everywhere. It produces loads of organic matter and fixes nitrogen. Sow in autumn or early summer, harvest the beans then dig the rest of the plant in.

Lupin is a deep rooted legume which adds nitrogen and large amounts of phospherous to the soil. Sow in spring and cut down and dig in in summer.

Red clover has an extensive rot system that will supply plenty of organic matter. It is low growing and a good nitrogen fixer, It is best to sow it in spring or early summer but always before autumn. Dig in when the land is needed.

Useful Weeds

Most gardeners ruthlessly remove all weeds as soon as they see them. They are often unsightly, compete with our  cultivated plants for nutrients and water and can harbour pests and diseases. However, some weeds are beneficial, and perhaps you could find a small part of the garden to allow them to grow.

Dandelions are rich in minerals. The young leaves are good to eat in salads and the roots can be used to make a cafeine free coffee. Of course pet rabbits (and wild ones!) and hamsters love the flavour of dandelion leaves as well. They also attract butterflies and bullfinches. Many years ago, Blue Peter cultivated a lawn of Dandeli0ns and whilst I would not adbvocate going that far, a few somewhere in the garden might be useful.

Some weeds can be very attractive, Herb Robert, Poppy and Red Campion come under this catogary. Herb Robert seeds and colonizes very quickly even in poor soils so it gives cover to pest predators and after it dies down (it is an annual) it will provide organic matter, so improving your soil.Be warned, though, you need to keep it under control or it will be everywhere. Red Campion attracts bees which pollinate flowers and butterflies and moths – drawn by the perfume released by the plant at night Butterflies and moths (and their caterpillers) in turn will attract birds. Red Campion is a Lychnis and when cultivated the size of the flowers will increase. Everybody knows the wild red poppy. Butterflies and bees are attracted to the flowers and birds are drawn to the seeds.

Nettles are not all bad. They are an important food source for butterflies. The young leaves can be boiled and eaten as a spinach substutute. Don’t leave them in the ground too long though, their roots get very thick and become very difficult to remove. They spread through their roots, so need to be kept severely under control.

Teasels are an outstanding biennial weed which are often cultivated in the ornamental garden for their striking seed heads. Birds are attracted to the seeds in autumn and the seed heads make great Christmas decorations.

These are only a few of the useful weeds in our gardens. There are a number of others. So before you eradicate all the weeds, think about how much harm they are doing and whether you could benefit from leaving them, or growing them elsewhere in your garden (under hedges are often a good place, since they are less noticable and will be less rampant there.

Seeds to sow in February.

If, like me, you can’t wait to get back to gardening, or if you want an early crop of vegetables, then there are a number of vegetable seeds which can be sown in February.

Some of these can be sown straight in the ground, such as Broad Beans, Cabbage, Cauliflower, Calabrese, Brussel Sprouts, Carrots, Leeks, Radish, Beetroot and Lettuce. Some need gentle heat – Greenhouse Tomatoes, Sweet Peppers (Capsicums) Aubergine, Cucumber and sprouting seeds among them.

When you are buying your seeds to sow at this time of year(Or any time, come to that) look carefully at the variety and make sure that it is suited to the purpose. For example, there is no use sowing an Autumn Cauliflower at this time of year, it simply won’t germinate.

The seeds which need heat can be germinated on the kitchen window sill if you want. Just make sure you are going to be able to plant them out before they get too ‘leggy’. All plants grow towards the light and if you sow seeds indoors, they will reach for the sky. If they are left indoors for too long, they will get tall and weak – this is called ‘leggy’.

I sow most of my vegetables (except root vegetables) in pots in my greenhouse. This is because I live in open country and know I have a number of pests in my garden which would love me to sow them a ready meal. It also means I can check that cauliflowers are not ‘blind’ before planting them out.

If you are germinating your seeds on a window sill, even if it is warm during the day, the night temperature will drop at this time of year. To ensure good germination and growth, the best thing to do is to use an electric propogator. Propogators are basically plastic boxes with electric heaters in the base. T & M sell a propogator especially designed to go on your windowsill. It has a 15 watt element, so is quite inexpensive to run and has 7 seperate mini trays with lids, so you can raise more than one types of seed in it.

Electric Propogatoes are very useful in a cold greenhouse at this time of year, both for seed germination and for raising cuttings. A propogators will ensure the soil stays at an even temperature which promotes growth. Alternately, Thompson and Morgan sell a heated propgation mat which you lay oin your staging. It has a thermostat sensor so will never get to hot, or cold and is inexpensive to run.

If want to raise very early crops inside your cold greenhouse, you may want to consider heating it for the three months from January to March. You should begin by double lining your greenhouse walls with pplastic, to give better insulation. If you have a large greenhouse, you may want to do this with part of it, to save heating bills. THen you put a heater in. YOu can use any type of heater you like, although gas heaters are not recommended because they are ubnsafe and also because they give off a great deal of water vapour. Thompson and Morgan sell an Electric Fan Heaterwhich is 1.2KW. This is particularly useful since you can use it in summer to keep the air circulating in your greenhouse and keep it cool. It also has a ‘frost watch’ setting so that it only works during the winter to keep your greenhouse frost free. This is useful if you are extending the season during late autumn and early winter.

Parsnips can be quite tricky to germinate. They will only germinate from fresh seed – no good trying to sow last years excess seed. They also need heat and damp. You can germinate them at this time of year by putting them on damp blotting paper (or kitchen roll). Put them in a plastic bag and then put them in the airing cupboard. Don’t forget them, though – they will go mouldy. When they have germinated, sow them normally.

It’s no good sowing any seed into ground that is frozen. This year has been unreasonably cold and at the moment, my ground is frozen solid However, you can expect a thaw anytime soon and when it comes – go for it. If you are concerned, sow half your seed and keep half back for a later sowing, that way should you have trouble with germination, you can always try again.

Sowing under cover will also help your germination. When you have sown your seed, cover the ground with horticultural fleece. This will help keep the warmth in, keep the predators (such as birds) off and allow the rain through.

Perennials, Bi-Annuals and Annuals.

Like most things, gardening has its own language and once you know that language, you can better understand how to garden well. A knowledge of Latin is useful, since many of the plant names have their origins in Latin. Even new varieties are using Latin in their names. However, this is not necessary since you don’t really need to know the meaning of the names to decide whether they are suitable for your garden and whether you like them. Some words, however are peculiar to gardening aand you need to know what they mean. Perennials, Bi=annuals and Annuals are three such words. Bi-Annuals are also often called Biennials.

Perennials are simply plants which will grow year after year. They generally refer to ornamental plants. When it come to flowers, there are perennials which die down to the ground every winter and shoot from the ground again in spring. These are known as ‘herbacious perennials’. You can cut these down as soon as they die back, if you wish. This makes your garden look tidier. Hoever, some seed heads (such as Poppies) look very attractive in winter when the frost settles on them. and some will feed birds. So you need to think about what you want to cut down and what you want to keep. A few years back, the general advice was to cut them all back since they can harbour pests and diseases. This is true. They can harbour pests and diseases and if the plant looks unwell, cut the dead foliage off. However, we now know that not all bugs are harmful so some  hiding places are good for your garden. I generally leave dead foliage for the worst of the winter. It protects young shots from frost and snow, then I cut it back when the worst of the winter is over.

Some of the most useful of the perennials are those which are either green over winter or even flower. I have had Polyanthus flowering all winter, even in the snow. It lifts my heart to see them. Pansies have also been bred to flower during the winter and these also provide colour when we most need it. Some plants naturally flower in the winter, such as Hellebore. You will find that generally, plants which flower in winter have very little or no scent as they are not trying to attract pollinating insects by scent.

Bi-annuals are plants which only flower in their second year and then die. However, some plants which we know as bi-annuals are really short-lived perennials and will flower a second, third and even a fourth time if we treat then right. Antirhinums are one of these plants, as are sweet william. After they have finished flowering, cut them back to three or four inches. They will flower then the following year. The problem is that they will become poorer in flower quality and will also become very woody, eventually  becoming unatractive plants. Some plants such as foxgloves have been bred so that they are true perennials rather than bi-annuals, although the original wild foxglove is, of course, still a bi-annual. Although bi-annuals , traditionally, grow the first year and flower the second, if you sow them early enough, you can persuade them to flower in their first year (and then they die).

Annuals are plants which grow, flower  and die all in one year. This group of plants include some of the most showy of our garden flowers, those plants we call ‘bedding plants’ and plants we call Half-hardy. This means that they will not live through frosts, so we need to sow the seed in a frost free place and wait until the frosts are over before planting them out. Some of the annuals (known as hardy annuals) can be sown where they are going to flower. Indeed, some plants need to be sown where they flower. These include many of the Poppies. This is because they do not like their roots being disturbed.

As you can see, different types of plants need different treatment, so you need to know what type of plants you are dealing with and treat them acordingly. That way you will get the best results from your seeds and plants.

Soil – And How To Treat It

The soil in your garden is the basic raw material upon which all plants depend. It should never be dismissed as merely a collection of mineral particles used to anchor the roots of your plants or, worse still as “dirt”.

The main constituent of  soil consists of rock partocles broken down by erosion to produce the different types of soil. However much of  its make up is organic matter, animal and vegetable remains in  various stages of decomposition along with air and water. This really is all you need to support  plant and animal life.The ideal soil has a crumbly structure full of organic matter. It drains well enough to prevent it becoming waterlogged in heavy rain and is capable of providing the nutrients needed by plants to grow healthily.

There are five main soil types: peat, chalk, silt, sand and clay. Generally, the rock upon which your soil is sitting dictates what kind of soil your have. Of course, there are many variation on the themes – such as sandy loam. This means that whilst a high proportion of your soil is sand, a large proportion is also silt.

When seen together the five different types of soil look very different. Most of us do not have purely one type of soil. However, here are a few pointers to soil types and how to improve them.

Clay is a heavy cold soil which feels sticky when moist and hard and compacted when dry. Because it is made up minute particles, it drains very poorly. However with some work, over time, it can be turned into a very workable, fertile soil. First, dig clay soils in the autumn when it is moist but not too wet. When digging in autumn, leave the top rough and uneven to expose the maximum area to the elements over winter so that freezing and thawing will work their magic. When digging incorporate plenty of organic matter to improve fertility. In addition, if your soil is very heavy, add course grit into the mix, this will help drainage. Raising the area of soil in which you  are goung to grow will help drainage.

Sand is a very light soil which tends to drain easily. It can therefore be cultivated when other soils are still water logged. However, because it drains so easily, nutrients are washed away so you need to add organic matter and fertilizer to the soil to improve fertility.

Silt soil has the same sort of  drainage problems as clay soil and the way you treat it is very similar, although you should not need the grit. However, adding plenty of well rotted compost and manure will help no end.

Chalk soil has two big disadvantages. Firstly, it tends to be very thin, dry and hungry. You need to add plant nutrients in the form of organic matter and fertilizers. Like sand, chalk soil drains very easily and the nutrients drain away with the water. The second disadvantage is that it is very alkaline and so unsuitable to many plants. However there are plants which require alkaline soils, so if you do have chalky soil, work with it and look carefully at plant requirements before trying to grow them.  Chalk soils  need to be covered  as much as possible, so use green manure crops during times when you are not growing other crops and mulch between plants where ever possible.

Peat is the easiest type of soil to grow plants in. If you are lucky enough to have it, you will know that it is very fertile. You can grow plants intensely. However, peat soils do tend to be acid and will therefore need generous applications of lime to keep the balance. It also tends to dry out in summer and if allowed to dry completely  it will shrink and be difficult to wet again.  The nature of peat soils mean that they are high in organic matter but probably low in nutrients so although it is not necessary to add organic matter , fertilizers may be needed.