Frosts

Late Frosts

Sadly a heavy frost struck our gardens on October 4 th.I hate these late frosts as they do so much damage to the emerging leaves .This was a particulary nasty frost as the air was very dry. The previous evening was very cold but windy so I didn’t put any frost cloths out to protect the frost sensitive plants. So I was badly caught out .It really annoyed me as I had been diligent all winter faithfully covering the tender plants.And it only takes one frost to do a heck of a lot of damage. It made me wonder why can’t our weather presenters forecast frosts for us, particulary when they are out of season. Although winter has passed it is not unusual for us to get frosts right up to the end of October, but it is rare for them to be so heavy.

There is evidence of frost damage in all of the gardens I have visited since that late frost. New Hosta leaves have become transparent with the damage, Hydrangeas leaves have blackened, new foliage on Camellias has wilted and many natives have blackened new leaves. And these are the normally frost tolerant species.Luckily my potatoes had their leaves covered over with pea straw but I pity all the poor summer veggies that have been planted out over the past few weeks.

I have felt for many years cross with nurseries and Garden centres who offer for sale far too early in the season tender plants such as Tomatoes, Zucchinnis, Cucumbers,Pumpkins and the like. Traditionally Labour weekend heralds the earliest time that these plants should be planted out in the open. And with good reason.It is only then that the soil temperature is reliably suitable for these plants. Even if you have a frost free garden tender plants put out too early will be slow to put on any growth. Experiments have shown that tender plants planted at the correct time will in fact grow more quickly and overtake plants that were planted out earlier in the season. Also plants that have had a check, eg frost damage or being beaten up with the wind are more prone to disease attack. When outdoor Tomatoes were such an important part of Otaki’s market garden scene I used to watch for the first sign of plantings before undertaking my own. And it was never before Labour weekend.

I was horrified to see for sale in early August punnets of dwarf bean plants. Such healthy strong seedlings but all doomed to die. I questioned the buyer who naively replied that the nursery was offering them for sale so why not buy them.If only the nursery was forward enough thinking to realize what a disservice they are doing to their industry. Yes the customers would buy them and within two weeks when the poor plants would have died out in the cold there would be more gaps to fill so more plants would be purchased .But these bean plants would not have been purchased by seasoned gardeners as we all know beans don’t grow in our area until November. Instead keen new gardeners would have snapped up the beans and sadly questioned their ability to successfully grow plants when their beans failed. Such failures are the catalyst for many would be gardeners to give up gardening.

Although late frosts blacken leaves and generally cause shrubs to look ill the damage caused will rarely be fatal. The same can not be said for tender annuals. They will melt away into a blackened mush. With the shrubs refrain from removing the damaged leaves until at least the beginning of November. The damaged leaves will protect any emerging leaves and shoots from subsequent frosts. Once the new shoots have grown it is easier to see where to cut back to. On shrubs that are prone to disease attack, eg roses and grapes remove the damaged foliage as soon as new shoots have formed. This discourages disease spores from lurking and multiplying within the shelter of the damaged leaves.