How to Revive a Dying Rosemary Plant


How to revive a dying rosemary plant

Rosemary are low maintenance, hardy perennial plant that lives up to 15 years with the right care.

Rosemary is native to Southern European countries that boarder the Mediterranean sea and are therefore specifically adapted to the conditions of the Mediterranean environment.

In order to revive rosemary you have to emulate some of the growing conditions of the Mediterranean with a strong emphasis on well draining soils, full sun and infrequent watering.

If your rosemary looks unwell there are several ways to help it revive but first you have to identify what is causing the problems…

Identify Why the Rosemary needs Reviving

The most common reasons rosemary needs reviving are:

  • Root rot due to persistent moisture around the roots. Rosemary is sensitive to over watering which can cause the plant to droop and the leaves to turn brown or yellow.
  • Rosemary in pots can suffer from poor growth, yellow or brown foliage due to being pot bound or planted in a pot that does not have drainage holes in the base.
  • Rosemary that is not growing (due to lack of sun, lack of regular good pruning, or the roots are pot bound).
  • Rosemary that is frost damaged or not growing back after Winter.
  • Rosemary that is turning yellow with few flowers due to over watering or too much nitrogen because of additional fertilizer or nutrient rich soils.

Keep reading to learn how to solve these problems and revive the rosemary plant so that it recovers with healthy green foliage, better aroma, stronger flavour and flowers the following year…

Rosemary with Root Rot

  • Symptoms. Rosemary with root rot tends to look somewhat wilted or drooping with foliage that turns brown, yellow or black or has a dried and brittle appearance.
  • Causes. Over watering, high rainfall, high humidity and slow draining soils, contribute to the conditions for root rot and fungal disease.

Root rot and fungal diseases that attack the roots, are the most common reasons rosemary plants die.

Rosemary originates from the Mediterranean region of Europe where it lives in sandy or stony well draining soils often by the coast or on hill sides.

Their natural climate is one of infrequent rainfall with low humidity, blazing sunshine with higher temperatures and they enjoy a good breeze which helps to reduce moisture around the foliage.

When rosemary becomes established (after a couple of years) it is regarded as a drought resistant plant that thrives on neglect.

The problems with growing rosemary are usually because of too much care and attention from gardeners.

Rosemary can thrive with being watered once every two weeks in hot weather (as long as the pot is over 16 inches) and does not require additional water in Winter.

Root rot can occur at anytime due to too much moisture around the roots but it is particularly prevalent in Winter when there is higher rainfall and lower levels of evaporation.

Rosemary roots

How to Revive Rosemary With Root Rot

  • If your rosemary is showing symptoms of root rot then it is important to scale back the watering immediately. If the rosemary is in a pot then shelter it from rainfall if possible to allow the soil a chance to dry out.
  • Remove any moisture retentive matter from around the base of the rosemary that may contribute to moisture around the roots, such as dead leaves, compost or any organic mulch.
  • If the brown foliage and stems are extensive and progressively getting worse then remove the rosemary from the pot or lift it out the ground (if possible) and inspect the roots. Snip away any dark or slimy roots that you can seen and snip away any brown foliage or stems back to healthy growth. Wipe the pruners with a cloth and disinfectant after each cut to prevent spreading fungus.
  • Replant the rosemary, ideally in a new pot as pots have more favourable drainage with a potting mix of at least 20% sand or grit and 80% potting soil or compost to replicate the soil of rosemarys native environment. Always locate rosemary in full sun.

By replanting the rosemary in new soil, reducing the watering and sheltering the plant from rainfall where possible the rosemary has the best chance of reviving.

If your garden is boggy, has clay soil or has particularly moisture retentive soil due to amendments of organic matter then planting rosemary in pots is by far the best option as it is likely to die of root rot if it is left in slow draining garden soil.

Sandy soil for rosemary

With pots and containers, you have far greater control of the soil profile and it is much easier to add horticultural sand or grit to improve the drainage and aeration of the soil to help the roots dry out between bouts of watering and stay healthy.

Full sun is imperative for growing rosemary as it increases the health of the plant which improves its resilience to root rot and fungal diseases which can help it recover.

Fungal disease tends to attack unhealthy plants so by recreating the conditions in which rosemary thrive you can ensure the plant is better able to fight disease and hopefully recover.

If the root rot is extensive (most of the foliage or stems are turning brown or yellow and the plant is drooping) then the rosemary may not recover and it may be worth replacing the rosemary and treating the soil with an organic fungicide so that any fungus does not transfer onto new plants.

Alternatively you can attempt to propagate some healthy cuttings from the plant as rosemary has a reasonably high success rate with propagation and you can start several plants for free.

(To learn more read my article why is my rosemary turning brown?)

Revive Rosemary in Pots and Containers

Rosemary grows exceptionally well in pots and containers (if the conditions are suitable) because of the favourable drainage of pots compared to garden soil.

However rosemary can suffer in pots if:

  • The pot is too small which causes pot bound roots slower growth and the foliage may turn yellow.
  • The rosemary can suffer stress due to damp soil if the pot does not have drainage holes in the base.

How to Revive Rosemary in Pots

  • Plant the rosemary (or transplant) into a large pot of around 16 inches if the roots are pot bound. Use a soil mix of compost or potting soil and sand to ensure the optimal drainage conditions.
  • Ensure the pot has drainage holes at the base and do not use a drip tray under the pot as this can keep the soil damp.

Always plant the rosemary in a reasonably large (16 inches across of more) pot or container. A larger pot allows the roots to establish properly so it can access the water and nutrients it requires.

A larger pot has the capacity for more soil which can help insulate the rosemary roots in Winter.

With a larger pot and new soil the a rosemary plant that has pot bound roots should recover over a few weeks with green foliage, stronger aroma and flavour.

A common mistake with growing rosemary is to plant it in a decorative pot or use a drip tray so the excess water does not escape after watering. This mimics the affects of over watering and increases the risk of root rot.

Always plant rosemary in a pot with drainage holes in the base and avoid using a drip tray. Using feet for the pot to elevate it off the ground can improve the drainage and also allow you to catch the water in a tray if necessary (such as if you are growing rosemary indoors and do not want water to trickle out the pot).

This will allow excess water to escape after watering and allow the soil around the roots to dry out so that they can stay healthy.

(Read my article how to water rosemary for how to establish the optimal watering schedule for your garden).

Revive Rosemary That is Not Growing

  • Symptoms. Slow growth with spindly, perhaps woody branches and few blooms
  • Causes. Rosemary not in full sun, plant may be pot bound and not pruned regularly.

Rosemary grows best in full sun and does not grow very well in the shade.

The leaves are at their most aromatic and flavourful in the hottest, sunniest years as the amount of sunlight directly correlates with the essential oils in the rosemary leaves that give it its distinctive taste and aroma.

Rosemary rarely suffers from problems associated with a deficit of nutrients as it has adapted to grow in low to medium nutrient soils that have a relatively high sand or grit content.

However they may suffer if the pot is too small as the roots have limited access to nutrients which can slow down the growth of the rosemary.

Rosemary leaves and stems can be pruned at anytime during the growing season to for cooking, however rosemary does respond to a hard prune once per year in order to stimulate new growth and to slow down the formation of the woody base.

How to Revive Rosemary that is not Growing

Always plant the rosemary in full sun for best results otherwise it may not grow in the shade and not live for very long. Transplant the rosemary into full sun or (more conveniently) if its potted move the pot into the sun and the rosemary should revive and start growing again if it is in the growing season.

Rosemary thrives in poor soils that are sandy so it is rarely affected by a lack of nutrients, however a pot bound plant can become root bound or exhaust the potting soil of nutrients if it has been in the same pot for a long time.

The solution is to replant the rosemary in a new pot that is significantly larger then the previous pot (around 16 inches across). This will give the rosemary roots more room to establish and uptake nutrients so it can start growing.

A weak fertilizer in the Spring can also help if the rosemary has been deprived of nutrients in a smaller pot.

A half strength fertilizer is all that is required. Too much fertilizer and it can burn the roots or stimulate new sappy growth and leaves with less flavour and fragrance that is also more susceptible to disease.

Rosemary can be pruned for its leaves for culinary purposes at any time during Spring or Summer and up until early Fall.

However it is a good to give the rosemary a good prune to stimulate new growth. The key with pruning is to not cut into the woody base of the rosemary as the older wood does not grow new leaves.

Here’s a really good YouTube video which explains how to prune rosemary for good growth with plentiful leaves:

Rosemary With Damage After Winter

  • Symptoms. Brown foliage that looks damaged (particularly the tender new leaves).
  • Causes. Rosemary is not particularly cold hardy. The roots and leaves are vulnerable to frost damage and root rot during Winter.

Rosemary is a plant that originates from the hot climate of the Mediterranean where the Winters are relatively mild and do not go below freezing.

Therefore it is not a cold hardy plant (hardy to USDA zone 7) and is often damaged by frost, snow and ice, with mature plants faring better in cold weather and younger plants more susceptible to damage.

If your garden is in a cold climate that regularly experiences hard frosts during Winter then I recommend that you grow rosemary in a pot so you can take it indoors (and place in a sunny window in your house or garage or heated green house) over Winter.

Of course you can also preemptively protect the rosemary planted in the garden with fleece or a cloche before a frosty night which can help to prevent damage.

Rosemary rarely requires any fertilizer due to its preference for low to medium nutrient soils, however if you do have cause to fertilize the rosemary then make sure it is in the early Spring as fertilizing too late in the growing season can stimulate new growth which is more vulnerable to frost damage.

Do not prune rosemary too late in the Fall as pruning can stimulate new growth which ideally requires time to mature so it is more resilient during cold temperatures in the Winter months.

How to Revive Rosemary After Winter

  • Snip off any frost damaged stems or leaves from the rosemary in the Spring after the last frost.
  • Improve the drainage of your soil by amending with sand or grit to prevent damp soils which risk root rot.
  • Plant rosemary in a large pot so the soil can insulate the roots.

It is important to plant rosemary in a relavively large pot if you live in a climate with cold Winters.

The woody part of the rosemary is least vulnerable to cold weather and is usually relatively unaffected by light frosts. The newer, tender growth and is far more vulnerable to frost damage with the roots being the most at risk from freezing temperatures.

To protect the roots transplant your rosemary to a larger pot as this will have more capacity for soil which will help protect the roots from the cold. If the rosemary is planted in the ground it will usually be well protected from frost.

Do not cut back frost damaged parts of the rosemary during Winter whilst there is still a threat of frost in the early Spring as this leaves the rosemary more vulnerable to frost damage from the point at which it has been cut.

When the weather has warmed up in the Spring, is the best time to cut back the frost damage on the rosemary, cutting back to the healthy part of the stem. This will stimulate new growth and help to revive the rosemary.

If the rosemary is brittle and brown after Winter then it may have suffered from root rot over Winter and it is likely dead (unless there is some healthy growth from which to take cuttings for propagation).

Rosemary is most vulnerable to fungal disease during Winter due to cold damp soils. This highlights the importance of amending soils before planting with sand or grit to improve the drainage.

For potted rosemary it is a good idea to transfer the plant to a new pot with potting soil that has around 20% sand or grit and 80% compost.

If the rosemary is in the ground then I recommend using a fork to make space in the soil around the rosemary (whilst carefully avoiding the roots) and sprinkling horticultural sand in the soil to improve the drainage without disturbing the plant too much.

Proactive action is always best when it comes to caring for rosemary during Winter but by pruning back the frost damaged growth you can revive the rosemary for the growing season.

Rosemary With Yellow leaves and Few Flowers

  • Symptoms. Rosemary has foliage that is turning yellow with few flowers and a weaker aroma and less culinary taste.
  • Causes. Often caused by an excess of nitrogen due to nutrient rich soils or because of too much fertilizer.
Yellow rosemary leaves
Leaves of rosemary turning yellow

Rosemary thrives in low to medium nutrient soils that are often sandy or stony because this is often the soil conditions in its native Mediterranean range.

When rosemary is planted by gardeners, the soil is might be amended by manure of nutrient rich soil that contains high amounts of nitrogen of the use of fertilizer.

This is to the contrary of the rosemary preferred conditions of sandy soils that do not retain much nutrients.

Too much nitrogen is not good for rosemary as it can burn the roots, cause the foliage to turn yellow and decrease the aroma and culinary value of the leaves.

Also excess nitrogen will stimulate lots of foliage growth (but without much taste) at the expense of flowers.

Rosemary smells the strongest and tastes its best when in relatively poor soils with full sun and infrequent watering.

How To Revive Rosemary With Yellow leaves and Few flowers

The way to revive rosemary with yellow leaves and a weak aroma is to try and mimic the soil conditions of the Mediterranean and avoid the use of fertilizer in most cases.

Rosemary is a hardy plant that thrives on neglect so it rarely requires additional fertilizer. Yellow leaves are often a sign of too much nitrogen rather then a deficit.

  • Stop using fertilizer if you are consistently doing so. Too much fertilizer is harmful so avoid using fertilizer and the rosemary leaves will begin to green up over time with an increase in the strength of the aroma over the next few weeks and months.
  • If it is at all possible, it is a good idea to try and amend the soil so it contains more sand or grit as they to do not contribute much in terms of nutrients to the soil and they help to improve drainage a porous structure which rosemary plants prefer.

Amending the soil is much easier if the rosemary is in a pot or container as you can just add sand when re-potting or transplant the rosemary to a new pot with a sandy soil mix of around 20% sand or grit and 80% potting soil or compost.

However if the rosemary is in the ground and it is a large established plant the best course of action is again to use a fork to help aerate the soil around the roots and distribute sand around the base of the plant which improves the soils structure and balances high nutrient soils so that the concentration of nitrogen is not as strong.

Over the course of a few month this should help the rosemary to recover and the foliage can turn from yellow to a healthy green although it may be a year before the rosemary flowers properly again.

(To learn more about the solutions, read my article why is my rosemary turning yellow?)

Key Takeaways:

  • The reason why rosemary needs reviving is usually because of root rot, yellow leaves, a lack of growth with poor aroma and flavour or damage after Winter.
  • To revive rosemary with root rot you need to improve the soil drainage, cut back on watering frequency and space the rosemary so that it has more of a breeze around the foliage. When amending the soil inspect the roots of the rosemary and snip off diseased, slimy roots.
  • Plant or transfer the rosemary to a more generous pot or container so that there is enough soil to insulate the roots and enough nutrients for the rosemary to grow properly.
  • Frost damaged growth on rosemary should be cut back after Winter when the weather has warmed up and this will stimulate new growth. Ensure the soil is well draining as damp soils in Winter are often the cause of root rot or promote fungal disease.
  • Rosemary thrives in poor to medium nutrient soils. Rosemary can turn yellow and display fewer flowers due to over watering, high nutrient soil or the use of fertilizer. Rosemary often does not require any fertiliser and should be planted in soil that has been amended with sand or grit so that the nitrogen content of the soil is balanced. Rosemary should recover by the following year if you avoid fertilizer and amend the soil so that it emulates the soil of its native Mediterranean home range.

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