Tips for profitable primrose production.

From around July onwards Growers prepare to take primrose plug plants and grow them on for sale in the winter. They are seen as a cheap and simple “cold” crop to grow. However, every year they manage to cause a fair few problems. Solufeed MD and industry expert Dick Holden shares some tips on how to grow the plants better.


Tip 1. Keep them cool.

Primroses don’t like it much above 15oC. Use shading or frequent light watering to keep them cool or they will suffer with temperature stress.

Tip 2. Don’t feed too much too soon.

Or they won’t develop the roots to scavenge for fertilizer. With plenty of compost base fertilizer they wont need any liquid feed for at least two weeks, and then bring it in slowly, starting at half rate (0.5 g/litre in the final feed) initially and increasing as the plant and its root system grow in size.

Tip 3. Transpiration prevents calcium deficiency: maintain air circulation.

Calcium deficiency shows as a yellowing to the margins of the oldest leaves. The yellowing eventually turns to dead tissue. The answer is not necessarily as simple as applying more calcium. Chances are that is it more to do with uptake of calcium than it is to do with the quantity of calcium that is available. Calcium is take up into the plants along with the water. Water is taken up in response to transpiration. So as the plant transpires water vapour through the leaves so more water is drawn up through the roots to replace it. And with it comes calcium. If the plant is not transpiring then it won’t be obtaining any calcium even if the roots are awash with it. So open the vents and maintain circulation as a priority to ward off calcium problems.

Tip 4. Beware of yellowing.

The leaves are as important as the flowers when you come to market the crop. Yellow or pale leaves are not acceptable. The usual cause is iron deficiency which shows up as a yellowing of the new growth.  However, like calcium deficiency, this is not necessarily as simple as shoving on more iron. The question is: why are the plants deficient? Often it is associated with another problem such as waterlogging which has stopped the roots working well.

Tip 5. Don’t run out of feed.

Sometimes growers stop feeding because they think the crop is close to market, so why waste the money? Or they feel that in the depths of a cold winter the plant cant use the feed. This can be a false economy because just when the plants need to look their best, the feed is withdrawn and in the event of any delay in marketing they can start to look deficient.

Tip 6. Feed with every watering.

If you don’t, and you decide to feed (for example) every other watering, then if you forget or miss a feed for any reason you will go for a long period with no feed. That will lead to problems. So feed with every watering, but just be prepared to cut back the amount you use if the crop gets too big.

Tip 7. Watch your conductivity.

Electrical Conductivity (EC) is a measure of the saltiness of the feed. Salts come from the background irrigation water + the added fertilizer salts (and any other additives such as mineral acid to control pH).  Excess salts can damage the root systems.  Keep the EC of the final irrigation water reaching the plant at no more than about 1.5 mS/cm (less if Controlled Release Fertilizer is used in the compost).

Tip 8. Watch your pH.

Your final irrigation water should have a target pH of around 6.5 i.e. just on the acid side of neutral. High pH often leads to poor utilization of fertilizer, deficiency diseases and susceptibility to other diseases. Low pH is less common but similarly debilitating. Normally high pH is managed by the use of mineral acids (e.g. nitric acid) going through “no-touch” automatic dosing systems. For growers without this equipment then AgroAcid offers a non-hazardous alternative, or there are acidic fertilizers that can help to some extent.

Tip 9. Full chelated trace elements are best.

Growers who mix their own feeds often use chelated iron (Fe EDTA), but then use sulphates for the other trace elements such as copper, manganese and zinc. If you put chelated iron in a stock tank with a metal sulphate such as copper sulphate, the chelate will move from the iron to chelate the copper in the tank. The iron is then free to react with phosphorus in the tank and is lost. For this reason always use fully chelated balanced trace element feeds such as Solufeed TEC, or use a fertilizer which contains all chelated trace elements in the correct balance such as Solufeed Primrose & Pansy Special.

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Tip 10. Solufeed products to consider.

Primrose & Pansy Special: A balanced soluble NPK feed with magnesium and 6 essential trace elements with the iron as the extra-available DTPA chelate.

Solufeed TEC:  for those growers who mix their own NPK but want a single product to provide the correct blend of fully chelated trace elements.

AgroAcid: A non-hazardous acid for pH adjustment.

Solufeed Fleury: A naturally acidic, non hazardous NPK fertilizer to help combat high pH water.

Natural Green: Foliar calcium from natural sources (39% calcium) to correct/prevent calcium deficiency.

Solufeed Rapid: Fast acting liquid iron chelate to correct iron deficiency.